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5 December 2013 11:26 am ,
Vol. 342 ,
Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
Thousands of scientists in the Russian Academy of Sciences (RAS) are about to lose their jobs as a result of the...
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
Snake venoms are remarkably complex mixtures that can stun or kill prey within minutes. But more and more researchers...
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
Since arriving on the island of Guam in the 1940s, the brown tree snake ( Boiga irregularis ) has extirpated native...
- 5 December 2013 11:26 am , Vol. 342 , #6163
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Missed Opportunity on Mars?
8 January 2007 (All day)
Did NASA kill alien lifeforms thirty years ago? Maybe. According to two astrobiologists, NASA's Viking landers, which touched down on Mars in 1976 to search for life on the Red Planet, may actually have destroyed Martian micro-organisms in the process.
The Viking experiments were designed to look for Earth-like life on the Mars. Samples of Martian soil, scooped up by the spacecraft's robotic arm, were exposed to a variety of in-situ tests. In one experiment, nutrient-rich water was added to the sample to see if any organisms that might be present would feed themselves. Another experiment cooked the sample to see if any organic residue would be left.
But according to geologists Dirk Schulze-Makuch of Washington State University in Seattle and Joop Houtkooper of the Justus Liebig University in Giessen, Germany, Martian micro-organisms may be radically different from Earthly water-based life-forms. In particular, the fluid in their cells may not be water, but a mixture of water and hydrogen peroxide. That may explain the origin of a highly oxidizing chemical substance on the Martian surface, thought to be hydrogen peroxide. According to Schulze-Makuch and Houtkooper, the aggressive stuff might have a biological origin.
If such organisms exist on Mars, they would not have survived the Viking nutrient experiment, the researchers report. Instead, they would have been literally drowned to death, because they wouldn't be able to cope with large quantities of water. Also, the cooking experiment would not leave organic residue, because organic molecules would be destroyed by the released hydrogen peroxide.
Schulze-Makuch's presentation here at the 209th meeting of the American Astronomical Society drew a lot of media attention, but it was greeted with cautious skepticism by other scientists. "It's a pretty neat idea," says Michael A'Hearn, an astronomer at the University of Maryland, College Park. But even though it looks like the Viking experiments could indeed have killed hydrogen peroxide-based organisms, that doesn't necessarily mean life exists on Mars, he says. Astrobiologist John Baross of the University of Washington in Seattle agrees that it is certainly conceivable that the Viking experiments failed to detect alien micro-organisms. Still, he says, "I can't imagine any carbon-based life form that could survive close to the Martian surface, given the high levels of lethal radiation."