Evrim Yazgin
Cosmos science journalist
New research into soil samples from Mars suggests its ancient climate was not all that much more hospitable for life than one of Earth’s most desolate areas: Canada.
Specifically, the study found that Mars likely had a cold and icy past climate similar to that in the subarctic climate of Newfoundland in northeast Canada, near Greenland.
In the research, published in Communications Earth and Environment, scientists compared the mineral make up of soil from different locations on Earth to Mars’s Gale Crater. The crater is believed to be a dried-up lake which once had liquid water.
Scientists believe it formed roughly 3.7 billion years ago – about the same time that life first appeared on Earth – when a meteorite crashed into the surface of the planet. Soon after, groundwater filled the crater, creating a lake.
“There was obviously water present,” says Anthony Feldman, a soil scientist and geomorphologist now at the Desert Research Institute in the US. “But what were the environmental conditions when the water was there?”
“We’re never going to find a direct analogue to the Martian surface, because conditions are so different between Mars and Earth. But we can look at trends under terrestrial conditions and use those to try to extrapolate to Martian questions.”
Gale Crater has been explored by NASA’s Curiosity rover since 2011.
Curiosity found soil in the crater is made up of strange components known as “X-ray amorphous material.” These materials lack the repeating structure which defines minerals and produce identifiable “fingerprints” when X-rays are shot at them.
“You can think of X-ray amorphous materials like Jello,” Feldman says. “It’s this soup of different elements and chemicals that just slide past each other.”
The rover’s chemical analyses on the soil and rock samples shows that the material is rich in iron and silica, but has low levels of aluminium. But the origin of these materials and their relationship to Mars’s environment has eluded scientists.
To gain insight into the amorphous materials, the researchers looked for soil samples on Earth which shared some of the characteristics of those found in the Gale Crater.
They tested soils from 3 sites in North America: The Tablelands of Gros Morne National Park in Newfoundland; California’s Klamath Mountains; and western Nevada. These locations also provided a range of rainfall, snowfall and temperature.
Subarctic conditions of Newfoundland produced materials chemically similar to those found in Gale Crater. The warmer climes of California and Nevada did not.
“This shows that you need the water to form these materials,” Feldman says. “But it needs to be cold, near-freezing mean annual temperature conditions in order to preserve the amorphous material in the soils.”
“This study improves our understanding of the climate of Mars,” Feldman says. “The results suggest that the abundance of this material in Gale Crater is consistent with subarctic conditions, similar to what we would see in, for instance, Iceland.”
While this does not rule out the possibility of life on ancient Mars, it does suggest that the Red Planet may have been too cold to produce the same conditions which sparked the origins of life on Earth around the same time.
