The search for life on Mars has been intimately linked to the search for water. Now, NASA reports that its Curiosity rover has detected evidence of water chemically embedded in fine-grained Martian dust, stirring renewed interest the search for ancient life on the Red Planet after hopes had fallen earlier this year.
The new report comes from Curiosity’s laser-shooting Chemistry and Camera (ChemCam) instrument, which picked up a hydrogen signal in a representative soil sample, suggestive of water. Meanwhile, Curiosity’s Chemistry and Mineraology tool (CheMin) found no sign of water in soil samples from a sandy dune called Rocknest. But because CheMin uses high-energy reflected light as its main detection apparatus, it can’t see soil that’s in a non-crystalline form.
Here’s Amina Khan writing for the Los Angeles Times:
All this means the hydrogen signal seen by ChemCam must have been coming from the amorphous, or non-crystalline, portion, which makes up a significant minority of the soil, said Bish, who led the CheMin study.
Sure enough, Curiosity’s Sample Analysis at Mars instrument cooked up a tiny sample in its little oven and found that roughly 1.5% to 3% of the soil was made of water. The scientists think this water may have come from the atmosphere, pulled out of the thin air.
While scientists had announced earlier this year that they found signs of an ancient, fresh-water lake within Gale Crater, this new data suggests that the lake was part of a more complex habitable environment replete with rivers and groundwater. “We see evidence for a more evolved planet,” Grotzinger told the Times, “so it looks like it was headed in more of a direction like Earth.”
Of course, scientists don’t yet know what lies beyond Curiosity’s current playground. Here’s Joel Achenbach writing for The Washington Post:
Mars has as much land surface as Earth, and only a tiny fraction of the planet has now been explored by the rovers. The fact that Curiosity found signs of an ancient lake with benign chemistry suggests that Mars was broadly “habitable” — potentially an abode of life — billions of years ago.
Mars has lost much of its atmosphere since, and dried out, and become a cold, hostile environment with no obvious signs of extant life, though there could be “cryptic” life below the surface.
Do 4-billion-year-old microfossils lie buried in Martian rock? We have no way of knowing right now, but NASA hopes to launch return missions that would try to find out.
Relive Curiosity‘s harrowing descent along with its travels and discoveries on the Red Planet in our interactive timeline.