Le clans des mouettes

ainsi est la force.
AccueilAccueil  FAQFAQ  RechercherRechercher  S'enregistrerS'enregistrer  MembresMembres  GroupesGroupes  Connexion  

Partagez | 


Aller en bas 
yanis la chouette

Nombre de messages : 9682
Localisation : http://yanis.tignard.free.fr/
Date d'inscription : 09/11/2005



Marie Pasteur, née Laurent (15 January 1826 in Clermont-Ferrand, France – 28 September 1910 in Paris), was the scientific assistant and co-worker of her spouse, the famous French chemist and bacteriologist Louis Pasteur.

Louis Pasteur (/ˈluːi pæˈstɜːr/, French: [lwi pastœʁ]; December 27, 1822 – September 28, 1895) was a French biologist, microbiologist and chemist renowned for his discoveries of the principles of vaccination, microbial fermentation and pasteurization. He is remembered for his remarkable breakthroughs in the causes and prevention of diseases, and his discoveries have saved many lives ever since. He reduced mortality from puerperal fever, and created the first vaccines for rabies and anthrax. His medical discoveries provided direct support for the germ theory of disease and its application in clinical medicine. He is best known to the general public for his invention of the technique of treating milk and wine to stop bacterial contamination, a process now called pasteurization. He is regarded as one of the three main founders of bacteriology, together with Ferdinand Cohn and Robert Koch, and is popularly known as the "father of microbiology".[4][5][6]

Pasteur was responsible for disproving the doctrine of spontaneous generation. He performed experiments that showed that without contamination, microorganisms could not develop. Under the auspices of the French Academy of Sciences, he demonstrated that in sterilized and sealed flasks nothing ever developed, and in sterilized but open flasks microorganisms could grow.[7] Although Pasteur was not the first to propose the germ theory, his experiments indicated its correctness and convinced most of Europe that it was true. Today, he is often regarded as one of the fathers of germ theory.[8] Pasteur made significant discoveries in chemistry, most notably on the molecular basis for the asymmetry of certain crystals and racemization. Early in his career, his investigation of tartaric acid resulted in the first resolution of what is now called optical isomers. His work led the way to the current understanding of a fundamental principle in the structure of organic compounds.

He was the director of the Pasteur Institute, established in 1887, until his death, and his body was interred in a vault beneath the institute. Although Pasteur made groundbreaking experiments, his reputation became associated with various controversies. Historical reassessment of his notebook revealed that he practiced deception to overcome his rivals.[9][10]

Molecular asymmetry
Pasteur separated the left and right crystal shapes from each other to form two piles of crystals: in solution one form rotated light to the left, the other to the right, while an equal mixture of the two forms canceled each other's effect, and does not rotate the polarized light.

In Pasteur's early work as a chemist, beginning at the École Normale Supérieure, and continuing at Strasbourg and Lille, he examined the chemical, optical and crystallographic properties of a group of compounds known as tartrates.[37]

He resolved a problem concerning the nature of tartaric acid in 1848.[38][39][40][41] A solution of this compound derived from living things rotated the plane of polarization of light passing through it.[37] The problem was that tartaric acid derived by chemical synthesis had no such effect, even though its chemical reactions were identical and its elemental composition was the same.[42]

Pasteur noticed that crystals of tartrates had small faces. Then he observed that, in racemic mixtures of tartrates, half of the crystals were right-handed and half were left-handed. In solution, the right-handed compound was dextrorotatory, and the left-handed one was levorotatory.[37] Pasteur determined that optical activity related to the shape of the crystals, and that an asymmetric internal arrangement of the molecules of the compound was responsible for twisting the light.[31] The (2R,3R)- and (2S,3S)- tartrates were isometric, non-superposable mirror images of each other. This was the first time anyone had demonstrated molecular chirality, and also the first explanation of isomerism.[37]

Some historians consider Pasteur's work in this area to be his "most profound and most original contributions to science", and his "greatest scientific discovery."[37]
Fermentation and germ theory of diseases

Pasteur was motivated to investigate fermentation while working at Lille. In 1856 a local wine manufacturer, M. Bigot, whose son was one of Pasteur's students, sought for his advice on the problems of making beetroot alcohol and souring.[43][44]

According to his son-in-law, René Vallery-Radot, in August 1857 Pasteur sent a paper about lactic acid fermentation to the Société des Sciences de Lille, but the paper was read three months later.[45] A memoire was subsequently published on November 30, 1857.[46] In the memoir, he developed his ideas stating that: "I intend to establish that, just as there is an alcoholic ferment, the yeast of beer, which is found everywhere that sugar is decomposed into alcohol and carbonic acid, so also there is a particular ferment, a lactic yeast, always present when sugar becomes lactic acid."[47] Pasteur also wrote about alcoholic fermentation.[48] It was published in full form in 1858.[49][50] Jöns Jacob Berzelius and Justus von Liebig had proposed the theory that fermentation was caused by decomposition. Pasteur demonstrated that this theory was incorrect, and that yeast was responsible for fermentation to produce alcohol from sugar.[51] He also demonstrated that, when a different microorganism contaminated the wine, lactic acid was produced, making the wine sour.[44] In 1861, Pasteur observed that less sugar fermented per part of yeast when the yeast was exposed to air.[51] The lower rate of fermentation aerobically became known as the Pasteur effect.[52]
Pasteur experimenting in his laboratory.
Institut Pasteur de Lille

Pasteur's research also showed that the growth of micro-organisms was responsible for spoiling beverages, such as beer, wine and milk. With this established, he invented a process in which liquids such as milk were heated to a temperature between 60 and 100 °C.[53] This killed most bacteria and moulds already present within them. Pasteur and Claude Bernard completed tests on blood and urine on April 20, 1862.[54] Pasteur patented the process, to fight the "diseases" of wine, in 1865.[53] The method became known as pasteurization, and was soon applied to beer and milk.[55]

Beverage contamination led Pasteur to the idea that micro-organisms infecting animals and humans cause disease. He proposed preventing the entry of micro-organisms into the human body, leading Joseph Lister to develop antiseptic methods in surgery.[56]

In 1866, Pasteur published Etudes sur le Vin, about the diseases of wine, and he published Etudes sur la Bière in 1876, concerning the diseases of beer.[51]

In the early 19th century, Agostino Bassi had shown that muscardine was caused by a fungus that infected silkworms.[57] Since 1853, two diseases called pébrine and flacherie had been infecting great numbers of silkworms in southern France, and by 1865 they were causing huge losses to farmers. In 1865, Pasteur went to Alès and worked for five years until 1870.[58][59]

Silkworms with pébrine were covered in corpuscles. In the first three years, Pasteur thought that the corpuscles were a symptom of the disease. In 1870, he concluded that the corpuscles were the cause of pébrine (it is now known that the cause is a microsporidian).[57] Pasteur also showed that the disease was hereditary.[60] Pasteur developed a system to prevent pébrine: after the female moths laid their eggs, the moths were turned into a pulp. The pulp was examined with a microscope, and if corpuscles were observed, the eggs were destroyed.[61][60] Pasteur concluded that bacteria caused flacherie. The primary cause is currently thought to be viruses.[57] The spread of flacherie could be accidental or hereditary. Hygiene could be used to prevent accidental flacherie. Moths whose digestive cavities did not contain the microorganisms causing flacherie were used to lay eggs, preventing hereditary flacherie.[62]
Spontaneous generation
Bottle en col de cygne (swan-neck bottle) used by Pasteur
Louis Pasteur’s pasteurization experiment illustrates the fact that the spoilage of liquid was caused by particles in the air rather than the air itself. These experiments were important pieces of evidence supporting the germ theory of disease.

Following his fermentation experiments, Pasteur demonstrated that the skin of grapes was the natural source of yeasts, and that sterilized grapes and grape juice never fermented. He drew grape juice from under the skin with sterilized needles, and also covered grapes with sterilized cloth. Both experiments could not produce wine in sterilized containers.[44]

His findings and ideas were against the prevailing notion of spontaneous generation. He received a particularly stern criticism from Félix Archimède Pouchet, who was director of the Rouen Museum of Natural History. To settle the debate between the eminent scientists, the French Academy of Sciences offered the Alhumbert Prize carrying 2,500 francs to whoever could experimentally demonstrate for or against the doctrine.[63][64][65]

Pouchet stated that air everywhere could cause spontaneous generation of living organisms in liquids.[66] In the late 1850s, he performed experiments and claimed that they were evidence of spontaneous generation.[67][63] Francesco Redi and Lazzaro Spallanzani had provided some evidence against spontaneous generation in the 17th and 18th centuries, respectively. Spallanzani's experiments in 1765 suggested that air contaminated broths with bacteria. In the 1860s, Pasteur repeated Spallanzani's experiments, but Pouchet reported a different result using a different broth.[58]

Pasteur performed several experiments to disprove spontaneous generation. He placed boiled liquid in a flask and let hot air enter the flask. Then he closed the flask, and no organisms grew in it.[67] In another experiment, when he opened flasks containing boiled liquid, dust entered the flasks, causing organisms to grow in some of them. The number of flasks in which organisms grew was lower at higher altitudes, showing that air at high altitudes contained less dust and fewer organisms.[44][68] Pasteur also used swan neck flasks containing a fermentable liquid. Air was allowed to enter the flask via a long curving tube that made dust particles stick to it. Nothing grew in the broths unless the flasks were tilted, making the liquid touch the contaminated walls of the neck. This showed that the living organisms that grew in such broths came from outside, on dust, rather than spontaneously generating within the liquid or from the action of pure air.[44][69]

These were some of the most important experiments disproving the theory of spontaneous generation, for which Pasteur won the Alhumbert Prize in 1862.[67] He concluded that:[44][59]

   Never will the doctrine of spontaneous generation recover from the mortal blow of this simple experiment. There is no known circumstance in which it can be confirmed that microscopic beings came into the world without germs, without parents similar to themselves.

Immunology and vaccination
Chicken cholera

Pasteur's later work on diseases included work on chicken cholera. He received cultures from Jean Joseph Henri Toussaint, and cultivated them in chicken broth.[70] During this work, a culture of the responsible bacteria had spoiled and failed to induce the disease in some chickens he was infecting with the disease. Upon reusing these healthy chickens, Pasteur discovered he could not infect them, even with fresh bacteria; the weakened bacteria had caused the chickens to become immune to the disease, though they had caused only mild symptoms.[4][8]

In 1879, his assistant, Charles Chamberland (of French origin), had been instructed to inoculate the chickens after Pasteur went on holiday. Chamberland failed to do this and went on holiday himself. On his return, the month-old cultures made the chickens unwell, but instead of the infections being fatal, as they usually were, the chickens recovered completely. Chamberland assumed an error had been made, and wanted to discard the apparently faulty culture, but Pasteur stopped him.[71][72] He inoculated the chickens with virulent bacteria that killed other chickens, and they survived. Pasteur concluded that the animals were now immune to the disease.[73]

In December 1879, Pasteur used a weakened culture of the bacteria to inoculate chickens. The chickens survived, and when he inoculated them with a virulent strain, they were immune to it. In 1880, Pasteur presented his results to the French Academy of Sciences, saying that the bacteria were weakened by contact with oxygen.[70]

In the 1870s, he applied this immunization method to anthrax, which affected cattle, and aroused interest in combating other diseases. Pasteur cultivated bacteria from the blood of animals infected with anthrax. When he inoculated animals with the bacteria, anthrax occurred, proving that the bacteria was the cause of the disease.[74] Many cattle were dying of anthrax in "cursed fields".[59] Pasteur was told that sheep that died from anthrax were buried in the field. Pasteur thought that earthworms might have brought the bacteria to the surface. He found anthrax bacteria in earthworms' excrement, showing that he was correct.[59] He told the farmers not to bury dead animals in the fields.[75]
Louis Pasteur in his laboratory, painting by A. Edelfeldt in 1885

In 1880, Pasteur's rival Jean-Joseph-Henri Toussaint, a veterinary surgeon, used carbolic acid to kill anthrax bacilli and tested the vaccine on sheep. Pasteur thought that this type of killed vaccine should not work because he believed that attenuated bacteria used up nutrients that the bacteria needed to grow. He thought oxidizing bacteria made them less virulent.[76] In early 1881, Pasteur discovered that growing anthrax bacilli at about 42 °C made them unable to produce spores,[77] and he described this method in a speech to the French Academy of Sciences on February 28.[78] Later in 1881, veterinarian Hippolyte Rossignol proposed that the Société d'agriculture de Melun organize an experiment to test Pasteur's vaccine. Pasteur agreed, and the experiment, conducted at Pouilly-le-Fort on sheep, goats and cows, was successful. Pasteur did not directly disclose how he prepared the vaccines used at Pouilly-le-Fort.[79][77] His laboratory notebooks, now in the Bibliothèque Nationale in Paris, show that he actually used heat and potassium dichromate, similar to Toussaint's method.[80][42][81]

The notion of a weak form of a disease causing immunity to the virulent version was not new; this had been known for a long time for smallpox. Inoculation with smallpox (variolation) was known to result in a much less severe disease, and greatly reduced mortality, in comparison with the naturally acquired disease.[82] Edward Jenner had also studied vaccination using cowpox (Vaccinia) to give cross-immunity to smallpox in the late 1790s, and by the early 1800s vaccination had spread to most of Europe.[83]

The difference between smallpox vaccination and anthrax or chicken cholera vaccination was that the latter two disease organisms had been artificially weakened, so a naturally weak form of the disease organism did not need to be found.[80] This discovery revolutionized work in infectious diseases, and Pasteur gave these artificially weakened diseases the generic name of "vaccines", in honour of Jenner's discovery.[84]
Main article: Koch–Pasteur rivalry

In 1876, Robert Koch had shown that Bacillus anthracis caused anthrax.[85] In his papers published between 1878 and 1880, Pasteur only mentioned Koch's work in a footnote. Koch met Pasteur at the Seventh International Medical Congress in 1881. A few months later, Koch wrote that Pasteur had used impure cultures and made errors. In 1882, Pasteur replied to Koch in a speech, to which Koch responded aggressively.[8] Koch stated that Pasteur tested his vaccine on unsuitable animals and that Pasteur's research was not properly scientific.[44] In 1882, Koch wrote "On the Anthrax Inoculation", in which he refuted several of Pasteur's conclusions about anthrax and criticized Pasteur for keeping his methods secret, jumping to conclusions, and being imprecise. In 1883, Pasteur wrote that he used cultures prepared in a similar way to his successful fermentation experiments and that Koch misinterpreted statistics and ignored Pasteur's work on silkworms.[85]
Swine erysipelas

In 1882, Pasteur sent his assistant Louis Thuillier to southern France because of an epizootic of swine erysipelas.[86] Thuillier identified the bacillus that caused the disease in March 1883.[58] Pasteur and Thuillier increased the bacillus's virulence after passing it through pigeons. Then they passed the bacillus through rabbits, weakening it and obtaining a vaccine. Pasteur and Thuillier incorrectly described the bacterium as a figure-eight shape. Roux described the bacterium as stick-shaped in 1884.[87]

Pasteur produced the first vaccine for rabies by growing the virus in rabbits, and then weakening it by drying the affected nerve tissue.[59][88] The rabies vaccine was initially created by Emile Roux, a French doctor and a colleague of Pasteur, who had produced a killed vaccine using this method.[44] The vaccine had been tested in 50 dogs before its first human trial.[89][90] This vaccine was used on 9-year-old Joseph Meister, on July 6, 1885, after the boy was badly mauled by a rabid dog.[42][88] This was done at some personal risk for Pasteur, since he was not a licensed physician and could have faced prosecution for treating the boy.[6] After consulting with physicians, he decided to go ahead with the treatment.[91] Over 11 days, Meister received 13 inoculations, each inoculation using viruses that had been weakened for a shorter period of time.[92] Three months later he examined Meister and found that he was in good health.[91][93] Pasteur was hailed as a hero and the legal matter was not pursued.[6] Analysis of his laboratory notebooks shows that Pasteur had treated two people before his vaccination of Meister. One survived but may not actually have had rabies, and the other died of rabies.[92][94] Pasteur began treatment of Jean-Baptiste Jupille on October 20, 1885, and the treatment was successful.[92] Later in 1885, people, including four children from the United States, went to Pasteur's laboratory to be inoculated.[91] In 1886, he treated 350 people, of which only one developed rabies.[92] The treatment's success laid the foundations for the manufacture of many other vaccines. The first of the Pasteur Institutes was also built on the basis of this achievement.[42]

In The Story of San Michele, Axel Munthe writes of some risks Pasteur undertook in the rabies vaccine research:[95]

   Pasteur himself was absolutely fearless. Anxious to secure a sample of saliva straight from the jaws of a rabid dog, I once saw him with the glass tube held between his lips draw a few drops of the deadly saliva from the mouth of a rabid bull-dog, held on the table by two assistants, their hands protected by leather gloves.

Because of his study in germs, Pasteur encouraged doctors to sanitize their hands and equipment before surgery. Prior to this, few doctors or their assistants practiced these procedures.

A French national hero at age 55, in 1878 Pasteur discreetly told his family never to reveal his laboratory notebooks to anyone. His family obeyed, and all his documents were held and inherited in secrecy. Finally, in 1964 Pasteur's grandson and last surviving male descendant, Pasteur Valley-Radot, donated the papers to the French national library (Bibliothèque nationale de France). Yet the papers were restricted for historical studies until the death of Valley-Radot in 1971. The documents were given a catalogue number only in 1985.[96]

In 1995, the centennial of the death of Louis Pasteur, a historian of science Gerald L. Geison published an analysis of Pasteur's private notebooks in his The Private Science of Louis Pasteur, and declared that Pasteur had given several misleading accounts and played deceptions in his most important discoveries.[9][97] Max Perutz published a defense of Pasteur in The New York Review of Books.[98] Based on further examinations of Pasteur's documents, French immunologist Patrice Debré concluded in his book Louis Pasteur (1998) that in spite of his genius, Pasteur had some faults. A book review states that Debré "sometimes finds him unfair, combative, arrogant, unattractive in attitude, inflexible and even dogmatic".[99][100]

Scientists before Pasteur had studied fermentation. In the 1830s, Charles Cagniard-Latour, Friedrich Traugott Kützing and Theodor Schwann used microscopes to study yeasts and concluded that yeasts were living organisms. In 1839, Justus von Liebig, Friedrich Wöhler and Jöns Jacob Berzelius stated that yeast was not an organism and was produced when air acted on plant juice.[51]

In 1855, Antoine Béchamp, Professor of Chemistry at the University of Montpellier, conducted experiments with sucrose solutions and concluded that water was the factor for fermentation.[101] He changed his conclusion in 1858, stating that fermentation was directly related to the growth of moulds, which required air for growth. He regarded himself as the first to show the role of microorganisms in fermentation.[102][47]

Pasteur started his experiments in 1857 and published his findings in 1858 (April issue of Comptes Rendus Chimie, Béchamp's paper appeared in January issue). Béchamp noted that Pasteur did not bring any novel idea or experiments. On the other hand, Béchamp was probably aware of Pasteur's 1857 preliminary works. With both scientists claiming priority on the discovery, a dispute, extending to several areas, lasted throughout their lives.[103][104]

However, Béchamp was on the losing side, as the BMJ obituary remarked: His name was "associated with bygone controversies as to priority which it would be unprofitable to recall".[105] Béchamp proposed the incorrect theory of microzymes. According to K. L. Manchester, anti-vivisectionists and proponents of alternative medicine promoted Béchamp and microzymes, unjustifiably claiming that Pasteur plagiarized Béchamp.[47]

Pasteur thought that succinic acid inverted sucrose. In 1860, Marcellin Berthelot isolated invertase and showed that succinic acid did not invert sucrose.[51] Pasteur believed that fermentation was only due to living cells. Hans Buchner discovered that zymase catalyzed fermentation, showing that fermentation was catalyzed by enzymes within cells.[106] Eduard Buchner also discovered that fermentation could take place outside living cells.[107]
Anthrax vaccine

Pasteur publicly claimed his success in developing the anthrax vaccine in 1881.[93] However, his admirer-turned-rival Toussaint was the one who developed the first vaccine. Toussaint isolated the bacteria that caused chicken cholera (later named Pasteurella in honour of Pasteur) in 1879 and gave samples to Pasteur who used them for his own works.[108] On July 12, 1880, Toussaint presented his successful result to the French Academy of Sciences, using an attenuated vaccine against anthrax in dogs and sheep.[109] Pasteur on grounds of jealousy contested the discovery by publicly displaying his vaccination method at Pouilly-le-Fort on 5 May 1881.[110] Pasteur gave a misleading account of the preparation of the anthrax vaccine used in the experiment at Pouilly-le-Fort. He used potassium dichromate to prepare the vaccine.[9] The promotional experiment was a success and helped Pasteur sell his products, getting the benefits and glory.[110][111][112]
Experimental ethics

Pasteur experiments are often cited as against medical ethics, especially on his vaccination of Meister. He did not have any experience in medical practice, and more importantly, a medical license. This is often cited as a serious threat to his professional and personal reputation.[113][114] His closest partner Émile Roux, who had medical qualifications, refused to participate in the clinical trial, likely because he considered it unjust.[92] However, Pasteur executed vaccination of the boy under the close watch of practising physicians Jacques-Joseph Grancher, head of the Paris Children's Hospital's paediatric clinic, and Alfred Vulpian, a member of the Commission on Rabies. He was not allowed to hold the syringe, although the inoculations were entirely under his supervision.[91] It was Grancher who was responsible for the injections, and he defended Pasteur before the French National Academy of Medicine in the issue.[115]

Pasteur has also been criticized for keeping secrecy of his procedure and not giving proper pre-clinical trials on animals.[44] Pasteur stated that he kept his procedure secret in order to control its quality. He later disclosed his procedures to a small group of scientists. Pasteur wrote that he had successfully vaccinated 50 rabid dogs before using it on Meister.[116][117][118] According to Geison, Pasteur's laboratory notebooks show that he had vaccinated only 11 dogs.[44]

Meister never showed any symptoms of rabies,[92] but the vaccination has not been proved to be the reason. One source estimates the probability of Meister contracting rabies at 10%.[80]
Awards and honours

Pasteur was awarded 1,500 francs in 1853 by the Pharmaceutical Society for the synthesis of racemic acid.[119] In 1856 the Royal Society of London presented him the Rumford Medal for his discovery of the nature of racemic acid and its relations to polarized light,[120] and the Copley Medal in 1874 for his work on fermentation.[121] He was elected a Foreign Member of the Royal Society (ForMemRS) in 1869.[1]

The French Academy of Sciences awarded Pasteur the 1859 Montyon Prize for experimental physiology in 1860,[34] and the Jecker Prize in 1861 and the Alhumbert Prize in 1862 for his experimental refutation of spontaneous generation.[67][122] Though he lost elections in 1857 and 1861 for membership to the French Academy of Sciences, he won the 1862 election for membership to the mineralogy section.[123] He was elected to permanent secretary of the physical science section of the academy in 1887 and held the position until 1889.[124]

In 1873 Pasteur was elected to the Académie Nationale de Médecine[125] and was made the commander in the Brazilian Order of the Rose.[126] In 1881 he was elected to a seat at the Académie française left vacant by Émile Littré.[127] Pasteur received the Albert Medal from the Royal Society of Arts in 1882.[128] In 1883 he became foreign member of the Royal Netherlands Academy of Arts and Sciences.[129] On June 8, 1886, the Ottoman Sultan Abdul Hamid II awarded Pasteur with the Order of the Medjidie (I Class) and 10000 Ottoman liras.[130] Pasteur won the Leeuwenhoek Medal from the Royal Netherlands Academy of Arts and Sciences for his contributions to microbiology in 1895.[131]

Pasteur was made a Chevalier of the Legion of Honour in 1853, promoted to Officer in 1863, to Commander in 1868, to Grand Officer in 1878 and made a Grand Cross of the Legion of Honor in 1881.[132][128]


12 December 2017

Europe has four more Galileo navigation satellites in the sky following their launch on an Ariane 5 rocket. After today’s success, only one more launch remains before the Galileo constellation is complete and delivering global coverage.

Ariane 5, operated by Arianespace under contract to ESA, lifted off from Europe’s Spaceport in Kourou, French Guiana at 18:36 GMT (19:36 CET, 15:36 local time), carrying Galileo satellites 19–22. The first pair of 715 kg satellites was released almost 3 hours 36 minutes after liftoff, while the second pair separated 20 minutes later.

They were released into their target 22 922 km-altitude orbit by the dispenser atop the Ariane 5 upper stage. In the coming days, this quartet will be steered into their final working orbits. There, they will begin around six months of tests – performed by the European Global Navigation Satellite System Agency (GSA) – to check they are ready to join the working Galileo constellation.
Four Galileos on Ariane 5

This mission brings the Galileo system to 22 satellites. Initial Services began almost a year ago, on 15 December 2016.

“Today’s launch is another great achievement, taking us within one step of completing the constellation,” remarked Jan Wörner, ESA’s Director General.

“It is a great achievement of our industrial partners OHB (DE) and SSTL (GB) for the satellites, as well as Thales-Alenia-Space (FR, IT) and Airbus Defense and Space (GB, FR) for the ground segment and all their subcontractors throughout Europe, that Europe now has a formidable global satellite navigation system with remarkable performance.”
Galileos atop Ariane 5

Paul Verhoef, ESA’s Director of Navigation, added: “ESA is the design agent, system engineer and procurement agent of Galileo on behalf of the European Commission. Galileo is now an operating reality, so, in July, operational oversight of the system was passed to the GSA.

“Accordingly, GSA took control of these satellites as soon as they separated from their launcher, with ESA maintaining an advisory role. This productive partnership will continue with the next Galileo launch, by Ariane 5 in mid-2018.

“Meanwhile, ESA is also working with the European Commission and GSA on dedicated research and development efforts and system design to begin the procurement of the Galileo Second Generation, along with other future navigation technologies.”

Next year’s launch of another quartet will bring the 24‑satellite Galileo constellation to the point of completion, plus two orbital spares.
Lowering the fairing

About Galileo

Galileo is Europe’s civil global satellite navigation system. It will allow users worldwide to know their exact position in time and space with great precision and reliability. Once complete, the system will consist of 24 operational satellites and the ground infrastructure for the provision of positioning, navigation and timing services.

The Galileo programme is funded and owned by the EU. The European Commission has the overall responsibility for the programme, managing and overseeing the implementation of all programme activities.

Galileo’s deployment, the design and development of the new generation of systems and the technical development of infrastructure are entrusted to ESA. The definition, development and in-orbit validation phases were carried out by ESA, and co‑funded by ESA and the European Commission.

GSA is ensuring the uptake and security of Galileo. Galileo operations and provision of services were entrusted to the GSA in July 2017.
Galileo constellation

Learn more about Galileo at:


About the European Space Agency

The European Space Agency (ESA) provides Europe’s gateway to space.

ESA is an intergovernmental organisation, created in 1975, with the mission to shape the development of Europe’s space capability and ensure that investment in space delivers benefits to the citizens of Europe and the world.

ESA has 22 Member States: Austria, Belgium, the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Luxembourg, the Netherlands, Norway, Poland, Portugal, Romania, Spain, Sweden, Switzerland and the United Kingdom. Slovenia is an Associate Member.

ESA has established formal cooperation with six Member States of the EU. Canada takes part in some ESA programmes under a Cooperation Agreement.

By coordinating the financial and intellectual resources of its members, ESA can undertake programmes and activities far beyond the scope of any single European country. It is working in particular with the EU on implementing the Galileo and Copernicus programmes as well as with Eumetsat for the development of meteorological missions.

ESA develops the launchers, spacecraft and ground facilities needed to keep Europe at the forefront of global space activities.

Today, it develops and launches satellites for Earth observation, navigation, telecommunications and astronomy, sends probes to the far reaches of the Solar System and cooperates in the human exploration of space. ESA also has a strong applications programme developing services in Earth observation, navigation and telecommunications.

Learn more about ESA at www.esa.int

For further information, please contact:
ESA Media Relations Office
Email: media@esa.int
Tel: +33 1 53 69 72 99


La Maison Dieu est le seizième arcane majeur du tarot de Marseille.

Au cours du temps, le graphisme de cette carte a beaucoup évolué.

Pour Jacques Viéville (vers 1650), elle représente un arbre sous lequel un berger et son troupeau s'abritent du soleil. Dans son édition originale, le berger, les bras écartés la tête levée vers le ciel, semble recevoir une pluie, ou manne céleste, détail qui est resté dans le tarot de Marseille.

Jean Noblet (Paris, milieu du XVIIe siècle) et Jean Dodal (Lyon, 1715) optent pour la représentation d'une tour dont la coiffe ouverte laisse échapper une flamme ascendante en direction du soleil, deux hommes tombant de cette tour.

Enfin Nicolas Conver (Marseille, 1761) propose la version de la carte telle qu'elle est reproduite aujourd'hui, à savoir une représentation basée sur celle de Dodal, à ceci près que la flamme est représentée comme descendante et que le soleil a quasiment disparu.
Description et symbolisme

Elle représente soit l'humilité, soit l'égo anéanti par l'épreuve : Destruction violente des masques et autres montages fallacieux. Salvatrice, le défi d'humilité peut être douloureux.

Si la carte apparaît à l'envers, au contraire, elle signifie que l’égo est nécessaire, qu'il y a latence dans l'évolution. On peut s'ampouler d'une construction, toutefois elle protège toujours quelque chose.

Ce symbolisme de La Maison Dieu n'est pas sans rappeler celui de la Tour de Babel. Effectivement dans la tradition biblique, la Tour de Babel fut toujours considérée comme un projet ambitieux envers lequel Dieu exerça son veto (symbolisé par la foudre dans l'iconographie de La Maison Dieu).

D'autre part le nom même de Babel, nom hébreu de Babylone fut tiré de l'Akkadien bab-ili(m) signifiant « la Porte du Dieu ». On peut donc penser que le dieu de la Tour de Babel ou de La Maison Dieu n'est pas le vrai Dieu. Mais peut-être son opposé, c'est-à-dire Mammon. Ce dieu personnifiant la richesse. La traduction du mot en témoigne car en araméen le mot signifie « riche ». Donc la Tour de Babel ou la Maison Dieu seraient des allégories du capitalisme ou de l'impérialisme selon une dénomination plus biblique.

D'ailleurs la couronne sur la tour est bien là pour l'illustrer, car étant celle de Nimrod le premier roi du monde et fondateur du premier des empires selon la Bible. C'est à l'époque de la Tour de Babel qu'il régna. Son nom serait issue de l'hébreu « maradh » qui dérive du verbe « mered » signifiant « se rebeller ».

En conclusion la carte de La Maison Dieu renferme les idées d'orgueil, de richesse, d'impérialisme et de rébellion, ainsi que de chute à la suite d'une faute commise. Et si la tour est remplacée par un arbre dans le tarot de Viéville, c'est bien en rapport avec l'idée de chute. L'arbre de la connaissance du bien et du mal étant la cause de la chute adamique et à l'origine du péché originel.

Mais il y a aussi une interprétation alchimique intéressante à signaler. Le fait que le mot "taroté" se disait autrefois "d'une superficie dorée à la feuille, lorsqu'elle était poinçonnée ou gravée avec un stylet ou un poinçon pour imprimer un dessin sur l'or. Les fonds des premiers tarots enluminés étaient obtenus de cette façon." 1 a certainement éveillé l'attention des chercheurs. Il faut en effet remarquer que l'on parle des "lames" , et non des "cartes" du tarot. LA MAISON DIEV, qui en cartomancie vulgaire présage (malgré son nom) une catastrophe redoutable (telle par exemple que l'a redessinée Oswald Wirth), est interprétée comme étant un athanor alchimique dont le couvercle se soulève, et devant laquelle danse le disciple (guidé par le geste et la parole du maître). "Nous voyons en réalité une tour dont le couvercle se soulève sans difficulté, comme un couvercle. Il n'est donc pas question ici de tour foudroyée. C'est tout simplement l'athanor ou four des alchymistes au moment où se produit ce qu'on appelle la première conjonction qui est le don de Dieu. Ce qui pénètre dans la tour, c'est ce nitre coruscant qui va devenir le Mercure des Philosophes. L'athanor a été souvent décrit par les auteurs anciens comme une tour ronde de briques cimentées. Ne voit-on pas, par les trois fenêtres de cette tour, qu'elle se remplit de ce grand air qu'est l'azur céleste ? C'est là le noble sang bleu qui va peu à peu se figer en miel de charité.2

↑ G. Mandel, Les tarots des Visconti, Paris, Vilo, 1975
↑ Emmanuel d'Hooghvorst, Le Fil de Pénélope, Grez-Doiceau, Beya Editions, novembre 2009, 446 p. (ISBN 978-2-9600575-3-9), p. 250


Revenir en haut Aller en bas
Voir le profil de l'utilisateur http://www.atelier-yannistignard.com
yanis la chouette

Nombre de messages : 9682
Localisation : http://yanis.tignard.free.fr/
Date d'inscription : 09/11/2005



Marie Pasteur, née Laurent (15 January 1826 in Clermont-Ferrand, France – 28 September 1910 in Paris), was the scientific assistant and co-worker of her spouse, the famous French chemist and bacteriologist Louis Pasteur.

Marie Pasteur was one of the daughters of the Rector of the Strasbourg Academy. She married in Strasbourg 29 May 1849, aged 23, to Louis Pasteur, aged 26.

Marie worked as a secretary and science writer to her spouse and served as his amanuensis. She was his active assistant in his scientific experiments. She worked with him on expanding his first researches, around 1848, on the remarks previously made by Mitscherlich on the different optical properties concerning polarized light of tartaric acid when it came from natural wines, wine lees and when it was synthesized in a laboratory. The students and colleagues of Louis Pasteur acknowledged the importance she had for him in his work as his assistant. She grew the silkworms he needed for his experiment with their diseases, and she took care of the children he tried his famous experimental treatment on. She moved with him to his quarters at the Pasteur institute, and continued to live there after his death.

It seems that for years afterward, famous crystallographer, physicist and mathematician Jean Baptiste Biot, Madame Marie Pasteur and Louis' father, Jean Joseph cooperated in providing Louis with moral support. For instance, in a letter by Biot to Louis father: "your son is ours also and we share with Marie all our love for him, too". There was also philosopher Charles Chappuis in this support network around Louis.

Their eldest daughter, Jeanne, died from typhoid fever, aged 9, at Arbois. Then, in 1865, 2-year-old Camille also died of typhus, followed by 12-and-a-half-year-old Cécile on 23 May 1866. Only Jean Baptiste and Marie Louise lived to be adults. Jean Baptiste would be a soldier in the Franco-Prussian War between France and Prussia.

Marie Pasteur was buried in the crypt of the Institute Pasteur.

The Biographical Dictionary of Women in Science: Pioneering Lives from Ancient Times to the Mid-20th Century (2 Vol. Set) by Marilyn Bailey OGILVIE (Editor), Joy Dorothy HARVEY(Editor), Taylor and Francis, Kindle Edition, (wireless edition), File Size: 2779 KB, Print Length: 1499 pages
The Biographical Dictionary of Women in Science: L-Z by Marilyn Bailey Ogilvie,Joy Dorothy Harvey

Born Marie Laurent
January 15, 1826
Died September 28, 1910 (aged 84)
Nationality French
Occupation scientific assistant
Known for Spouse of Louis Pasteur


News | December 12, 2017
Bright Areas on Ceres Suggest Geologic Activity.

If you could fly aboard NASA's Dawn spacecraft, the surface of dwarf planet Ceres would generally look quite dark, but with notable exceptions. These exceptions are the hundreds of bright areas that stand out in images Dawn has returned. Now, scientists have a better sense of how these reflective areas formed and changed over time -- processes indicative of an active, evolving world.

"The mysterious bright spots on Ceres, which have captivated both the Dawn science team and the public, reveal evidence of Ceres' past subsurface ocean, and indicate that, far from being a dead world, Ceres is surprisingly active. Geological processes created these bright areas and may still be changing the face of Ceres today," said Carol Raymond, deputy principal investigator of the Dawn mission, based at NASA's Jet Propulsion Laboratory in Pasadena, California. Raymond and colleagues presented the latest results about the bright areas at the American Geophysical Union meeting in New Orleans on Tuesday, Dec. 12.

Different Kinds of Bright Areas

Since Dawn arrived in orbit at Ceres in March 2015, scientists have located more than 300 bright areas on Ceres. A new study in the journal Icarus, led by Nathan Stein, a doctoral researcher at Caltech in Pasadena, California, divides Ceres' features into four categories.

The first group of bright spots contains the most reflective material on Ceres, which is found on crater floors. The most iconic examples are in Occator Crater, which hosts two prominent bright areas. Cerealia Facula, in the center of the crater, consists of bright material covering a 6-mile-wide (10-kilometer-wide) pit, within which sits a small dome. East of the center is a collection of slightly less reflective and more diffuse features called Vinalia Faculae. All the bright material in Occator Crater is made of salt-rich material, which was likely once mixed in water. Although Cerealia Facula is the brightest area on all of Ceres, it would resemble dirty snow to the human eye.

› DOWNLOAD VIDEO The Bright Stuff: New NASA Dawn Findings at Ceres

More commonly, in the second category, bright material is found on the rims of craters, streaking down toward the floors. Impacting bodies likely exposed bright material that was already in the subsurface or had formed in a previous impact event.

Separately, in the third category, bright material can be found in the material ejected when craters were formed.

The mountain Ahuna Mons gets its own fourth category -- the one instance on Ceres where bright material is unaffiliated with any impact crater. This likely cryovolcano, a volcano formed bythe gradual accumulation of thick, slowly flowing icy materials, has prominent bright streaks on its flanks.

Over hundreds of millions of years, bright material has mixed with the dark material that forms the bulk of Ceres' surface, as well as debris ejected during impacts. That means billions of years ago, when Ceres experienced more impacts, the dwarf planet's surface likely would have been peppered with thousands of bright areas.

"Previous research has shown that the bright material is made of salts, and we think subsurface fluid activity transported it to the surface to form some of the bright spots," Stein said.

The Case of Occator

Why do the different bright areas of Occator seem so distinct from one another? Lynnae Quick, a planetary geologist at the Smithsonian Institution in Washington, has been delving into this question.

The leading explanation for what happened at Occator is that it could have had, at least in the recent past, a reservoir of salty water beneath it. Vinalia Faculae, the diffuse bright regions to the northeast of the crater's central dome, could have formed from a fluid driven to the surface by a small amount of gas, similar to champagne surging out of its bottle when the cork is removed.

In the case of the Vinalia Faculae, the dissolved gas could have been a volatile substance such as water vapor, carbon dioxide, methane or ammonia. Volatile-rich salty water could have been brought close to Ceres' surface through fractures that connected to the briny reservoir beneath Occator. The lower pressure at Ceres' surface would have caused the fluid to boil off as a vapor. Where fractures reached the surface, this vapor could escape energetically, carrying with it ice and salt particles and depositing them on the surface.

Cerealia Facula must have formed in a somewhat different process, given that it is more elevated and brighter than Vinalia Faculae. The material at Cerealia may have been more like an icy lava, seeping up through the fractures and swelling into a dome. Intermittent phases of boiling, similar to what happened when Vinalia Faculae formed, may have occurred during this process, littering the surface with ice and salt particles that formed the Cerealia bright spot.

Quick's analyses do not depend on the initial impact that formed Occator. However, the current thinking among Dawn scientists is that when a large body slammed into Ceres, excavating the 57-mile-wide (92-kilometer-wide) crater, the impact may have also created fractures through which liquid later emerged.

"We also see fractures on other solar system bodies, such as Jupiter's icy moon Europa," Quick said. "The fractures on Europa are more widespread than the fractures we see at Occator. However, processes related to liquid reservoirs that might exist beneath Europa's cracks today could be used as a comparison for what may have happened at Occator in the past."

As Dawn continues the final phase of its mission, in which it will descend to lower altitudes than ever before, scientists will continue learning about the origins of the bright material on Ceres and what gave rise to the enigmatic features in Occator.

The Dawn mission is managed by JPL for NASA's Science Mission Directorate in Washington. Dawn is a project of the directorate's Discovery Program, managed by NASA's Marshall Space Flight Center in Huntsville, Alabama. UCLA is responsible for overall Dawn mission science. Orbital ATK Inc., in Dulles, Virginia, designed and built the spacecraft. The German Aerospace Center, Max Planck Institute for Solar System Research, Italian Space Agency and Italian National Astrophysical Institute are international partners on the mission team. For a complete list of mission participants, visit:


More information about Dawn is available at the following sites:



News Media Contact
Elizabeth Landau
Jet Propulsion Laboratory, Pasadena, Calif.
(818) 354-6425




Revenir en haut Aller en bas
Voir le profil de l'utilisateur http://www.atelier-yannistignard.com
yanis la chouette

Nombre de messages : 9682
Localisation : http://yanis.tignard.free.fr/
Date d'inscription : 09/11/2005


Clermont-Ferrand (French pronunciation: ​[klɛʁmɔ̃ fɛʁɑ̃], Auvergnat Clharmou[3][4], Latin: Augustonemetum) is a city and commune of France, in the Auvergne-Rhône-Alpes region, with a population of 141,569 (2012).[2] Its metropolitan area had 467,178 inhabitants at the 2011 census. It is the prefecture (capital) of the Puy-de-Dôme department. Olivier Bianchi is its current mayor.

Clermont-Ferrand sits on the plain of Limagne in the Massif Central and is surrounded by a major industrial area. The city is famous for the chain of volcanoes, the Chaîne des Puys surrounding it. The famous dormant volcano Puy de Dôme (10 kilometres (6 miles) from the city) is one of the highest of these and well known for the telecommunication antennas that sit on its top and are visible from far away.

Clermont-Ferrand is also famous for hosting the Clermont-Ferrand International Short Film Festival (Festival du Court-Métrage de Clermont-Ferrand), one of the world's leading international festivals for short films, as well as the corporate headquarters of Michelin, the global tyre company created more than 100 years ago in the city.


Clermont-Ferrand's first name was Augusta Nemetum. It was born on the central knoll where the cathedral is situated today, known then as Nemossos. It overlooked the capital of Gaulish Avernie. The fortified castle of Clarus Mons gave its name to the whole town in 848, to which the small episcopal town of Montferrand was attached in 1731, together taking the name of Clermont-Ferrand. The old part of Clermont is delimited by the route of the ramparts, as they existed at the end of the Middle Ages. The town of Clermont-Ferrand came about with the joining together of two separate towns, Clermont and Montferrand, which was decreed by Louis XIII and confirmed by Louis XV.[5]
Prehistoric and Roman
Statue of Vercingétorix by Frédéric Auguste Bartholdi on the main square of the city

Clermont ranks among the oldest cities of France. The first known mention was by the Greek geographer Strabo, who called it the "metropolis of the Arverni" (meaning their oppidum, civitas or tribal capital). The city was at that time called Nemessos – a Gaulish word for a sacred forest, and was situated on the mound where the current cathedral of Clermont-Ferrand has been constructed. It was somewhere in the area around Nemossos that the Arverni chieftain Vercingetorix (later to head a unified Gallic resistance to Roman invasion under Julius Caesar) was born in around 72 BC. Also, Nemossos was situated not far from the plateau of Gergovia, where Vercingetorix pushed back the Roman assault at the Battle of Gergovia in 52 BC. After the Roman conquest, the city became known as Augustonemetum sometime in the 1st century[BC or AD?], a name which combined its original Gallic name with that of the Emperor Augustus. Its population was estimated at 15,000–30,000 in the 2nd century, making it one of the largest cities of Roman Gaul. It then became Arvernis in the 3rd century (taking its name, like other Gallic cities in this era, from the people who lived within its walls), and expanded until the mid 3rd century.
Early Middle Ages

The city became the seat of a bishop in the 5th century, at the time of the bishop Namatius or Saint Namace, who built a cathedral here described by Gregory of Tours. Clermont went through a dark period after the disappearance of the Roman Empire and during the whole High Middle Ages, marked by pillaging by the peoples who invaded Gaul. Between 471 and 475, Auvergne was often the target of Visigothic expansion, and the city was frequently besieged, including once by Euric. Although defended by Sidonius Apollinaris, at the head of the diocese from 468 to 486, and the patrician Ecdicius, the city was ceded to the Visigoths by emperor Julius Nepos in 475 and became part of the Visigothic kingdom until 507. A generation later, it became part of the Kingdom of the Franks. On 8 November 535 the first Council of Clermont opened at Arvernis (Clermont), with fifteen bishops participating, including Caesarius of Arles, Nizier of Lyons (bishop of Trier) and Saint Hilarius, bishop of Mende. Sixteen decrees were made there, notably the second canon that recalls that the granting of episcopal dignity must be according to the merits and not as a result of intrigues.

In 570, Bishop Avitus left the Jews of his town (who numbered over 500) the alternatives of baptism or expulsion.[6]

In 848, the city was renamed Clairmont, after the castle Clarus Mons. During this era, it was an episcopal city ruled by its bishop. Clermont was not spared by the Vikings at the time of the weakening of the Carolingian Empire: it was ravaged by the Normans under Hastein or Hastingen in 862 and 864 and, while its bishop Sigon carried out reconstruction work, again in 898 (or 910, according to some sources). Bishop Étienne II built a new Roman cathedral on the site of the current cathedral, consecrated in 946 but (apart from the towers, only replaced by the current ones in the 19th century, and some parts of the crypt, still visible) destroyed to build the current Gothic cathedral.
Middle Ages
Galeries of Jaude

Clermont was the starting point of the First Crusade, in which Christendom sought to free Jerusalem from Muslim domination: Pope Urban II preached the crusade there in 1095, at the Second Council of Clermont. In 1120, following repeated crises between the counts of Auvergne and the bishops of Clermont and in order to counteract the clergy’s power, the counts founded the rival city of Montferrand on a mound next to the fortifications of Clermont, on the model of the new cities of the Midi springing up in the 12th and 13th centuries. Until the early modern period, the two remained separate cities: Clermont, an episcopal city; Montferrand, a comital one.
Early Modern and Modern eras

Clermont became a royal city in 1551, and in 1610, the inseparable property of the Crown. On 15 April 1630 the Edict of Troyes (the First Edict of Union) forcibly joined the two cities of Clermont and Montferrand. This union was confirmed in 1731 by Louis XV with the Second Edict of Union. At this time, Montferrand was no more than a satellite city of Clermont, in which condition it remained until the beginning of the 20th century. Wishing to retain its independence, Montferrand made three demands for independence, in 1789, 1848, and 1863.

In the 20th century, construction of the Michelin factories and of city gardens, which shaped the modern Clermont-Ferrand, definitively reunited Clermont and Montferrand. But even today, although the two cities have been amalgamated, one may find in Clermont-Ferrand two distinct downtowns, and Montferrand still retains a strong identity.

Clermont-Ferrand's most famous public square is Place de Jaude, on which stands a grand statue of Vercingetorix sitting imperiously on a horse and holding a sword. The inscription reads: J'ai pris les armes pour la liberté de tous (I took up arms for the liberty of all). This statue was sculpted by Frédéric Bartholdi, who also created the Statue of Liberty.


Title 3D-printed satellite imager design
Released 13/12/2017 12:44 am
Copyright TNO

Weirdly organic in appearance, this prototype is the first outcome of an ESA project to develop, manufacture and demonstrate an optical instrument for space with 3D printing.

A two-mirror telescope derived from the European-made Ozone Monitoring Instrument now flying on NASA’s Aura satellite, it was not so much designed as grown, with the instrument’s design requirements put through ‘topology optimisation’ software to come up with the best possible shape.

This prototype was developed for ESA by a consortium led by OHB System in Germany, with TNO in the Netherlands – original designer of Aura’s version – Fraunhofer IFAM, IABG and Materialise in Germany and SRON, the Netherlands Institute for Space Research.

This first ‘breadboard’ prototype has been printed in liquid photopolymer plastic, then spray-painted. The final version would be printed in metal instead. The project is intended to culminate in testing a working instrument in a simulated space environment.

The project is being backed through ESA’s General Support Technology Programme, to hone promising technologies to be ready for space and global markets.
Id 388027


ESA astronaut Paolo Nespoli will return to Earth on 14 December after his third mission to the International Space Station. Paolo and crewmates Randy Bresnik of NASA and Sergei Ryazansky of Roscosmos will return in their Soyuz MS-05 spacecraft. Watch the events from farewell to touchdown live by tuning in at these times:

01:30 GMT (02:30 CET): farewells and hatch closure. Hatch closure scheduled for 02:00 GMT (03:00 CET)
04:30 GMT (05:30 CET): undocking of Soyuz MS-05 spacecraft. Undocking scheduled for 05:16 GMT (06:16 CET)
07:15 GMT (08:15 CET): reentry and landing coverage. First thruster firing to brake and reenter atmosphere scheduled for 07:44 GMT (08:44 CET). Touchdown in Kazakhstan expected at 08:38 GMT (09:38 CET)

The ride home from the International Space Station will see the trio brake from 28 800 km/h to a standstill at touchdown in barely three hours.

Paolo completed more than 60 experiments during his Vita mission, which stands for Vitality, Innovation, Technology and Ability.

His body was itself an arena for research: his eyes, headaches, sleeping patterns and eating habits were monitored to learn more about how humans adapt to life in space.

Temperature recordings, muscle exercises and plenty of blood and saliva samples will add to the picture and prepare humans for missions further from Earth.


Revenir en haut Aller en bas
Voir le profil de l'utilisateur http://www.atelier-yannistignard.com
yanis la chouette

Nombre de messages : 9682
Localisation : http://yanis.tignard.free.fr/
Date d'inscription : 09/11/2005


The Pasteur Institute (French: Institut Pasteur) is a French non-profit private foundation dedicated to the study of biology, micro-organisms, diseases, and vaccines. It is named after Louis Pasteur, who made some of the greatest breakthroughs in modern medicine at the time, including pasteurization and vaccines for anthrax and rabies. The institute was founded on June 4, 1887, and inaugurated on November 14, 1888.

For over a century, the Institut Pasteur has been at the forefront of the battle against infectious disease. This worldwide biomedical research organization based in Paris was the first to isolate HIV, the virus that causes AIDS, in 1983. Over the years, it has been responsible for breakthrough discoveries that have enabled medical science to control such virulent diseases as diphtheria, tetanus, tuberculosis, poliomyelitis, influenza, yellow fever, and plague.

Since 1908, eight Institut Pasteur scientists have been awarded the Nobel Prize for medicine and physiology, and the 2008 Nobel Prize in Physiology or Medicine was shared between two Pasteur scientists.

Institut Pasteur in Bandung, Dutch East Indies

The Institut Pasteur was founded in 1887 by Louis Pasteur, the famous French chemist and microbiologist. He was committed both to basic research and its practical applications. As soon as his institute was created, Pasteur brought together scientists with various specialties. The first five departments were directed by two normaliens (graduates of the École Normale Supérieure): Émile Duclaux (general microbiology research) and Charles Chamberland (microbes research applied to hygiene), as well as a biologist, Ilya Ilyich Mechnikov (morphological microbe research) and two physicians, Jacques-Joseph Grancher (rabies) and Emile Roux (technical microbe research). One year after the inauguration of the Institut Pasteur, Roux set up the first course of microbiology ever taught in the world, then entitled Cours de Microbie Technique (Course of microbe research techniques).

Pasteur's successors have sustained this tradition, and it is reflected in the Institut Pasteur's unique history of accomplishment:

Emile Roux and Alexandre Yersin discovered the mechanism of action of Corynebacterium diphtheriae and how to treat diphtheria with antitoxins;
Alexandre Yersin discovered in 1894 the pathogen of bubonic plague, Yersinia pestis;
Paul-Louis Simond discovered in 1898 the role of the flea in the transmission of plague;
Albert Calmette and Camille Guérin discovered how to culture the tuberculosis bacillus, Mycobacterium tuberculosis (so called BCG or Bacillus Calmette-Guérin) at Institut Pasteur de Lille and developed in 1921 the first effective antituberculosis vaccine;
Alphonse Laveran got the 1907 Nobel Prize for his research on the role of protozoans as disease agents (notably, his discovery of the malaria hematozoon)
Ilya Ilyich Mechnikov received the Nobel Prize in 1908 for contributions to scientific understanding of the immune system
Constantin Levaditi and Karl Landsteiner demonstrated in 1910 that poliomyelitis is due to a filterable virus;
Félix d'Herelle discovered in 1917 the bacteriophage, a virus that spread only inside bacteria;
Jules Bordet received the Nobel prize in 1919 for his discoveries on immunity, especially the implication of antibodies and the mechanisms of action of the complement;
Charles Nicolle received the Nobel prize in 1928 for unraveling the mystery of how typhus is transmitted, especially the role of the louse;
Jean Laigret developed in 1932 the first vaccine for yellow fever;
André Lwoff established in 1951 the existence of proviruses, a work honored by the 1965 Nobel Prize in Physiology or Medicine
Jacques Monod and Francois Jacob discovered the mechanism of genes' transcription regulation, a work honored by the 1965 Nobel Prize in Physiology or Medicine
Pierre Lépine developed in 1955 one of the first anti-polio vaccines
Jean-Pierre Changeux isolated in 1970 the first receptor to a neurotransmitter, the acetylcholine receptor.
Luc Montagnier, Françoise Barré-Sinoussi and colleagues discovered the two HIV viruses that cause AIDS, in 1983 and 1985, was honored by the 2008 Nobel Prize in Physiology or Medicine

The biggest mistake by the Institute was ignoring a dissertation by Ernest Duchesne on the use of Penicillium glaucum to cure infections in 1897. The early exploitation of his discovery might have saved millions of lives, especially in World War I.

A new age of preventive medicine in France was made possible by such developments from the Institut Pasteur as vaccines for tuberculosis, diphtheria, tetanus, yellow fever, poliomyelitis, and hepatitis B. The discovery and use of sulfonamides in treating infections was another breakthrough. Some researchers won fame by discovering antitoxins and Daniel Bovet received the 1957 Nobel Prize for his discoveries on synthetic anti-histamines and curarizing compounds.

Since World War II, Pasteur researchers have sharply focused on molecular biology. Their achievements were recognized in 1965, when the Nobel Prize was shared by François Jacob, Jacques Monod and André Lwoff for their work on the regulation of viruses. In 1985, the first human vaccine obtained by genetic engineering from animal cells, the vaccine against hepatitis B, was developed by Pierre Tiollais and collaborators.
The building hosting the Museum and the funeral chapel of Pasteur
The Institute's opening

Although the center against rabies, directed by Jacques-Joseph Grancher and Émile Roux was more than functional, it became so overcrowded that it became necessary to build a structure that Pasteur had been calling with the name “Institute Pasteur” long before it was even built. Since Pasteur could not, for health reasons, do it himself, he delegated the task of the project and of creating the new building, situated on rue Dutot, to two of his most trusted colleagues, Grancher and Emile Duclaux.[1]:65

From the beginning the Institute experienced some economical difficulties that it was able to overcome thanks to the help of the government, some foreign rulers and Madame Boucicaut, but this aid would not in any way restrain its independence, therefore respecting Pasteur’s most important prerogative. The million francs left unused would not be sufficient to provide for the Institute’s needs for long, but the prestige and the social benefits it would bring to France justified and motivated the subsidy it would receive; also the money brought in from selling the vaccines in France and in the rest of the world would help in supporting it. In 1888 this foundation, which had obtained the full approval from the government, began to function, and from the beginning it was involved in the development and changes that France underwent during the last decades of the 19th century.[1]:68

The statutes drawn by Pasteur and later approved by Duclaux and Grancher define, besides its absolute freedom and independence, the Institute's internal structure: a rabies division controlled by Grancher, an anthrax one in Chamberland’s hands, who also supervised the department of microbiology, while Emile Roux dealt with microbial methods applied to medicine.
The Institute during World War I and World War II

During the First World War the Institute was not only involved in the prevention of sanitary risks but also had to deal with the demands of the moment. The most urgent matter was to vaccinate the troops against typhoid fever, easily contracted by the soldiers who often had no choice but to drink from small streams or puddles from the last rain. By September 1914, the Institute was able to provide 670,000 doses of the needed vaccine and continued to produce it throughout the conflict. It is important to note that the war brought to light germs that during times of peace were concealed deep within the soil or in pockets of putrefaction and therefore it revealed the true nature and severity of some types of pathologens that would otherwise have remained unknown. That's how Michel Weinberg, Metchnikoff’s scholar, disclosed the complex etiology of gas gangrene and created a vaccine for each one of the anaerobes associated with it.[1]:147[2] The First World War involved science in warfare: a movement of active participation arose among researchers who felt the need to help France win the war. This is why Gabriel Bertrand, with Roux’s authorization, crafted a grenade based on chloropicrin and Fourneau discovered the chemical reaction that led to the formation of methylarsine chloride whose effects are even worse than the ones of other poisonous gases used during the war.

In 1938 the Institute, despite its relative poverty, built a biochemical division and another one dedicated to cellular pathology, whose direction was entrusted to the hands of Boivin (who went on to discover endotoxins that are contained in the germ's body and are freed after its death). During the same period, Andre Lwoff assumed the direction of a new microbial physiology branch built on rue Dutot.[1]:205 The general mobilization after France's declaration of war against Germany, in September 1939, emptied the Institute and significantly reduced its activities, as members of appropriate age and condition were recruited into the army, but the almost total absence of battles during the first months of the conflict helped maintain the sanitary situation on the front. After the occupation of France, the Germans never tried to gather information from the Institute’s research; their confidence in Germany’s advantage in this field decreased their curiosity, and their only interest was in the serums and vaccines that it could provide to their troops or the European auxiliaries they recruited. This relative freedom allowed the Institute to become, during the two years after the occupation, a great pharmacy for the Resistance thanks to the initiative of Vallery-Radot, Pasteur’s nephew. The Germans became suspicious of the Institute’s staff only after an outbreak of typhoid in a Wehrmacht division that was stationed near Paris before being sent to the Russian front.[1]:209–210 The cause of the epidemic was later found to be due to a member of the Institute stealing a culture of the germ responsible for the disease and, with the collaboration of an accomplice, infecting a large quantity of butter used to feed German troops. The fact that the epidemic spread after the Germans sold some of the butter to civilians was proof that the illness's breakout was not caused by local water quality. Afterwards, the German authorities ordered that the Institute’s stores containing microbial cultures could be opened only by authorized members; similar security problems also induced them to demand complete lists of the staff's names and functions; missing names caused the Germans to send two very valuable biologists, Dr. Wolmann and his wife, as well as other three lab assistants, to a concentration camp. The Institute was not a location for German entrenchment even during the battles for Paris’s liberation because of the honor and respect it commanded, as well as out of fear that involving it in any type of conflict might “free the ghosts of long defeated diseases”.[1]:213
The Institute's economical difficulties during the Seventies

At the end of 1973 the Institute’s economic status was so worrisome that its troubles aroused the public’s interest: no-one could believe that an institution which was to provide vaccines and serums for more that fifty million people could be undergoing such big financial problems, an institution that furthermore was believed to be under government protection – like the Bank of France – and therefore shielded from bankruptcy. The causes of the decadence that brought the Institute to financial ruins were numerous, but most of them were associated with its commercial and industrial activities and its management. Both the research and production branch had to endure the recoil caused by financial issues: the research branch didn't receive enough funds and the production branch, which was losing market ground to the new private labs, was immobilized by the antiquated mechanical equipment.

When in 1968, after disappearing for a long period, rabies reappeared in France, the Institute, which owed its original celebrity to this disease’s vaccine, was replaced by other pharmaceutical industries in the production of the vaccines; yet, despite the deficiencies in the organization's production branch, its members were able to produce, in 1968, over 400,000 doses of vaccine against the Hong Kong influenza.

In 1971 Jacques Monod announced a new era of modernization and development: this new awakening was symbolized by the construction of a new factory where all the production departments were to be reunited. Its construction cost forty-five million francs and the Government, impressed by the Institute’s will to change, granted it a sum of twenty million francs to bridge the deficit, followed by the people’s initiative to also accept a role in the division of the financial responsibilities.[1]:258


Title Galileo 19-22 - liftoff replay
Released: 12/12/2017
Length 00:03:10
Language English
Footage Type Live Footage
Copyright ESA/CNES/Arianespace

Europe’s 19th, 20th, 21th and 22nd Galileo satellites lifted off from Europe’s Spaceport in French Guiana atop an Ariane 5 launcher.

Galileo 19-22 replay - part 1

Galileo 19-22 replay - part 2


Revenir en haut Aller en bas
Voir le profil de l'utilisateur http://www.atelier-yannistignard.com
yanis la chouette

Nombre de messages : 9682
Localisation : http://yanis.tignard.free.fr/
Date d'inscription : 09/11/2005


The accomplishments of the Institute's members
Roux's cure against diphtheria and studies on syphilis
Production of antiserum at the Institut Pasteur in Paris

Not long after the Institute’s inauguration, Roux, now less occupied in the fight against rabies, resumed in a new lab and with the help of a new colleague, Yersin, his experiments on diphtheria. This disease used to kill thousands of children every year: an associated condition was commonly called croup, which created fake membranes in the small patients' throats, therefore killing them by suffocation. It was deservedly called “Horrible monster, sparrowhawk of the shadows” by Victor Hugo in his Art of being a grandfather. The painter Albert Gustaf Aristides Edelfelt made a famous painting portraying Pasteur in his laboratory while he was trying to cure this illness, which was fought at the times through procedures that were just as cruel as the illness itself.

Roux and Yersin grew the bacillus that causes it and studied, thanks to various experiments they did on rabbits, its pathogenic power and symptoms, like the paralysis of the respiratory muscles.[1]:73 It is this last consequence of the diphtheria that provided the two researchers with a valuable clue of the nature of the disease, since it is caused by an intoxication due to a toxin introduced into the organism by the bacillus, that while secreting this particular venom is able to multiply itself: they were therefore inclined to think that the bacillus owed its virulence to the toxin. After filtrating the microbial culture of the Corynebacterium diphtheriae and injecting it into the lab animals, they were able to observe all the typical signs of the sickness. Roux and Yersin established that they were dealing with a new type of bacillus, not only able to proliferate and abundantly reproduce itself, but also capable of spreading at the same time a powerful venom, and they deduced that it can play the role of antigen, that is if they could overcome the delicate moment of its injection, made especially dangerous by the toxin.[1]:74 Some German researchers had also discovered the diphtheria toxin and were trying to immunize some guinea pigs through the use of a vaccine: one of them, Von Behring, Robert Koch's student, stated that he was able to weaken small doses of the toxin. Nonetheless Roux was not convinced by this result, since no-one knew the collateral effects of the procedure, and preferred to use serotherapy since more than one lab study – like the one accomplished by Charles Richet – demonstrated that the serum of an animal vaccinated against the disease included the antibodies needed to defeat it. The anti-diphtheria serum which was able to agglutinate the bacteria and neutralize the toxin was supplied by a horse inoculated with the viral germs, and it was separated from the blood drawn from the horses’ jugular vein. Like it happened for his teacher with the anti-rabies vaccine, Roux needed to test the effectiveness of the product he elaborated, and endured all the stress and ethical dilemmas that the first use of such a risky but also groundbreaking procedure implied. To test the serum two groups of children were chosen from two different hospitals: in the first one, which received the serum, 338 out of 449 children survived, in the latter one, treated with the customary therapies, only 204 out of 520 survived. Once the results were made public by Le Figaro newspaper, a subscription fund was opened to raise the money needed to provide the Institute the number of horses necessary to produce enough serum to satisfy the national demand.[1]:82

After Duclaux’s death, Roux took his place as head of the Institute, and the last research he carried out was the one on syphilis, a dangerous disease because of its immediate effects and the hereditary repercussions that result from it. Despite Fournier’s considerable work, van Swieten’s liquid mercury was still the only known cure, although its results were doubtful and uncertain. The search for a stronger remedy against this disease was made more difficult because most animals are immune to it: it was thus not possible to experiment possible cures and study their likely side effects.[1]:128 The sexually transmittable Treponema pallidum (the syphilis germ), detected by two German biologists, Schaudinn and Hoffmann, affects only the human race – where it resides in sperm, ulceration and cancers that it is able to cause – and, as it will be later discovered, some anthropoid apes, especially chimpanzees. Both Roux and Metchnikoff, consequent to the discovery that this type of ape can be contaminated with the illness, contributed with their research in creating a vaccine, while Bordet and Wassermann elaborated a solution that was able to expose the germ’s presence in human blood. Even though it was not yet a completely reliable solution, it represented a noteworthy evolution compared to the previous medicines used against syphilis.[1]:129
Metchnikoff’s phagocytosis theory

Ilya Ilyich Mechnikov already announced the “principle of immunization” during his voluntary exile in Italy, where he went to undertake some studies, the results of which he had promptly communicated to Pasteur. The phagocytosis theory is based on the notion that phagocytes are cells that have the power to englobe foreign bodies – and above all bacteria – introduced inside an organism. German biologists opposed to his doctrine the humoral theory: they claimed to have found in Roux's serum some substances able to reveal the presence of microbes, and to ensure their destruction if properly stimulated. The German scientist Eduard Buchner referred to these substances as “alexine” and two other biologists, Von Behring and Kitasato, demonstrated their lytic power towards bacteria.[1]:83 In 1894 one of these scientist published the result of an experiment that appeared to completely refute Metchnikoff’s ideas: using the cholera vibrio, discovered ten years before by Robert Koch, as an antigen, Richard F. J. Pfeiffer introduced it in the abdomen of a guinea pig already vaccinated against this disease, and was able to observe the destruction of the vibrio in the local blood plasma, without the participation of the phagocytes. Not even this study was able to shake Metchnikoff’s belief and faith in his theory, and his ideas, as well as Pfeiffer’s and Buchner’s, would all contribute to the elaboration of the current theory of the immune system.
Yersin's studies on the plague

Yersin, after his research with Roux, abruptly left the Institute for personal reasons, without losing Pasteur’s benevolence, who never doubted that the young man was destined to great things in the scientific area and would contribute in spreading Pasteur's discoveries around the world. The news of a violent plague outburst in Yunman enabled Yersin to truly show and reach his potential as he was summoned, as Pasteur’s scholar, to conduct a microbiological research of the disease. The plague he had to deal with was the bubonic plague, which is recognizable most of the time through the abscesses, known as buboes, it provokes in its victims. Yersin looked for the germ responsible for the infection specifically in these plague-spots, tumors caused by the inflammation of the lymphatic glands which become black because of the necrosis of the tissue.[1]:91 After many microscopic exams he was able to state that in most of the cases the bubonic plague bacterium was located in these buboes; but in the meanwhile the Japanese scientist Kitasato also declared that he had isolated the bacterium, even though the description he provided was dissimilar to the one given by Yersin. Therefore, although at first named “Kitasato-Yersin bacillus” by the scientific community, the microbe will later assume only the latter’s name because the one identified by Kitasato, a type of streptococcus, cannot be found in the lymphatic glands. However it is Paul-Louis Simond who was the first to understand and describe the etiology of the plague and its modality of contamination: he observes all over the bodies of the people affected by it small flea-bites, which he also found on the bodies of the dead rats that were always linked to the plague, and then deduced that the fleas which carried the bacteria were its true vector or source, and that they transmitted the illness by jumping from the dead rats' bodies to the human ones and biting them.[1]:94
Paul-Louis Simond injecting a plague vaccine on the 4th of June 1898 in the Vishandas Hospital, Karachi
Calmette's and Guerin's anti-tuberculosis vaccine

By the beginning of the 20th century, the improvement of the general life conditions and the development of a more extensive conception of hygiene produced in France a slight regression in tuberculosis cases: nonetheless the Institute’s labs, like many other ones, kept trying to find among the Koch’s bacillus many singularities the one that would allow them to find an antidote to its terrible consequences. Right after he had discovered the bacillus, Koch had tried in vain to create a vaccine against it, however the injection of the filtrate he had prepared, later called tuberculin, had the effect of revealing who was phthisic from who wasn’t by causing in the latter—and not in the former—fever and light trembling.

The Institute’s newspaper was filled at the time with articles regarding tuberculosis, some of which written by Albert Calmette, who extended his research to a socio-professional category which was extremely affected by it, that is the miners in whom this disease is often anticipated or accompanied by silicosis and anchylostomiasis (caused by a small intestinal worm that creates a state of anemia propitious to tuberculosis).[1]:140 After finding a better solution to anchylostomiasis, he focused on creating a vaccine using the bacillus responsible for bovine tuberculosis, very similar to the human one, as it caused almost the same symptoms. Having observed that most actinomycetales are saprophytes, that is able to survive outside of living organisms, with the help of a veterinary, Camille Guerin, he attempted to create a special nutritious environment for the bacillus that, in time, altered its features by eliminating the virulence and leaving only the antigenic power. Both of the scientist knew that this arduous task would require a lot of effort and time, because it was necessary to act on a large number of generations to change the genetic foundation of a species, nevertheless the velocity of the bacteria’s reproduction allowed, since it was constantly monitored, to interfere with an important phase of its evolution. The environment deemed appropriate for the denaturation of the Mycobacterium bovis was a compost of potatoes cooked in the bile of an ox treated with glycerine, and Calmette re-inseminated it every three weeks for thirteen years, while checking for an enfeeblement of the pathogenic power of the bacillus. Having finally lost completely its virulence, the bovine tuberculosis germ grown with their method was the principal prophylactic weapon against human tuberculosis, and it helped to reduce considerably the frequency of this disease.

While experimenting on chimpanzees in Kindia, on which he was able to test exhaustively his vaccine, Calmette also discovered that it can notably weaken some leprosy manifestations – its bacillus presents some similarities with Koch’s.[1]:186
Calmette's work in Saigon

In Saigon Albert Calmette also created the first overseas branch of the Institute, where he produced an amount of smallpox and rabies vaccines sufficient to satisfy the needs of the population, and started a study on venomous snakes, particularly cobras. During these studies Calmette discovered that the power of the venom, as well as that of tetanus, could be annihilated by the use of alkaline hypochlorites, and was able therefore to create a serum, effective if injected right after the cobra’s bite. Back in France, he acquired enough snakes to continue his work and create serum for the local population.[1]:98
Nicolle's work on epidemic typhus

The scientist and writer Charles Nicolle while in Tunis studied how epidemic typhus – known for the red spots it left on sick people that disappeared before their death – was transmitted. His insight into the mode of transmission occurred while he was visiting the hospital: patients were washed and given clean clothes on admission, and no new cases occurred within the hospital. This made him realise that the vector of the disease were lice that were discarded with the patient's own clothes.[3] Nicolle managed to attract Hélène Sparrow to be Laboratory Chief in Tunis. She had worked with Rudolf Weigl who had developed a vaccine, and she was able to introduce this to Tunisia as the start of a public health programme to control the disease.[4] Nevertheless, three other scientists identified the bacterium responsible for the disease: Ricketts, Russell Morse Wilder (1885–1959), and Prowazek, who called it Rickettsia prowazekii.[1]:101
Chantemesse's typhoid vaccine

During the summer of 1900, the extremely hot weather and scarcity of the water supply in Paris, usually ensured by the Ourcq channel and by the de la Dhuis aqueduct, forced the authorities to pump water directly from the Seine, which, despite filtering, led to a sudden and alarming outbreak of typhoid cases in Paris. The cause of the disease, a bacillus that was discovered almost twenty years before by the German bacteriologist Karl Joseph Eberth and that looks like a bodyless spider, was constantly present in this river and not even pouring extensive quantities of ozone and of lime permanganate into its water was enough to exterminate the bacteria.[1]:111 The difficulty in creating a vaccine is caused by the nature of the germ’s endotoxins. Unlike diphtheria, which releases toxins via exocytotic secretion, typhoid pathogens encapsulate endotoxins which survive even after the death of the bacillus.

After working in the rabies division of Rue Vaquelin and studying the microbe that causes dysentery, André Chantemesse collaborated with a younger bacteriologist, Georges-Fernand Widal. Together they were able to immunize guinea pigs by inoculating them with heat-treated dead bacteria, calling into question the notion that only weakened, not dead, bacteria can be used to immunize.[1]:112 They concluded that a series of three or four early injections of such heat-inactivated bacteria can effectively inoculate against development of the disease, as the endotoxins alone are sufficient to trigger the production of antibodies.
Fourneau and the Laboratory of Medicinal Chemistry

Regarding curative medicine, it was in 1911 that it took off at the Institut Pasteur, when Ernest Fourneau created the Laboratory of Medicinal Chemistry, which he directed until 1944, and from which emerged numerous drugs, among which one can mention the first pentavalent arsenical treatment (Stovarsol), the first synthetic alpha-adrenoreceptor antagonist (Prosympal), the first antihistamine (Piperoxan), the first active drug on heart rate (Dacorene) or the first synthetic no-depolarising muscle relaxant (Flaxedil). The discovery of the therapeutic properties of sulfanilamide by Tréfouël, Nitti and Bovet, in the laboratory of Fourneau, paved the way for the sulfamidotherapy.[5][6]


Gaia's view of our galactic neighbours

13 December 2017
Measuring the positions and motions of more than a billion stars, ESA's Gaia mission will refine our knowledge about our place in the Universe, providing the best ever star chart of our Milky Way and its neighbouring galaxies.

Gaia's view of the Large Magellanic Cloud. Click here for further details, full credits, and larger versions of the image. Credit: ESA/Gaia/DPAC

One of the nearest galaxies to our Galaxy is the Large Magellanic Cloud (LMC), located around 166 000 light-years away and visible to the naked eye at intermediate and southern latitudes.

With a mass roughly equivalent to ten billion times the mass of our Sun – about one tenth of the Milky Way – the LMC is home to an intense star-forming activity, forming stars five time faster than in our Galaxy. Different aspects of the galaxy's stellar population are depicted in these two images, based on data collected by the Gaia satellite during its first 14 months of operations.

The view on the left, compiled by mapping the total density of stars detected by Gaia in each pixel of the image, shows the large-scale distribution of stars in the LMC, delineating the extent of the spiral arms. The image is peppered with bright dots – these are faint clusters of stars.

A series of diagonal stripes, visible along the central thick structure, or bar, are an artefact caused by Gaia's scanning procedure. These will gradually decrease as more data are gathered throughout the lifetime of the mission.

On the right, a different image provides a complementary view that reveals other aspects of this galaxy and its stars. Created by mapping the total amount of radiation, or flux, recorded per pixel by Gaia, this image is dominated by the brightest, most massive stars, which greatly outshine their fainter, lower-mass counterparts. In this view, the bar of the LMC is more clearly delineated, alongside individual regions of star formation like the sparkling 30 Doradus, visible just above the centre of the galaxy.

The images below, also obtained using data from the first 14 months of Gaia science operations, depict two nearby spiral galaxies: Andromeda (also known as M31), which is slightly more massive than the Milky Way and, at roughly 2.5 million light-years away, the largest galaxy in our vicinity; and its neighbour, the Triangulum galaxy (also known as M33) home to some fifty billion stars and located about 2.8 million light-years away.
Gaia's view of the Andromeda galaxy. Click here for further details, full credits, and larger versions of the image. Credit: ESA/Gaia/DPAC

As in the case of the LMC, the image on the left is based on the total density of stars, and shows where stars of all types are located, while the image on the right is based on the flux and mainly depicts the bright end of the stellar population of each galaxy, tracing out the regions of most intense star formation.
Gaia's view of the Triangulum galaxy. Click here for further details, full credits, and larger versions of the image. Credit: ESA/Gaia/DPAC

The first batch of Gaia data, released in 2016 and based on 14 months of science operations, contained the position and brightness of more than one billion stars. Most of these stars are located in the Milky Way, but a good fraction are extragalactic, with around ten million belonging to the LMC.

For all these stars and more, the second release of Gaia data – planned for April 2018 – will also contain measurements of their parallax, which quantifies a star's distance from us, and of their motion across the sky. Astronomers are eagerly awaiting this unprecedented data set to delve into the present and past mysteries of our Galaxy and its neighbours.

By analysing the motions of individual stars in external galaxies like the LMC, Andromeda, or Triangulum, it will be possible to learn more about the overall rotation of stars within these galaxies, as well as the orbit of the galaxies themselves in the swarm they are part of, known as the Local Group.

In the case of the LMC, a team of astronomers have already attempted to do so by using a subset of data from the first Gaia release, the Tycho–Gaia Astrometric Solution (TGAS), for which parallaxes and proper motions had also been provided by combining the new data with those from ESA's first astrometry mission, Hipparcos. In the TGAS data set, consisting of two million stars, they identified 29 stars in the LMC with good measurements of proper motions and used them to estimate the rotation of the galaxy, providing a taster of the studies that will become possible with future releases of Gaia data.

Observations of the LMC and its neighbour, the Small Magellanic Cloud (SMC), with Gaia are extremely important also for studying variable stars like Cepheids and RR Lyrae. These stars can be used as indicators of cosmic distances in galaxies beyond our own as long as they are first calibrated in a 'local' laboratory, such as the LMC and SMC, where it is possible to obtain a more direct estimate of their distance using parallax determined with Gaia.

Astronomers in the Gaia Data Processing and Analysis Consortium, or DPAC, tested this method on hundreds of LMC variable stars from the TGAS sample as part of the validation of the data from the first release. Their results, which are promising even though preliminary, are an exciting example of the rich scientific harvest that will be possible with future releases of the data that are being gathered by Gaia.

Last Update: 13 December 2017

Revenir en haut Aller en bas
Voir le profil de l'utilisateur http://www.atelier-yannistignard.com
yanis la chouette

Nombre de messages : 9682
Localisation : http://yanis.tignard.free.fr/
Date d'inscription : 09/11/2005


Marie worked as a secretary and science writer to her spouse and served as his amanuensis. She was his active assistant in his scientific experiments. She worked with him on expanding his first researches, around 1848, on the remarks previously made by Mitscherlich on the different optical properties concerning polarized light of tartaric acid when it came from natural wines, wine lees and when it was synthesized in a laboratory.

Mitscherlich is a Germanic surname which may refer to:

Alexander Mitscherlich (chemist) (1836–1918), a German chemist
Alexander Mitscherlich (psychologist) (1908–1982), a German psychiatrist
Andrea Ehrig-Mitscherlich (born 1 December 1960), a former German speed skater
Christoph Wilhelm Mitscherlich (1760–1854), a German classical scholar
Eilhard Mitscherlich (1794–1863), a German chemist
Margarete Mitscherlich-Nielsen (1917–2012), psychoanalyst
Thomas Mitscherlich (1942–1998), a German film director and screenwriter

Polarization (also polarisation) is a property applying to transverse waves that specifies the geometrical orientation of the oscillations.[1][2][3][4][5] In a transverse wave, the direction of the oscillation is transverse to the direction of motion of the wave, so the oscillations can have different directions perpendicular to the wave direction.[4] A simple example of a polarized transverse wave is vibrations traveling along a taut string (see image); for example, in a musical instrument like a guitar string. Depending on how the string is plucked, the vibrations can be in a vertical direction, horizontal direction, or at any angle perpendicular to the string. In contrast, in longitudinal waves, such as sound waves in a liquid or gas, the displacement of the particles in the oscillation is always in the direction of propagation, so these waves do not exhibit polarization. Transverse waves that exhibit polarization include electromagnetic waves such as light and radio waves, gravitational waves,[6] and transverse sound waves (shear waves) in solids. In some types of transverse waves, the wave displacement is limited to a single direction, so these also do not exhibit polarization; for example, in surface waves in liquids (gravity waves), the wave displacement of the particles is always in a vertical plane.

An electromagnetic wave such as light consists of a coupled oscillating electric field and magnetic field which are always perpendicular; by convention, the "polarization" of electromagnetic waves refers to the direction of the electric field. In linear polarization, the fields oscillate in a single direction. In circular or elliptical polarization, the fields rotate at a constant rate in a plane as the wave travels. The rotation can have two possible directions; if the fields rotate in a right hand sense with respect to the direction of wave travel, it is called right circular polarization, or, if the fields rotate in a left hand sense, it is called left circular polarization.

Light or other electromagnetic radiation from many sources, such as the sun, flames, and incandescent lamps, consists of short wave trains with an equal mixture of polarizations; this is called unpolarized light. Polarized light can be produced by passing unpolarized light through a polarizing filter, which allows waves of only one polarization to pass through. The most common optical materials (such as glass) are isotropic and do not affect the polarization of light passing through them; however, some materials—those that exhibit birefringence, dichroism, or optical activity—can change the polarization of light. Some of these are used to make polarizing filters. Light is also partially polarized when it reflects from a surface.

According to quantum mechanics, electromagnetic waves can also be viewed as streams of particles called photons. When viewed in this way, the polarization of an electromagnetic wave is determined by a quantum mechanical property of photons called their spin. A photon has one of two possible spins: it can either spin in a right hand sense or a left hand sense about its direction of travel. Circularly polarized electromagnetic waves are composed of photons with only one type of spin, either right- or left-hand. Linearly polarized waves consist of equal numbers of right and left hand spinning photons, with their phase synchronized so they superpose to give oscillation in a plane.

Polarization is an important parameter in areas of science dealing with transverse waves, such as optics, seismology, radio, and microwaves. Especially impacted are technologies such as lasers, wireless and optical fiber telecommunications, and radar.


Tartaric acid is a white crystalline organic acid that occurs naturally in many plants, most notably in grapes. Its salt, potassium bitartrate, commonly known as cream of tartar, develops naturally in the process of winemaking. It is commonly mixed with sodium bicarbonate and is sold as baking powder used as a leavening agent in food preparation. The acid itself is added to foods as an antioxidant and to impart its distinctive sour taste.

Tartaric is an alpha-hydroxy-carboxylic acid, is diprotic and aldaric in acid characteristics, and is a dihydroxyl derivative of succinic acid.


Tartaric acid was first isolated from potassium bitartrate circa 800 AD, by the alchemist Jābir ibn Hayyān.[4] The modern process was developed in 1769 by the Swedish chemist Carl Wilhelm Scheele.[5]

Tartaric acid played an important role in the discovery of chemical chirality. This property of tartaric acid was first observed in 1832 by Jean Baptiste Biot, who observed its ability to rotate polarized light.[6][7] Louis Pasteur continued this research in 1847 by investigating the shapes of sodium ammonium tartrate crystals, which he found to be chiral. By manually sorting the differently shaped crystals, Pasteur was the first to produce a pure sample of levotartaric acid.[8][9][10][11][12]
Tartaric acid crystals drawn as if seen through an optical microscope

Naturally occurring tartaric acid is chiral, and is a useful raw material in organic chemical synthesis. The naturally occurring form of the acid is dextrotartaric acid or D-(-)-tartaric acid. Because it is available naturally, it is slightly cheaper than its enantiomer and the meso isomer. The dextro and levo prefixes are archaic terms.[13] Modern textbooks refer to the natural form as 2S,3S-tartaric acid, and its enantiomer as 2R,3R-tartaric acid. The meso diastereomer is 2S,3R-tartaric acid, which is equivalent to 2R,3S-tartaric acid.

Whereas the two chiral stereoisomers rotate plane polarized light in opposite directions, solutions of meso-tartaric acid do not rotate plane-polarized light. The absence of optical activity is due to a mirror plane in the molecule [segmented line in picture below].[14][15]

Tartaric acid in Fehling's solution binds to copper(II) ions, preventing the formation of insoluble hydroxide salts.
dextrotartaric acid
(L-(+)-tartaric acid) levotartaric acid
(D-(-)-tartaric acid) mesotartaric acid

L-tartaric acid.png
D-tartaric acid.png Meso-Weinsäure Spiegel.svg

DL-tartaric acid (racemic acid)
(when in 1:1 ratio)
Forms of tartaric acid Common name Tartaric acid Levo-tartaric acid Dextro-tartaric acid Meso-tartaric acid Racemic acid
Synonyms D-(S,S)-(−)-tartaric acid
unnatural isomer[16] L-(R,R)-(+)-tartaric acid
natural isomer[17] (2R,3S)-tartaric acid DL-(S,S/R,R)-(±)-tartaric acid
PubChem CID 875 from PubChem CID 439655 from PubChem CID 444305 from PubChem CID 78956 from PubChem CID 5851 from PubChem
EINECS number 205-695-6 201-766-0 205-696-1 205-105-7
CAS number 526-83-0 147-71-7 87-69-4 147-73-9 133-37-9
L-(+)-Tartaric acid

The L-(+)-tartaric acid isomer of tartaric acid is industrially produced in the largest amounts. It is obtained from lees, a solid byproduct of fermentations. The former byproducts mostly consist of potassium bitartrate (KHC4H4O6). This potassium salt is converted to calcium tartrate (CaC4H4O6) upon treatment with milk of lime (Ca(OH)2):[18]


In practice, higher yields of calcium tartrate are obtained with the addition of calcium chloride. Calcium tartrate is then converted to tartaric acid by treating the salt with aqueous sulfuric acid:


Racemic tartaric acid

Racemic tartaric acid (i.e.: a 50:50 mixture of D-(-)-tartaric acid and L-(+)-tartaric acid molecules) can be prepared in a multistep reaction from maleic acid. In the first step, the maleic acid is epoxidized by hydrogen peroxide using potassium tungstate as a catalyst.[18]

HO2CC2H2CO2H + H2O2 → OC2H2(CO2H) 2

In the next step, the epoxide is hydrolyzed.

OC2H2(CO2H)2 + H2O → (HOCH)2(CO2H)2

meso-Tartaric acid

meso-Tartaric acid is formed via thermal isomerization. dextro-Tartaric acid is heated in water at 165 °C for about 2 days. meso-Tartaric acid can also be prepared from dibromosuccinic acid using silver hydroxide:[19]


meso-Tartaric acid can be separated from residual racemic acid by crystallization, the racemate being less soluble.

L-(+)-tartaric acid, can participate in several reactions. As shown the reaction scheme below, dihydroxymaleic acid is produced upon treatment of L-(+)-tartaric acid with hydrogen peroxide in the presence of a ferrous salt.


Dihydroxymaleic acid can then be oxidized to tartronic acid with nitric acid.[20]
Tartar emetic
Commercially produced tartaric acid

Important derivatives of tartaric acid include its salts, cream of tartar (potassium bitartrate), Rochelle salt (potassium sodium tartrate, a mild laxative), and tartar emetic (antimony potassium tartrate).[21][22][23] Diisopropyl tartrate is used as a catalyst in asymmetric synthesis.

Tartaric acid is a muscle toxin, which works by inhibiting the production of malic acid, and in high doses causes paralysis and death.[24] The median lethal dose (LD50) is about 7.5 grams/kg for a human, 5.3 grams/kg for rabbits, and 4.4 grams/kg for mice.[25] Given this figure, it would take over 500 g (18 oz) to kill a person weighing 70 kg (150 lb), so it may be safely included in many foods, especially sour-tasting sweets. As a food additive, tartaric acid is used as an antioxidant with E number E334; tartrates are other additives serving as antioxidants or emulsifiers.

When cream of tartar is added to water, a suspension results which serves to clean copper coins very well, as the tartrate solution can dissolve the layer of copper(II) oxide present on the surface of the coin. The resulting copper(II)-tartrate complex is easily soluble in water.
Tartaric acid in wine
See also: Acids in wine and Tartrate
Unpurified potassium bitartrate can take on the color of the grape juice from which it was separated.

Tartaric acid may be most immediately recognizable to wine drinkers as the source of "wine diamonds", the small potassium bitartrate crystals that sometimes form spontaneously on the cork or bottom of the bottle. These "tartrates" are harmless, despite sometimes being mistaken for broken glass, and are prevented in many wines through cold stabilization (which is not always preferred since it can change the wine's profile). The tartrates remaining on the inside of aging barrels were at one time a major industrial source of potassium bitartrate.

Tartaric acid plays an important role chemically, lowering the pH of fermenting "must" to a level where many undesirable spoilage bacteria cannot live, and acting as a preservative after fermentation. In the mouth, tartaric acid provides some of the tartness in the wine, although citric and malic acids also play a role.

Tartaric acid and its derivatives have a plethora of uses in the field of pharmaceuticals. For example, it has been used in the production of effervescent salts, in combination with citric acid, to improve the taste of oral medications.[20] The potassium antimonyl derivative of the acid known as tartar emetic is included, in small doses, in cough syrup as an expectorant.

Tartaric acid also has several applications for industrial use. The acid has been observed to chelate metal ions such as calcium and magnesium. Therefore, the acid has served in the farming and metal industries as a chelating agent for complexing micronutrients in soil fertilizer and for cleaning metal surfaces consisting of aluminium, copper, iron, and alloys of these metals, respectively.[18]

Tartaric Acid – Compound Summary, PubChem.
Dawson, R.M.C. et al., Data for Biochemical Research, Oxford, Clarendon Press, 1959.
Lide, D. R., ed. (2005). CRC Handbook of Chemistry and Physics (86th ed.). Boca Raton (FL): CRC Press. ISBN 0-8493-0486-5.
Lisa Solieri, Paolo Giudici (2009). Vinegars of the World. Springer. p. 29. ISBN 88-470-0865-4.
Retzius, Anders Jahan (1770) "Försök med vinsten och dess syra" (Experiments with cream of tartar and its acid), Kungliga Vetenskapsakademiens Handlingar (Proceedings of the Royal Academy of Sciences), 31 : 207–213. From p. 209: "§. 6. Dessa försök omtalte jag för Hr. Carl Wilhelm Scheele (en snabb och lårgirug Pharmaciæ Studiosus) … " (§. 6. I mention these experiments on behalf of Mr. Carl Wilhelm Scheele (a quick and studious student of pharmacology) … )
Biot (1835) "Mémoire sur la polarization circulaire et sur ses applications à la chimie organique" (Memoir on circular polarization and on its applications to organic chemistry), Mémoires de l'Académie des sciences de l'Institut, 2nd series, 13 : 39–175. That tartaric acid (acide tartarique cristallisé) rotates plane-polarized light is shown in Table G following p. 168. (Note: This article was read to the French Royal Academy of Sciences on 1832 November 5.)
Biot (1838) "Pour discerner les mélanges et les combinaisons chimiques définies ou non définies, qui agissent sur la lumière polarisée; suivies d'applications aux combinaisons de l'acide tartarique avec l'eau, l'alcool et l'esprit de bois" (In order to discern mixtures and chemical combinations, defined or undefined, which act on polarized light; followed by applications to combinations of tartaric acid with water, alcohol [i.e., ethanol], and spirit of wood [i.e., methanol]), Mémoires de l'Académie des sciences de l'Institut, 2nd series, 15 : 93–279.
L. Pasteur (1848) "Mémoire sur la relation qui peut exister entre la forme cristalline et la composition chimique, et sur la cause de la polarisation rotatoire" (Memoir on the relationship which can exist between crystalline form and chemical composition, and on the cause of rotary polarization)," Comptes rendus de l'Académie des sciences (Paris), 26 : 535–538.
L. Pasteur (1848) "Sur les relations qui peuvent exister entre la forme cristalline, la composition chimique et le sens de la polarisation rotatoire" (On the relations that can exist between crystalline form, and chemical composition, and the sense of rotary polarization), Annales de Chimie et de Physique, 3rd series, 24 : 442–459.
Pasteur, Louis (1850) "Recherches sur les propriétés spécifiques des deux acides qui composent l'acide racémique" (Investigations into the specific properties of the two acids that compose racemic acid), Annales de Chimie et de Physique, 3rd series, 28 (3) : 56–99. See also Plate II. (See also the report of the commission that was appointed to verify Pasteur's findings, pp. 99–117.) [in French]
George B. Kauffman and Robin D. Myers (1998). "Pasteur's resolution of racemic acid: A sesquicentennial retrospect and a new translation" (PDF). The Chemical Educator. 3 (6): 1–4. doi:10.1007/s00897980257a.
H. D. Flack (2009). "Louis Pasteur's discovery of molecular chirality and spontaneous resolution in 1848, together with a complete review of his crystallographic and chemical work" (PDF). Acta Crystallographica A. 65 (5): 371–389. doi:10.1107/S0108767309024088. PMID 19687573.
J. M. McBride's Yale lecture on history of stereochemistry of tartaric acid, the D/L and R/S systems
various (2007-07-23). Organic Chemistry. Global Media. p. 65. ISBN 978-81-89940-76-8. Retrieved 2010-06-05.
"(WO/2008/022994) Use of azabicyclo hexane derivatives".
https://pubchem.ncbi.nlm.nih.gov/compound/439655. Missing or empty |title= (help)
https://pubchem.ncbi.nlm.nih.gov/compound/L-tartaric_acid. Missing or empty |title= (help)
J.-M. Kassaian "Tartaric acid" in Ullmann's Encyclopedia of Industrial Chemistry; VCH: Weinheim, Germany, 2002, 35, 671-678. doi:10.1002/14356007.a26_163
Augustus Price West. Experimental Organic Chemistry. World Book Company: New York, 1920, 232-237.
Blair, G. T.; DeFraties, J. J. (2000). "Hydroxy Dicarboxylic Acids". Kirk Othmer Encyclopedia of Chemical Technology. pp. 1–19. doi:10.1002/0471238961.0825041802120109.a01.
Zalkin, Allan; Templeton, David H.; Ueki, Tatzuo (1973). "Crystal structure of l-tris(1,10-phenathroline)iron(II) bis(antimony(III) d-tartrate) octahydrate". Inorganic Chemistry. 12 (7): 1641–1646. doi:10.1021/ic50125a033.
Haq, I; Khan, C (1982). "Hazards of a traditional eye-cosmetic--SURMA". JPMA. the Journal of the Pakistan Medical Association. 32 (1): 7–8. PMID 6804665.
McCallum, RI (1977). "President's address. Observations upon antimony". Proceedings of the Royal Society of Medicine. 70 (11): 756–63. PMC 1543508 Freely accessible. PMID 341167.
Alfred Swaine Taylor, Edward Hartshorne (1861). Medical jurisprudence. Blanchard and Lea. p. 61.

Joseph A. Maga, Anthony T. Tu (1995). Food additive toxicology. CRC Press. pp. 137–138. ISBN 0-8247-9245-9.

External links
Wikimedia Commons has media related to Tartaric acid.

PDB file for MSE


News | December 13, 2017
Sierras Lost Water Weight, Grew Taller During Drought

Loss of water from the rocks of California's Sierra Nevada caused the mountain range to rise nearly an inch (24 millimeters) in height during the drought years from October 2011 to October 2015, a new NASA study finds. In the two following years of more abundant snow and rainfall, the mountains have regained about half as much water in the rock as they had lost in the preceding drought and have fallen about half an inch (12 millimeters) in height.

"This suggests that the solid Earth has a greater capacity to store water than previously thought," said research scientist Donald Argus of NASA's Jet Propulsion Laboratory in Pasadena, California, who led the study. Significantly more water was lost from cracks and soil within fractured mountain rock during drought and gained during heavy precipitation than hydrology models show.

Argus is giving a talk on the new finding today at the American Geophysical Union's fall conference in New Orleans.

The research team used advanced data-processing techniques on data from 1,300 GPS stations in the mountains of California, Oregon and Washington, collected from 2006 through October 2017. These research-quality GPS receivers were installed as part of the National Science Foundation's Plate Boundary Observatory to measure subtle tectonic motion in the region's active faults and volcanoes. They can monitor elevation changes within less than a tenth of an inch (a few millimeters).

The team found that the amount of water lost from within fractured mountain rock in 2011-2015 amounted to 10.8 cubic miles of water. This water is too inaccessible to be used for human purposes, but for comparison, the amount is 45 times as much water as Los Angeles currently uses in a year.

JPL water scientist Jay Famiglietti, who collaborated on the research, said the finding solves a mystery for hydrologists. "One of the major unknowns in mountain hydrology is what happens below the soil. How much snowmelt percolates through fractured rock straight downward into the core of the mountain? This is one of the key topics that we addressed in our study."

Earth's surface falls locally when it is weighed down with water and rebounds when the weight disappears. Many other factors also change the ground level, such as the movement of tectonic plates, volcanic activity, high- and low-pressure weather systems, and Earth's slow rebound from the last ice age. The team corrected for these and other factors to estimate how much of the height increase was solely due to water loss from rock.

Before this study, scientists' leading theories for the growth of the Sierra were tectonic uplift or Earth rebounding from extensive groundwater pumping in the adjoining California Central Valley. Argus calculated that these two processes together only produced a quarter of an inch (7 millimeters) of growth -- less than a third of the total.

Famiglietti said the techniques developed for this study will allow scientists to begin exploring other questions about mountain groundwater. "What does the water table look like within mountain ranges? Is there a significant amount of groundwater stored within mountains? We just don't have answers yet, and this study identities a set of new tools to help us get them."

A paper on the research, titled "Sustained water loss in California's mountain ranges during severe drought from 2012 through 2015 inferred from GPS," was published in the Journal of Geophysical Research: Solid Earth.

News Media Contact
Alan Buis
Jet Propulsion Laboratory, Pasadena, California

Written by Carol Rasmussen
NASA's Earth Science News Team




VITA mission 'Timelapse a Day' edition - from California to Mexico - YouTube


Revenir en haut Aller en bas
Voir le profil de l'utilisateur http://www.atelier-yannistignard.com
yanis la chouette

Nombre de messages : 9682
Localisation : http://yanis.tignard.free.fr/
Date d'inscription : 09/11/2005


News | December 13, 2017
Mars Mission Sheds Light on Habitability of Distant Planets.

How long might a rocky, Mars-like planet be habitable if it were orbiting a red dwarf star? It's a complex question but one that NASA's Mars Atmosphere and Volatile Evolution mission can help answer.

"The MAVEN mission tells us that Mars lost substantial amounts of its atmosphere over time, changing the planet's habitability," said David Brain, a MAVEN co-investigator and a professor at the Laboratory for Atmospheric and Space Physics at the University of Colorado Boulder. "We can use Mars, a planet that we know a lot about, as a laboratory for studying rocky planets outside our solar system, which we don't know much about yet."

At the fall meeting of the American Geophysical Union on Dec. 13, 2017, in New Orleans, Louisiana, Brain described how insights from the MAVEN mission could be applied to the habitability of rocky planets orbiting other stars.

MAVEN carries a suite of instruments that have been measuring Mars' atmospheric loss since November 2014. The studies indicate that Mars has lost the majority of its atmosphere to space over time through a combination of chemical and physical processes. The spacecraft's instruments were chosen to determine how much each process contributes to the total escape.

In the past three years, the Sun has gone through periods of higher and lower solar activity, and Mars also has experienced solar storms, solar flares and coronal mass ejections. These varying conditions have given MAVEN the opportunity to observe Mars' atmospheric escape getting cranked up and dialed down.

Brain and his colleagues started to think about applying these insights to a hypothetical Mars-like planet in orbit around some type of M-star, or red dwarf, the most common class of stars in our galaxy.

The researchers did some preliminary calculations based on the MAVEN data. As with Mars, they assumed that this planet might be positioned at the edge of the habitable zone of its star. But because a red dwarf is dimmer overall than our Sun, a planet in the habitable zone would have to orbit much closer to its star than Mercury is to the Sun.

The brightness of a red dwarf at extreme ultraviolet (UV) wavelengths combined with the close orbit would mean that the hypothetical planet would get hit with about 5 to 10 times more UV radiation than the real Mars does. That cranks up the amount of energy available to fuel the processes responsible for atmospheric escape. Based on what MAVEN has learned, Brain and colleagues estimated how the individual escape processes would respond to having the UV cranked up.

Their calculations indicate that the planet's atmosphere could lose 3 to 5 times as many charged particles, a process called ion escape. About 5 to 10 times more neutral particles could be lost through a process called photochemical escape, which happens when UV radiation breaks apart molecules in the upper atmosphere.

Because more charged particles would be created, there also would be more sputtering, another form of atmospheric loss. Sputtering happens when energetic particles are accelerated into the atmosphere and knock molecules around, kicking some of them out into space and sending others crashing into their neighbors, the way a cue ball does in a game of pool.

Finally, the hypothetical planet might experience about the same amount of thermal escape, also called Jeans escape. Thermal escape occurs only for lighter molecules, such as hydrogen. Mars loses its hydrogen by thermal escape at the top of the atmosphere. On the exo-Mars, thermal escape would increase only if the increase in UV radiation were to push more hydrogen to the top of the atmosphere.

Altogether, the estimates suggest that orbiting at the edge of the habitable zone of a quiet M-class star, instead of our Sun, could shorten the habitable period for the planet by a factor of about 5 to 20. For an M-star whose activity is amped up like that of a Tasmanian devil, the habitable period could be cut by a factor of about 1,000 -- reducing it to a mere blink of an eye in geological terms. The solar storms alone could zap the planet with radiation bursts thousands of times more intense than the normal activity from our Sun.

However, Brain and his colleagues have considered a particularly challenging situation for habitability by placing Mars around an M-class star. A different planet might have some mitigating factors -- for example, active geological processes that replenish the atmosphere to a degree, a magnetic field to shield the atmosphere from stripping by the stellar wind, or a larger size that gives more gravity to hold on to the atmosphere.

"Habitability is one of the biggest topics in astronomy, and these estimates demonstrate one way to leverage what we know about Mars and the Sun to help determine the factors that control whether planets in other systems might be suitable for life," said Bruce Jakosky, MAVEN's principal investigator at the University of Colorado Boulder.

MAVEN's principal investigator is based at the University of Colorado's Laboratory for Atmospheric and Space Physics, Boulder. The university provided two science instruments and leads science operations, as well as education and public outreach, for the mission. NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the MAVEN project and provided two science instruments for the mission. NASA's Jet Propulsion Laboratory, a division of Caltech in Pasadena, California, manages the Mars Exploration Program for NASA's Science Mission Directorate, Washington.

For more information about MAVEN, visit:

Their eldest daughter, Jeanne, died from typhoid fever, aged 9, at Arbois. Then, in 1865, 2-year-old Camille also died of typhus, followed by 12-and-a-half-year-old Cécile on 23 May 1866. Only Jean Baptiste and Marie Louise lived to be adults. Jean Baptiste would be a soldier in the Franco-Prussian War between France and Prussia.

News Media Contact
Laurie Cantillo / Dwayne Brown
NASA Headquarters, Washington
202-358-1077 / 202-358-1726
laura.l.cantillo@nasa.gov / dwayne.c.brown@nasa.gov

Written by Elizabeth Zubritsky
NASA's Goddard Space Flight Center, Greenbelt, Md.



Related Story: Spanning Disciplines in the Search for Life Beyond Earth

Following a gold rush of exoplanet discovery, the next step in the search for life is determining which of the known exoplanets are proper candidates for life — and for this, a cross-disciplinary approach is essential.

Dec. 13, 2017
Spanning Disciplines in the Search for Life Beyond Earth

Related story: Mars Mission Sheds Light on Habitability of Distant Planets

Insights from NASA's Mars Atmosphere and Volatile Evolution, or MAVEN, mission about the loss of the Red Planet's atmosphere can help scientists understand the habitability of rocky planets orbiting other stars.

Download related briefing materials from Dec. 13’s press conference at the 2017 American Geophysical Union meeting.

The search for life beyond Earth is riding a surge of creativity and innovation. Following a gold rush of exoplanet discovery over the past two decades, it is time to tackle the next step: determining which of the known exoplanets are proper candidates for life.

Scientists from NASA and two universities presented new results dedicated to this task in fields spanning astrophysics, Earth science, heliophysics and planetary science — demonstrating how a cross-disciplinary approach is essential to finding life on other worlds — at the fall meeting of the American Geophysical Union on Dec. 13, 2017, in New Orleans, Louisiana.

“The potentially habitable real estate in the universe has greatly expanded,” said Giada Arney, an astrobiologist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “We now know of thousands of exoplanets, but what we know about them is limited because we can’t yet see them directly.”

Currently, scientists mostly rely on indirect methods to identify and study exoplanets; such methods can tell them whether a planet is Earth-like or how close it is to its parent star. But this isn’t yet enough to say whether a planet is truly habitable, or suitable for life — for this, scientists must ultimately be able to observe exoplanets directly.

Direct-imaging instrument and mission designs are underway, but in the meantime, Arney explained, scientists are making progress with tools already at their disposal. They are building computational models to simulate what habitable planets might look like and how they would interact with their parent stars. To validate their models, they are looking to planets within our own solar system, as analogs for the exoplanets we may one day discover. This, of course, includes Earth itself — the planet we know best, and the only one we know of yet that is habitable.

“In our quest for life on other worlds, it is important for scientists to consider exoplanets from a holistic sense — that is, from the perspective of multiple disciplines,” Arney said. “We need these multi-disciplinary studies to examine exoplanets as the complex worlds shaped by multiple astrophysical, planetary and stellar processes, rather than just distant points in the sky.”

Studying Earth as an Exoplanet

When humans start collecting the first direct images of exoplanets, even the closest image will appear as a handful of pixels. What can we learn about planetary life from just a smattering of pixels?

Stephen Kane, an exoplanets expert at the University of California, Riverside, has come up with one way to answer that question using NASA’s Earth Polychromatic Imaging Camera aboard the National Oceanic and Atmospheric Administration’s Deep Space Climate Observatory, or DSCOVR. Kane explained that he and his colleagues take DSCOVR’s high-resolution images — typically used to document Earth’s global weather patterns and other climate-related events — and degrade them down to images just a few pixels in size. Kane runs the DSCOVR images through a noise filter that attempts to simulate the interference expected from an exoplanet mission.

“From just a handful of pixels, we try to extract as much information that we know about Earth as we can,” Kane said. “If we can do it accurately for Earth, we can do this for planets around other stars.”
Image of Earth and future exoplanet observations
Left, an image of Earth from the DSCOVR-EPIC camera. Right, the same image degraded to a resolution of 3-by-3 pixels, similar to what researchers will see in future exoplanet observations.

DSCOVR takes a picture every half hour and it's been in orbit for two years. Its more than 30,000 images are by far the longest continuous record of full-disk observations from space in existence. By observing how the brightness of Earth changes when mostly land is in view compared with mostly water, Kane has been able to reverse-engineer Earth's albedo, obliquity, rotation rate and even seasonal variation — something that has yet to be measured directly for exoplanets — all of which could potentially influence a planet’s ability to support life.
Searching for Other Venuses

Much the way scientists use Earth as a case-study for habitable planets, they also use planets within the solar system — and therefore planets they are more familiar with — as studies for what makes planets uninhabitable.

Kane also studies Earth’s sister planet, Venus, where the surface is 850 degrees Fahrenheit and the atmosphere — filled with sulfuric acid — bogs down on the surface with 90 times the pressure of Earth’s. Since Earth and Venus are so close in size and yet so different in terms of their prospects for habitability, he is interested in developing methods for distinguishing Earth- and Venus-analogs in other planetary systems, as a way of identifying potentially habitable terrestrial planets.

Kane explained that he works to identify Venus analogs in data from NASA’s Kepler by defining the “Venus Zone,” where planetary insolation — how much light a given planet receives from its host star — plays a key role in atmospheric erosion and greenhouse gas cycles.

“The fate of Earth and Venus and their atmospheres are tied to each other,” Kane said. “By searching for similar planets, we are trying to understand their evolution, and ultimately how often developing planets end up a Venus-like hellscape.”
Since Earth, right, and Venus, left, are so close in size and yet so different in terms of their prospects for habitability, Stephen Kane, an exoplanets expert at the University of California, Riverside, is interested in developing methods for distinguishing Earth- and Venus-analogs in other planetary systems, as a way of identifying potentially habitable terrestrial planets.
Credits: NASA/JPL-Caltech/Ames

Modeling Star-Planet Interactions

While Kane talked about planets, Goddard space scientist Katherine Garcia-Sage focused on the way planets interact with their host star. Scientists must also consider how the qualities of a host star and a planet’s electromagnetic environment — which can shield it from harsh stellar radiation — either hinder or help habitability. Earth’s magnetic field, for example, protects the atmosphere from the harsh solar wind, the Sun’s constant outpouring of charged solar material, which can strip away atmospheric gases in a process called ionospheric escape.

Garcia-Sage described research on Proxima b, an exoplanet that is four light-years away and known to exist within the habitable zone of its red dwarf star, Proxima Centauri. But just because it’s in the habitable zone — the right distance from a star where water could pool on a planet’s surface — doesn’t necessarily mean it’s habitable.

While scientists can’t yet tell whether Proxima b is magnetized, they can use computational models to simulate how well an Earth-like magnetic field would protect its atmosphere at the exoplanet’s close orbit to Proxima Centauri, which frequently produces violent stellar storms. The effects of such storms on a given planet’s space environment are collectively known as space weather.

“We need to understand a planet’s space weather environment to understand whether a planet is habitable,” Garcia-Sage said. “If the star is too active, it can endanger an atmosphere, which is necessary for providing liquid water. But there’s a fine line: There is some indication that radiation from a star can produce building blocks for life.”

A red dwarf star — one of the most common types of stars in our galaxy — like Proxima Centauri strips away atmosphere when extreme ultraviolet radiation ionizes atmospheric gases, producing a swath of electrically charged particles that can stream out into space along magnetic field lines.
illustration of ion escape from exoplanet atmosphere
In this illustration, extreme ultraviolet light from an active red dwarf star cause ions to escape from an exoplanet’s atmosphere.
Credits: NASA's Goddard Space Flight Center

The scientists calculated how much radiation Proxima Centauri produces on average, based on observations from NASA’s Chandra X-ray Observatory. At Proxima b’s orbit, the scientists found their Earth-like planet encountered bouts of extreme ultraviolet radiation hundreds of times greater than Earth does from the Sun.

Garcia-Sage and her colleagues designed a computer model to study whether an Earth-like planet — with Earth’s atmosphere, magnetic field and gravity — in Proxima b’s orbit could hold on to its atmosphere. They examined three factors that drive ionospheric escape: stellar radiation, temperature of the neutral atmosphere, and size of the polar cap, the region over which the escape happens.

The scientists show that with the extreme conditions likely to exist at Proxima b, the planet could lose an amount equivalent to the entirety of Earth’s atmosphere in 100 million years — just a fraction of Proxima b’s 4 billion years thus far. Even in the best-case scenario, that much mass escapes over 2 billion years, well within the planet’s lifetime.

Mars, a Laboratory for Studying Exoplanets

While Garcia-Sage spoke of magnetized planets, David Brain, planetary scientist at the University of Colorado, Boulder, spoke of Mars — a planet without a magnetic field.

“Mars is a great laboratory for thinking about exoplanets,” Brain said. “We can use Mars to help constrain our thinking about a variety of rocky exoplanets where we don’t have observations yet.”

Brain’s research uses observations from NASA’s Mars Atmosphere and Volatile Evolution, or MAVEN, mission to ask the question: How would Mars have evolved if it were orbiting a different kind of star? The answer provides information for how rocky planets — not unlike our own — could develop differently in different situations.

It is thought that Mars once carried water and an atmosphere that might have made it hospitable to Earth-like life. But Mars lost much of its atmosphere over time through a variety of chemical and physical processes — MAVEN has observed similar atmospheric loss on the planet since its launch in late 2013.

Brain, a MAVEN co-investigator, and his colleagues applied MAVEN’s insights to a hypothetical simulation of a Mars-like planet orbiting an M-class star — commonly known as a red dwarf star. In this imaginary situation, the planet would receive about five to 10 times more ultraviolet radiation than the real Mars does, which in turn speeds up atmospheric escape to much higher rates. Their calculations indicate that the planet’s atmosphere could lose three to five times as many charged particles and about five to 10 times more neutral particles.

Such a rate of atmospheric loss suggests that orbiting at the edge of the habitable zone of a quiet M-class star, instead of our Sun, could shorten the habitable period for the planet by a factor of about five to 20.
depiction of our solar system (bottom) and an M-type red dwarf solar system (top)
To receive the same amount of starlight as Mars receives from our Sun, a planet orbiting an M-type red dwarf would have to be positioned much closer to its star than Mercury is to the Sun.
Credits: NASA's Goddard Space Flight Center

“But I wouldn’t give up hope for rocky planets orbiting M dwarfs,” Brain said. “We picked a worst-case scenario. Mars is a small planet, and lacks a magnetic field so solar wind can more effectively strip away its atmosphere. We also picked a Mars that isn’t geologically active, so there’s no internal source of atmosphere. If you changed any one factor, such a planet might be a happier place.”

Each one of these studies contributes just one piece to a much larger puzzle — to determine what characteristics we should look for, and need to recognize, in the search for a planet that might support life. Together, such interdisciplinary research lays the groundwork to ensure that, as new missions to observe exoplanets more clearly are developed, we’ll be ready to determine if they might just host life.

Banner image: An illustration of Kepler-186f, the first Earth-size planet discovered within a star’s habitable zone. Scientists now know of thousands of exoplanets, but our knowledge is limited because we can’t yet view them directly. Credit: NASA Ames/SETI Institute/JPL-Caltech

By Lina Tran, Karen Fox, Elizabeth Zubritsky, Carol Rasmussen
NASA’s Goddard Space Flight Center, Greenbelt, Md.
Last Updated: Dec. 13, 2017
Editor: Rob Garner
Tags: Astrobiology, Earth, Exoplanets, Goddard Space Flight Center, Mars, Planets, Solar System, Space Weather, Sun, Universe



Revenir en haut Aller en bas
Voir le profil de l'utilisateur http://www.atelier-yannistignard.com
yanis la chouette

Nombre de messages : 9682
Localisation : http://yanis.tignard.free.fr/
Date d'inscription : 09/11/2005



The Biographical Dictionary of Women in Science: Pioneering Lives from Ancient Times to the Mid-20th Century (2 Vol. Set) by Marilyn Bailey OGILVIE (Editor), Joy Dorothy HARVEY(Editor), Taylor and Francis, Kindle Edition, (wireless edition), File Size: 2779 KB, Print Length: 1499 pages
The Biographical Dictionary of Women in Science: L-Z by Marilyn Bailey Ogilvie,Joy Dorothy Harvey

The Math of NASA Missions
Saturday, January 13, 9 a.m. to 12 p.m.
NASA Jet Propulsion Laboratory, Pasadena, California
Target Audience:
Teachers for grades 7-12

One of the recurring questions teachers get is, "When are we going to use this in real life?" In this session, we explore classroom lessons aligned to Common Core Math and Next Generation Science Standards (NGSS) that answer that question in exciting ways and get students engaged. We'll explore virtual reality, JPL missions and how space science can enrich the content in your class to get students excited about math.

This workshop is not available online; you must physically be present to participate
This workshop is limited to educators at U.S.-based institutions and organizations

› Register Online

Questions? Call the Educator Resource Center at 818-393-5917

Can't attend the workshop? Explore these standards-aligned activities on our website!

Lets Go to Mars (Grades 9-12) – This lesson has students use geometry to determine the distance travelled by a satellite as it moves from Earth to Mars.
Powering Through the Solar System with Exponents (Grades 6-Cool – How much light gets to distant planets? Learn how light and energy is distributed through space using math.

The Math of NASA Missions
Saturday, January 13, 9 a.m. to 12 p.m.
NASA Jet Propulsion Laboratory, Pasadena, California
Target Audience:
Teachers for grades 7-12

One of the recurring questions teachers get is, "When are we going to use this in real life?" In this session, we explore classroom lessons aligned to Common Core Math and Next Generation Science Standards (NGSS) that answer that question in exciting ways and get students engaged. We'll explore virtual reality, JPL missions and how space science can enrich the content in your class to get students excited about math.

This workshop is not available online; you must physically be present to participate
This workshop is limited to educators at U.S.-based institutions and organizations

› Register Online

Questions? Call the Educator Resource Center at 818-393-5917

Can't attend the workshop? Explore these standards-aligned activities on our website!

Lets Go to Mars (Grades 9-12) – This lesson has students use geometry to determine the distance travelled by a satellite as it moves from Earth to Mars.
Powering Through the Solar System with Exponents (Grades 6-Cool – How much light gets to distant planets? Learn how light and energy is distributed through space using math.

Revenir en haut Aller en bas
Voir le profil de l'utilisateur http://www.atelier-yannistignard.com
yanis la chouette

Nombre de messages : 9682
Localisation : http://yanis.tignard.free.fr/
Date d'inscription : 09/11/2005



At seems that for years afterward, famous crystallographer, physicist and mathematician Jean Baptiste Biot, Madame Marie Pasteur and Louis' father, Jean Joseph cooperated in providing Louis with moral support. For instance, in a letter by Biot to Louis father: "your son is ours also and we share with Marie all our love for him, too". There was also philosopher Charles Chappuis in this support network around Louis.

The search for life beyond Earth is riding a surge of creativity and innovation. Following a gold rush of exoplanet discovery over the past two decades, it is time to tackle the next step: determining which of the known exoplanets are proper candidates for life.

Scientists from NASA and two universities presented new results dedicated to this task in fields spanning astrophysics, Earth science, heliophysics and planetary science — demonstrating how a cross-disciplinary approach is essential to finding life on other worlds — at the fall meeting of the American Geophysical Union on Dec. 13, 2017, in New Orleans, Louisiana.

“The potentially habitable real estate in the universe has greatly expanded,” said Giada Arney, an astrobiologist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “We now know of thousands of exoplanets, but what we know about them is limited because we can’t yet see them directly.”
Bring the wonder of space to your students. Explore our universe of science, technology, engineering and math activities and resources.


News | December 13, 2017
Next-Generation GRACE Satellites Arrive at Launch Site

A pair of advanced U.S./German Earth research satellites with some very big shoes to fill is now at California's Vandenberg Air Force Base to begin final preparations for launch next spring.

Following a year-long test campaign by satellite manufacturer Airbus Defence and Space at IABG in Ottobrunn, near Munich, Germany, the twin Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) satellites were loaded aboard an air freighter at Munich airport Dec. 11 and arrived at the launch site on California's central coast Tuesday, Dec. 12. GRACE-FO will provide continuity to the Earth climate data record of the extremely successful predecessor GRACE, which completed its science mission in October after more than 15 years in orbit.

GRACE-FO will extend GRACE's legacy of scientific achievements, which range from tracking mass changes of Earth's polar ice sheets and estimating global groundwater changes, to measuring the mass changes of large earthquakes and inferring changes in deep ocean currents, a driving force in climate. To date, GRACE observations have been used in more than 4,300 research publications. Its measurements provide a unique view of the Earth system and have far-reaching benefits to society, such as providing insights into where global groundwater resources may be shrinking or growing and where dry soils are contributing to drought. GRACE-FO is planned to fly at least five years.

The GRACE-FO spacecraft will undergo final tests before being integrated atop a SpaceX Falcon 9 rocket, where they will share a ride to space with five Iridium NEXT communications satellites.

"With this milestone, we are now in position to launch GRACE Follow-On and restart the valuable observations and science that ceased in mid-2017 with the end of the GRACE science mission," said Michael Watkins, director of NASA's Jet Propulsion Laboratory in Pasadena, California, and GRACE Follow-On science team lead.

After a few months of in-orbit checkout, GRACE-FO will track changes in the distribution of liquid water, ice and land masses by measuring changes in Earth's gravity field every 30 days. GRACE-FO will essentially measure how much mass is gained or lost each month on the continents, in the oceans, and in the ice sheets. These data will improve scientific understanding of Earth system processes and the accuracy of environmental monitoring and forecasts.

The continuous movement of masses of water, ice, air and the solid Earth that GRACE-FO will track is driven by Earth system processes such as:

Terrestrial water cycle processes, such as precipitation, droughts, floods, changes in ice sheets and land glaciers, evaporation from the oceans, and groundwater use and storage.
Tectonic processes, such as earthquakes and variations in Earth's lithosphere (the rigid outer layer of our planet that includes the crust and upper mantle) and mantle density.

The GRACE-FO satellites will be launched into a polar orbit at an altitude of about 311 miles (500 kilometers). Flying 137 miles (220 kilometers) apart, the satellites will use a JPL-built microwave ranging system to take continuous, very precise measurements of the variations in the distance between each other. These variations are caused by minute changes in the gravitational pull on the satellites from local changes in Earth's mass below them. The microwave ranging data are combined with GPS tracking for timing, star trackers for attitude information, and an accelerometer built at ONERA in France to account for non-gravitational effects, such as atmospheric drag and solar radiation. From these data, scientists will calculate how mass is redistributed each month and monitor its changes over time.

Each satellite will also carry an instrument called an atmospheric limb sounder that will provide an innovative and cost-effective technique to measure how much signals from GPS satellites are distorted by the atmosphere. The sounders will provide up to 200 profiles of atmospheric temperature and water vapor content each day to aid weather forecasting.

While similar to their predecessor GRACE satellites, GRACE-FO incorporates design upgrades gleaned from 15 years of GRACE operations that will improve satellite performance, reliability and mission operations. GRACE-FO will also fly a new, more precise inter-satellite laser ranging instrument, developed by a German/American joint venture, which will be tested for use in future generations of GRACE-like missions.

GRACE-FO is a partnership between JPL and the German Research Centre for Geosciences (GFZ) in Potsdam, with participation by Deutsches Zentrum für Luft- und Raumfahrt (DLR), the German Aerospace Center.

For more information on GRACE-FO, visit:


News Media Contact
Alan Buis
Jet Propulsion Laboratory, Pasadena, California



Revenir en haut Aller en bas
Voir le profil de l'utilisateur http://www.atelier-yannistignard.com
yanis la chouette

Nombre de messages : 9682
Localisation : http://yanis.tignard.free.fr/
Date d'inscription : 09/11/2005


LIVE | Compte-rendu du #ConseildesMinistres du mercredi 13 décembre 2017 par @BGriveaux.

En réponse à @Elysee @justice_gouv @BGriveaux
AUGUST AMES, LA PAPESSE, LE DEUIL ET LA PRIÈRE. http://leclandesmouettes.bbflash.net/t642-august-ames-la-papesse-le-deuil-et-la-priere
Tarot divinatoire. https://fr.wikipedia.org/wiki/Tarot_divinatoire
Shield Theme. https://www.youtube.com/watch?v=jzWBjhaioKg

The Lamb Lies Down On Broadway - Genesis

les guignols-Mitterand et nanard.
“La chance ne s'explique pas.”
De Shirley Temple
"Mais, elle laisse des traces."
De La Vie.

Genesis - The Waiting Room

Emmanuel Macron‏Compte certifié

Plus forts ensemble. Fier du lancement de la coopération structurée permanente pour la défense européenne, pour une Europe qui protège. #EUCO

TIGNARD YANIS‏ @TIGNARDYANIS 1 minil y a 1 minute
En réponse à @EmmanuelMacron.

“Le fatalisme a des limites. Nous devons nous en remettre au sort uniquement lorsque nous avons épuisé tous les remèdes.”
De Gandhi / Lettres à l'Ashram.
“Une petite sincérité est une chose dangereuse et une grande sincérité est absolument fatale.”
De Irène Peter.

Emmanuel Macron‏ Compte certifié @EmmanuelMacron 17 hil y a 17 heures
Toutes mes pensées pour les victimes de ce terrible accident d’un bus scolaire et pour leurs familles. La mobilisation de l’État est totale pour leur porter secours.

En réponse à @EmmanuelMacron
“Pour les hommes, il n'y a jamais eu d'institution aussi fatale que l'argent.”
De Sophocle / Antigone
“La vie est unique et considérable mais la mort d'une grande banalité, comme tout ce qui est fatal.”
De Paul Guimard / Le mauvais Temps.

“L’expression du soi est sacrée et fatale. C’est une nécessité.”
De Marie-Laure Bernadac/ Louise Bourgeois.
“Une connaissance générale est presque fatalement une connaissance vague.”
De Gaston Bachelard/ La Formation de l'esprit scientifique, 1938.

Emmanuel Macron‏Compte certifié @EmmanuelMacron
L’Europe démontre depuis plusieurs mois l’efficacité de l’action coordonnée d’une équipe unie. Le travail continue. Arrivée à Bruxelles pour le Conseil européen. #EUCO

En réponse à @EmmanuelMacron
“Tout ce qui est fixe est fatal et tout ce qui est fatal est puissant.”
De François René de Chateaubriand / Mémoires d’outre-tombe.
“Ces deux mots fatals : le mien et le tien. ”
De Miguel de Cervantès.
Adele - Skyfall

Revenir en haut Aller en bas
Voir le profil de l'utilisateur http://www.atelier-yannistignard.com
yanis la chouette

Nombre de messages : 9682
Localisation : http://yanis.tignard.free.fr/
Date d'inscription : 09/11/2005


14 December 2017

ESA astronaut Paolo Nespoli landed back on Earth early this morning after 139 days in space. The ride home from the International Space Station required braking from 28 800 km/h to a standstill in barely three hours.

Paolo and crewmates Randy Bresnik of NASA and Sergei Ryazansky of Roscosmos touched down on the steppes of Kazakhstan at 08:37 GMT.

The Soyuz MS-05 spacecraft endured the stresses of descent and landing as planned: its heatshield reached 1600°C during reentry into the atmosphere as the astronauts experienced up to four times their own body weight.
Paolo's landing in 2011

At 10 km altitude parachutes deployed before retrorockets provided the final braking metres before touchdown.

“The so-called soft landing feels like a head-on collision between a truck and a small car – and you are in the small car,” recalls Paolo from his 2011 landing.

During his five-month mission, Paolo orbited Earth 2224 times, flew through 35 000 sunrises and sunsets, and travelled 94 million kilometres.

This was Paolo’s third mission and third visit to the Space Station, bringing his total time in space to 313 days, the second most for an ESA astronaut, after Thomas Reiter.

Paolo completed more than 60 experiments during his Vita mission, which stands for Vitality, Innovation, Technology and Ability.

His body was itself an arena for research: his eyes, headaches, sleeping patterns and eating habits were monitored to learn more about how humans adapt to life in space.

Temperature recordings, muscle exercises and plenty of blood and saliva samples will add to the picture and prepare humans for missions further from Earth.

Some 400 km above the planet, he instructed a humanoid robot in Germany to repair three damaged solar panels across a simulated Mars terrain, showing how astronauts and robots will work together on future planetary missions.

Life in space could get easier thanks to tablets and smartphones – Paolo tested a hands-free system that displays instructions during complex tasks.

There was a lot of traffic during Vita: Paolo welcomed four visiting vehicles and saw three leaving the Station. He took part in two dockings using the Station’s robotic arm and assisted in four spacewalks.

Paolo will now be busy with briefings and tests. Astronauts undergo a form of rapid ageing in space and need to readapt to living under gravity. Scientists will investigate how his body reacts as a case study.

The next ESA astronaut to travel to the Station will be Alexander Gerst, scheduled for launch next summer.

"Le moine répond comme l'abbé chante."
Proverbe français ; Le dictionnaire des proverbes et idiotismes français (1827)

"C'est la poule qui chante qui a fait l'œuf."
Proverbe franc-comtois ; Les proverbes et dictons de la Franche-Comté (1876)

"Qui bien chante et qui bien danse fait un métier qui peu avance."
Proverbe franc-comtois ; Les proverbes et dictons de la Franche-Comté (1876)

"Qui rit et chante, son mal espante."
Proverbe provençal ; Les proverbes et dictons en langue d'Oc (1820)

"Reste où l'on chante, les hommes méchants ne chantent pas."
Proverbe rom ; Le dictionnaire des proverbes et dictons tsiganes (1980)

"Au chien de garder la maison, au coq de chanter le matin."
Proverbe vietnamien ; Les proverbes et dictons du Viêt Nam (1956)

"Tous ceux qui chantent ne sont pas gais."
Proverbe russe ; Proverbes et dictons russes (1884)

"Chante à un follet, et il te fera un pet."
Proverbe français ; Les proverbes et dictons communs (1611)

"Autant chante le fou que le prêtre."
Proverbe espagnol ; Dictionnaire des sentences et proverbes espagnols (1892)

"Toute cigale qui chante après le coucher du soleil sera morte le lendemain."
Proverbe provençal ; Le dictionnaire des proverbes provençaux (1823)

"Un riche chargé de fortune quand il crie pense bien chanter."
Proverbe provençal ; Dictons d'oc et proverbes de Provence (1965)

"Même si le coq ne chante pas, l'aurore vient."
Proverbe afghan ; Les proverbes et dictons de l'Afghanistan (1926)

"Quand le laboureur chante la charrue va bien."
Proverbe provençal ; Le dictionnaire des proverbes provençaux (1823)

"Bien danse pour qui la fortune chante."
Proverbe français ; Dictionnaire des sentences et proverbes français (1892)

"L'eau fait pleurer, le vin fait chanter."
Proverbe français ; Trésor des sentences (1568)

"Poule qui chante beaucoup pond peu."
Proverbe allemand ; Dictionnaire des proverbes et idiotismes allemands (1827)

"Un chant doux a trompé plus d'un oiseau."
Proverbe allemand ; Dictionnaire des proverbes et dictons allemands (1980)

"Chacun pense que son coucou chante mieux que le rossignol des autres."
Proverbe allemand ; Dictionnaire des proverbes et idiotismes allemands (1827)

"Comme chante le chapelain, ainsi répond le sacristain."
Proverbe français ; Proverbes et dictons de l'Anjou (1858)

"Le sot est comme un coq qui chante à contretemps."
Proverbe turc ; Mille et un proverbes turcs (1878)

"Quand on entend la grive chanter, cherche la maison pour t'abriter, ou du bois pour te chauffer."
Proverbe agricole ; Proverbes et dictons agricoles de la Dordogne (1872)

"Quand les chouettes chantent le soir, signe de beau temps."
Proverbe agricole ; Proverbes et dictons agricoles de l'Ille-et-Vilaine (1872)

"Si le coucou chante au nord, pluie au lendemain ; s'il chante au midi, beau temps."
Proverbe agricole ; Proverbes et dictons agricoles des Hautes-Alpes (1872)

"Si tu sais chanter des berceuses, que ne t'endors-tu toi-même ?"
Proverbe tadjik ; Dictionnaire des proverbes et dictons tadjiks (1980)

"Là où chantent plusieurs coqs, le jour est en retard."
Proverbe grec ; Dictionnaire des proverbes et dictons grec (1980

"La conversation raccourcit la route, et le chant le travail."
Proverbe russe ; Proverbes et dictons russes (1884)

"La poule ne doit point chanter devant le coq."
Proverbe français ; Recueil d'apophtegmes et axiomes (1855)

"Là où il y a un coq, la poule ne chante pas."
Proverbe breton ; Recueil des proverbes bretons (1856)

"Au fond d'une coquille on écoute les mers, dans l'amour on entend les chants de l'univers."
Proverbe français ; Dictionnaire d'amour (1808)

"Chants de vieillards, chants de plainte qui se terminent par des larmes."
Proverbe malgache ; Le livre de la sagesse malgache (1967)

"Tel chante qui n'a joie."
Proverbe français ; Sentences et proverbes (1892)

"Le jeune coq chante comme il entend chanter son père."
Proverbe français ; Dictionnaire des proverbes et idiotismes français (1827)

"L'oiseau, où qu'il se trouve, chante toujours dans la langue de son pays."
Proverbe géorgien ; Les proverbes de la Géorgie (1903)

"Si tu as faim, chante ; et si tu as mal, ris."
Proverbe yiddish ; Proverbes en yiddish (1977)

"Que le coq chante ou non, le jour se lève."
Proverbe libanais ; Mille et un proverbes libanais (1968)

"Un bon chanteur est capable de chanter, alors même que la demeure croule."
Proverbe kurde ; Les proverbes du Kurdistan (1936)

"Sans le coq qui chante, l'aurore luirait quand même."
Proverbe kurde ; Les proverbes du Kurdistan (1936)

"Où le coq chante, il y a un village."
Proverbe béninois ; Expressions et proverbes du Bénin (2014)

"Si la poule veut chanter comme le coq, il faut lui couper la gorge."
Proverbe persan ; Proverbes et dictons persans (1876)

"Qui a bien chanté le soir a de la peine à chanter le matin."
Proverbe danois ; Dictionnaire des proverbes danois (1757)

"La nuit allonge le jour, et le chant allonge la cruche de bière."
Proverbe finlandais ; Le dictionnaire des proverbes et dictons finnois (1980)

"Qui vit d'espérance meurt en chantant."
Proverbe italien ; Proverbes et dictons milanais (1875)

"L'oiseau qui chante le plus ne construit pas un bon nid."
Proverbe zaïrois ; Proverbes et dictons zaïrois (1994)

"Les chants des colombes rendent les cœurs des amoureux joyeux."
Proverbe mauritanien ; Proverbes mauritaniens (1992)

"Le chant est comme la rosée qui tombe du ciel, il rafraîchit le sentier du voyageur."
Proverbe écossais ; Proverbes et dictons écossais (1876)

"Il y a peu de paix dans la maison où la poule chante et le coq se tait."
Proverbe français ; La fleur des proverbes français (1853)

"Mieux vaut entendre l'alouette chanter que la souris crier."
Proverbe écossais ; Scottish proverbs (1683)

Revenir en haut Aller en bas
Voir le profil de l'utilisateur http://www.atelier-yannistignard.com
Contenu sponsorisé


Revenir en haut Aller en bas
Revenir en haut 
Page 1 sur 1
 Sujets similaires
» Aurore de Maison-Dieu '' Prenez moi tout, mais pas ma fille! ''
» [Lieu] L'église Saint Sauveur de Ryes
» Marie Morgane (Mary Morgan) :
» La religion / les divinités dans la Légende.
» Maison Biscornue et Discussion Tordue... [PV Judas Iscariote]

Permission de ce forum:Vous ne pouvez pas répondre aux sujets dans ce forum
Le clans des mouettes :: Le clans des mouettes-
Sauter vers: