[dropcap]M[/dropcap]ADISON — UW-Madison’s Clark Johnson, a geoscientist, has spent years thinking about and studying extraterrestrial life — where we are most likely to find it and what it is probably going to look like.
Don’t expect little green men.
“When I give talks,” Johnson said, “I Photoshop a dinosaur onto Mars’ surface. If we saw that, there’d be no doubt about life. But it is a much more cryptic message that we’re looking for.”
Think more along the lines of something growing underneath a rock, or the telltale clues left by something that once grew underneath the rock.
Johnson leads the Wisconsin Astrobiology Research Consortium, a group with scientist members from around the country and world that studies ancient Earth rocks looking for biosignatures — the signs of ancient microbial life.
Studying such rocks and the stories they tell provides crucial information that can be used to guide the search for life in the extreme environments of planets other than our own, such as Mars.
It is an important enough task that NASA just approved a $9 million, five-year grant for the project. This is the second five-year grant from NASA and will allow the consortium to follow up on work in which it found evidence of microbial life on ancient Earth that dates back beyond two billion years, prior to the time when the planet’s atmosphere contained oxygen.
That’s important because life on harsh planets such as Mars will no doubt look considerably different because of factors such as the lack of oxygen.
“The rise of atmospheric oxygen on Earth about two billion years ago is really the hallmark metabolic process, and we tend to focus on everything since then because we live in an oxygenated world and that’s how we tend to think about biology,” Johnson said.
John Valley, a UW-Madison scientist who specializes in geochemistry, works with the consortium and made headlines in 996 for his studies of a tiny piece of Martian meteorite that appeared to show evidence of fossilized microbes.
It didn’t, in the end. But Valley said in the intervening years, researchers have so improved their tools and approaches that they can spot promising evidence of life on dramatically smaller scales. That’s important because samples future probes bring back from Mars are going to be no bigger than an aspirin.
And, Valley said, researchers working with samples from extreme environments have