The words “Mars” and “habitable” don’t really go together in the same sentence when you’re looking at a planet that’s been stripped of its atmosphere by brutal solar winds, and is cold and dehydrated enough to freeze-dry you overnight. Even with the alien outlook bleak as it is, the chance for some sort of life-forms once having existed on the Red Planet just skyrocketed.
Curiosity has beamed back data from its Alpha Particle X-Ray Spectrometer (APXS) that suggests chemical evidence of what could have been habitable conditions several billion years ago. Higher concentrations of the elements zinc and germanium that suggest possible hydrothermal activity were unearthed in the sedimentary rock of the planet’s Gale Crater. These elements gravitate toward each other in minerals that surface after hot fluids evaporate, and at least on Earth, occur together in sulfuric hydrothermal deposits.
Hydrothermal systems could have occurred on ancient Mars if the area Curiosity zeroed in on had enough water after a meteor impact left the Gale Crater—and possibly enough energy to heat the surrounding crust—in its wake. Sufficient levels of heat would have caused fluids containing concentrated zinc and germanium to swirl around in a hydrothermal system. The concentrations of these elements may also even been the result of volcanic eruptions or other impacts from objects in space. Wind, water and gravity are thought to have carried them over to the Gale Crater back when there was such a thing as a Martian atmosphere.
"You have heat and chemical gradients ... conditions favorable for the genesis and persistence of life," said geologist Jeff Berger, who led a new study recently published in Journal of Geophysical Research: Planets.
While past rovers have picked up on such evidence and scientists back on Earth have used computer simulations of long-ago conditions on Mars alongside lab experiments and close examination of our own planet’s hydrothermal sites, Curiosity creeps even closer to uncovering what Mars was like before it turned to a ball of red dust with this additional find. Most of Mars has levels of germanium that elude the AXPS detection limit, which is why it came as a surprise to investigating scientists. The Gale Crater’s germanium content is up to 100 times higher (even 300 in one vein) than that of your average Martian meteorite.
Even more exciting is that there is a greater possibility of finding preserved microbes similar to the first life that emerged on Earth.