Liquid brine can hang around on Mars’ surface, a new study suggests,
but conditions may not be great for life as we know it.
That’s bad news for any Earth-based microorganisms determined
to colonize the Red Planet, but good news for humans who don’t want to
contaminate Mars with microbes hitching a ride on robot explorers.
Pure liquid water can’t last on Mars’ frigid surface. But
mix in some salts, and H2O might stick around for a bit. NASA’s
Curiosity and Phoenix landers have detected salts known as perchlorates in the
Martian soil, and researchers have suggested that such salts might make
transient brines possible (SN: 3/20/09).
No salty liquid water has been definitively found on Mars.
But there have been hints of water dribbling
out from underground (SN: 9/28/15),
and a controversial report of a
buried lake near the Red Planet’s south pole (SN: 12/17/18).
To learn more about how brines would behave in contemporary
Martian conditions, Edgard Rivera-Valentín, a planetary scientist at the Lunar and
Planetary Institute in Houston, and colleagues ran computer simulations. They
found that one type of brine could remain liquid on the planet’s surface and a
few centimeters below for up to six consecutive hours
across 40 percent of the planet, mostly at middle to high northern
latitudes. However, those brines would never get warmer than about –48° Celsius, about 25 degrees below the
known tolerance for life on Earth, the team reports online May 11 in Nature
This finding is useful for anyone planning a mission to
Mars, the researchers say. Expeditions to locales with the potential for liquid
water are subject to
strict protection protocols (SN: 10/29/19) to reduce the risk of
contamination from Earth. If Martian brines are truly uninhabitable by any
known organism from our planet, that may ease restrictions on future