NASA Scientists Seek Fossils of Ancient Mars' Life --"Was There a Common Ancestor? Maybe We're All Martians"
NASA scientists must be prepared to look for fossil evidence of bacterial life on Mars dating back three billion years when most of its atmosphere and possibly existing life vanished in the solar wind. Fossils of early bacterial life more than 3.5 billion years ago have been found on Earth. If similar life ever existed on Mars, NASA has a chance of finding a fossil record of it.
Among other objectives, the rover will look for evidence that life once existed on the red planet. The advisory committee has narrowed the list of landing-site candidates to three and will recommend a finalist later this year. The image above is an artist's impression of Mars four billion years ago. (ESO/M. Kornmesser)
Meanwhile, doctoral candidate, Andrew Gangidine is studying microbial life in silica hot springs in Yellowstone National Park to come up with a useful indicator of life on Mars. For the past two years, he has conducted fieldwork in Yellowstone's geyser basins to examine what elements are associated with bacteria that live in these geothermal pools.
"We want to remain objective. Some people think there has to be life on Mars," Gangidine said. "Others think there certainly isn't life on Mars. And either side has a good chance of being correct. Both have valid arguments. Which is why if we go there and don't see anything, it won't be 'mission fail.'" Gangidine presented his research April 25 at the Second International Mars Sample Return conference in Berlin, Germany.
Today, we know that life cannot exist on Mars, at least not on its dry surface. Solar radiation split most of its surface water into its elemental parts nearly 3 billion years ago when the red planet lost its protective magnetic field.
But scientists are debating whether life might exist somewhere deep underground, among pockets of water trapped around geothermal areas similar to Yellowstone's geysers. "We can look at life being preserved in these silica deposits today. We have evidence of this happening throughout geologic time," Gangidine said. "What we're trying to do is catch fossilization as it happens. What happens to the microbes themselves? And what happens to the trace elements we think are associated with them while they're alive?"
Czaja's NASA advisory committee will meet in October to decide where on Mars they would like to send the rover among the three preferred destinations. The rover is tentatively slated for launch in July or August of 2020, arriving on Mars about seven months later.
"NASA tends to like to go new places to push the frontier. Geologists like to go back to the same places over and over to ask new questions," Czaja said. The rover will collect samples in sealed containers for shipping back to Earth in a later mission. So it could be many years before geologists such as Czaja and Gangidine know whether their hunches about where best to look for life on Mars were correct.
The Mars 2020 mission will not be a failure if scientists find no evidence of life. Quite the contrary, Gangidine said. "If we find it, we can say maybe life is not that rare among planets," Gangidine said. "But if we don't find life in places that would be the most ideal and best preserved candidates, then maybe life is pretty rare."
Any claim about the existence or absence of life on Mars will be subjected to worldwide scrutiny and skepticism. Czaja said researchers must be prepared to provide a wealth of evidence to fortify their findings.
"It's not nearly enough to find something that looks like a bacterial cell," Czaja said. "There are nonbiological things that could look like that. But if you have a cascade of traits -- this and this and this added together -- it's hard to explain it any other way except for life."
The Daily Galaxy via University of Cincinnati
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