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...Cosa vi siete persi !!! Stamattina su RDS hanno fatto sentire nientepopodimeno che i versi delle forme di vita calpestate dalle sonde americane !!!
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Forse abbiamo materiale per una nuova hoax, che ne pensate?http://www.repubblica.it/2007/01/sezioni/scienza_e_tecnologia/omicidio-marte/omicidio-marte/omicidio-marte.html
News ServiceWashington State UniversityPullman, WashingtonContact:Dirk Schulze-Makuch, WSU School of Earth and Environmental Sciences509/335-1180Cherie Winner, WSU News Service509/335-48461/5/2007NEW ANALYSIS OF VIKING MISSION RESULTS POINTS TO THE PRESENCE OF LIFE ONMARSPULLMAN, Wash. -- We may already have 'met' Martian organisms, according toa paper presented Sunday (Jan. 7) at the meeting of the AmericanAstronomical Society in Seattle.Dirk Schulze-Makuch of Washington State University and Joop Houtkooper ofJustus-Liebig-University, Giessen, Germany, argue that even as new missionsto Mars seek evidence that the planet might once have supported life, wealready have data showing that life exists there now -- data fromexperiments done by the Viking Mars landers in the late 1970s."I think the Viking results have been a little bit neglected in the last 10years or more," said Schulze-Makuch. "But actually, we got a lot of datathere." He said recent findings about Earth organisms that live in extremeenvironments and improvements in our understanding of conditions on Marsgive astrobiologists new ways of looking at the 30-year-old data.The researchers hypothesize that Mars is home to microbe-like organisms thatuse a mixture of water and hydrogen peroxide as their internal fluid. Such amixture would provide at least three clear benefits to organisms in thecold, dry Martian environment, said Schulze-Makuch. Its freezing point is aslow as -56.5 C (depending on the concentration of H2O2); below thattemperature it becomes firm but does not form cell-destroying crystals, aswater ice does; and H2O2 is hygroscopic, which means it attracts water vaporfrom the atmosphere -- a valuable trait on a planet where liquid water israre.Schulze-Makuch said that despite hydrogen peroxide's reputation as apowerful disinfectant, the fluid is also compatible with biologicalprocesses if it is accompanied by stabilizing compounds that protect cellsfrom its harmful effects. It performs useful functions inside cells of manyterrestrial organisms, including mammals. Some soil microbes tolerate highlevels of H2O2 in their surroundings, and the species Acetobacter peroxidansuses hydrogen peroxide in its metabolism.Possibly the most vivid use of hydrogen peroxide by an Earth organism isperformed by the bombardier beetle (Brachinus), which produces a solution of25 percent hydrogen peroxide in water as a defensive spray. The noxiousliquid shoots from a special chamber at the beetle's rear end when thebeetle is threatened.He said scientists working on the Viking projects weren't looking fororganisms that rely on hydrogen peroxide, because at the time nobody wasaware that such organisms could exist. The study of extremophiles, organismsthat thrive in conditions of extreme temperatures or chemical environments,has just taken off since the 90s, well after the Viking experiments wereconducted.The researchers argue that hydrogen peroxide-containing organisms could haveproduced almost all of the results observed in the Viking experiments.* Hydrogen peroxide is a powerful oxidant. When released from dying cells,it would sharply lower the amount of organic material in their surroundings.This would help explain why Viking's gas chromatograph-mass spectrometerdetected no organic compounds on the surface of Mars. This result has alsobeen questioned recently by Rafael Navarro-Gonzalez of the University ofMexico, who reported that similar instruments and methodology are unable todetect organic compounds in places on Earth, such as Antarctic dry valleys,where we know soil microorganisms exist.* The Labeled Release experiment, in which samples of Martian soil (andputative soil organisms) were exposed to water and a nutrient sourceincluding radiolabeled carbon, showed rapid production of radiolabeled CO2which then leveled off. Schulze-Makuch said the initial increase could havebeen due to metabolism by hydrogen peroxide-containing organisms, and theleveling off could have been due to the organisms dying from exposure to theexperimental conditions. He said that point has been argued for years byGilbert Levin, who was a primary investigator on the original Viking team.The new hypothesis explains why the experimental conditions would have beenfatal: microbes using a water-hydrogen peroxide mixture would either "drown"or burst due to water absorption, if suddenly exposed to liquid water.* The possibility that the tests killed the organisms they were looking foris also consistent with the results of the Pyrolytic Release experiment, inwhich radiolabeled CO2 was converted to organic compounds by samples ofMartian soil. Of the seven tests done, three showed significant productionof organic substances and one showed much higher production. The variationcould simply be due to patchy distribution of microbes, said Schulze-Makuch.Perhaps most interesting was that the sample with the lowest production --lower even than the control -- had been treated with liquid water.The researchers acknowledge that their hypothesis requires furtherexploration. "We can be absolutely wrong, and there might not be organismslike that at all," said Schulze-Makuch. "But it's a consistent explanationthat would explain the Viking results."He said the Phoenix mission to Mars, which is scheduled for launch inAugust, 2007, offers a good chance to further explore their hypothesis.Although the mission's experiments were not designed withperoxide-containing organisms in mind, Phoenix will land in a sub-polararea, whose low temperatures and relatively high atmospheric water vapor(from the nearby polar ice caps) should provide better growing conditionsfor such microbes than the more "tropical" region visited by Viking.Schulze-Makuch said the tests planned for the mission, including the use oftwo microscopes to examine samples at high magnification, could revealwhether we had the answer all along -- and if we've already introducedourselves to our Martian neighbors in a harsher way than we intended."If the hypothesis is true, it would mean that we killed the Martianmicrobes during our first extraterrestrial contact, by drowning -- due toignorance," said Schulze-Makuch.
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