Mars May Be Too Cold For Life
Curiosity is busy searching for evidence of habitable environments on Mars.
Long-distance-moving pebbles and mountains growing out of lake deposits -- this was the Mars of several billion years ago, showing extensive evidence of
water shaping the landscape. While hard to imagine when looking at images of the dust-swept Martian landscape of today, NASA's Curiosity rover has gathered a lot of information showing how the rocks were shaped and formed by liquid water. Here are some of its key findings.MORE: The Martian (Water) Chronicles
Image: This self-portrait of NASA's Curiosity Mars rover shows the vehicle at the "Big Sky" site, where its drill recently collected the mission's fifth taste of Mount Sharp.
Pebbles like this on Mars were long-distance travelers,perhaps moving as far as 30 miles on Mars
. The research team that came up with this figure based their work both on how the stones were shaped -- they had a model predicting how the stones change as they scrape against other objects -- and erosion tests from observations in the lab, Puerto Rico and New Mexico.MORE: Mars Pebbles Carried for Miles by River
Image: Curiosity's images of rounded pebbles show evidence that they were shaped and carried by water on ancient Mars -- imagine rocks being carried by babbling streams and rivers flowing down the slopes of Gale Crater and you wouldn't be far wrong.
This picture of the "Kimberley" formation shows strata (rock layers) that are lower near the base of Mount Sharp, the informal name that NASA gives to Aeolis Mons. This shows how thewater flowed into a probable lake
about 3.3 billion to 3.8 billion years ago, before the mountain formed. While the skies look blue in this image, don't be fooled; engineers color-adjusted the image so that it looks similar to colors on Earth. This assists geologists with making comparisons between our planet and the Red Planet.MORE: Mars Rover Finds Gale Crater was Once a Big Lake
These veins are the leftovers of fluids that brought minerals with them. These minerals fell into the cracks of a rock that was already broken apart andchanged the chemistry of the rock itself
. The veins are so resistant to erosion that they today stand prominently on Mars, up to 6 centimeters (2.5 inches) high around the bedrock, which was softer and eroded over the eons.MORE: Curiosity Has Hit a Martian Mineral Jackpot
Mount Sharpgrew through river deposits
, according to data obtained from the Curiosity rover -- indicating that water could have persisted on the Red Planet for a long time. NASA describes these pictured rocks as typical of what you would find under river deposits; it uses words such as "thick-laminated" and "evenly-stratified". Geologists looking at this formation, on the edge of "Hidden Valley", are believed to show the remains of sediments that fell on to a lake floor nearby where a flowing river brought in water. The colors have been corrected to look approximately like what you would see on Earth, for better comparisons.PHOTOS: When Liquid Water Gushes on Mars
Within weeks of landing in August 2012, Curiosity stumbled upon a major find: a dry riverbed, showing that water flowed not far from where the rover landed in Gale Crater. Several sites showed evidence of this water,including "Hottah."
From looking at how big the stones were and seeing that they were rounded, the scientists estimated that the water moved at about three feet per second, somewhere between ankle and hip deep.MORE: Curiosity's Mars Crater was Once a Vast Lake
Microbes appear to be dormant in permafrost in a region of Antarctica, which could deal a blow for the search for life in similar regions on Mars.
A group of researchers found negative tests for microbial activity at temperatures below freezing in a region called University Valley, in Antarctica’s McMurdo Dry Valleys. However, in spots just a little above freezing (5 Celsius, or 41 Fahrenheit), the same team found five bacteria and one yeast.
“Detecting activity at this temperature indicates that at least some of the biomass in University Valley soils is viable, and these cells are likely currently dormant and surviving until more favorable conditions come along,” said Jackie Goordial, the principal investigator of the research.
She acknowledged, however, that if only a few cells were active in the permafrost, they could have eluded the detection limits of her instruments. “We also assayed for activity using the same tests we would normally use for other permafrost environments, and which are normally successful,” added Goordial, a postdoctoral fellow in environmental microbiology at McGill University in Montreal, Canada.
McMurdo has been likened to the Phoenix landing site on Mars, which is also at high elevation and at a pole (the north pole, in this case). That said, there have been microbes found in colder temperatures on Earth.
The “champ” is called Planococcus halocryophilus, Goordial said, and it is found in the Ellesmere Island permafrost at the Canadian high Arctic. It reproduces at temperatures down to -15 degrees Celsius (5 Fahrenheit) and can metabolize down to at least -25 Celsius (-13 Fahrenheit). So the new findings come as a bit of a surprise.
We are also hoping to go back to University Valley to obtain more and deeper samples from this site to see if the deeper and older permafrost become truly ‘dead’, which would be our working hypothesis,” said Goordial.
“Our results also indicate that University Valley permafrost soils will be excellent analogues to develop and test life/biosignature detection instruments to be sent if future missions to Mars as well as Europa and Enceladus because of the extremely low biomass present,” she added, referring to icy moons of Jupiter and Saturn (respectively).
These mineral veins on Mars, spotted by the Curiosity rover, were believed to have formed in a wet environment.NASA/JPL-Caltech/MSSS
McMurdo has been an active region for microbe-hunting. Much of the literature, Goordial said, focuses on lower and mid-elevation areas that have a lot more microbe biomass and diversity. Notable microbial regions include Lake Whillans and Blood Falls, she said.
Even the walls of University Valley have cryptoendoliths (microbes hidden within rocks) that are in regions heated by the sun with humidity traps. Inland and elevated areas tend to have more cold, arid and harsh conditions.
“We think that the warmer, wetter conditions are why the walls can support active life, but the ground cannot. In the paper we show that using the same activity assays we used for the soil, we can detect microbial activity down to -20 C [-4 F] in the cryptoendolithic communities, so they certainly seem cold-adapted,” Goordial said.
“I would also like to add that this work means we can’t use the lower dry valleys as a valid Mars analog. No more looking in the places where life is easy to find. We need to focus on the places where life is hard to find. We need to test the methods and approaches in these hard places before we go to Mars.”
Goordial’s research was published in The ISME Journal.