Methane kept Mars toasty, study says

In a drying time, Mars may have been kept warm enough for liquid water to remain stable on the surface thanks to explosive bursts of methane gas, a new study finds.

The simulations, described in the journal Nature Geoscience, could explain how Mars managed to sustain a series of lakes in a climate that at first glance seems too cold and arid to have done so.

Since landing on the red planet in August 2012, NASA’s rover Curiosity has discovered that the 96-mile-wide Gale Crater held a series of lakes around 3.5 billion years ago. The rocks Curiousity has drilled and X-rayed and lasered have also revealed environments that would have been potentially habitable for Earth-like life.

Mars’ wettest period, however, was likely the first billion years of its 4.6 billion-year life, the Noachian period, when it had a thicker atmosphere that would have been better able to keep liquid water stable on the planet’s surface.

Then came the 600 million-year Hesperian period, when the planet began to transform from a cold, wet world to a cold, icy one as the protective atmosphere thinned and the planet’s interior cooled. The next 3 billion years until now are known as the Amazonian period, during which Mars solidified its reputation as the cold, dry planet we see today.

But Gale Crater’s rocks bear evidence of liquid water on Mars during the Hesperian period, including lakes — perhaps protected by a layer of surface ice — and deltas.

That means these lakes and deltas persisted during a period that was markedly drier, with a thinner atmosphere less capable of sustaining liquid water.

Lead author Edwin Kite, a planetary scientist at the University of Chicago, and his colleagues say that after running climate models they’ve come up with an explanation — explosive bursts of methane.