Studying our Earth from Space helps us see it as a planet, and as we explore Mars more and more from the ground, rovers and landers are helping us see how much it is like Earth. 

One of the remarkable discoveries of this century is the presence of dust and dirt covered glaciers just beneath the Martian surface. Like glaciers on Earth, the Martian features end in rubble piles where the glacier deposited debris it had carried with it across the world. In a new study of 45 of these tongs of debris, a team led by Jo Levy has worked backward to figure out how Mars was oriented when the glaciers were deposited, and when over time things happened. 

Unlike Earth, Mars’s orbit and tilt both wander as it is yanked by Jupiter and not stabilized by a moon like ours. As new places on Mars become its north and south poles, glaciers can form in new places, and when Mars strays particularly far from the Sun, it can trigger those glaciers to form. According to this study, published in the Proceedings of the National Academy of Sciences, the locations of glacial debris on Mars indicates that present-day glaciers were deposited at multiple times through Mars history, and “may preserve ice spanning multiple glacial/interglacial cycles, extending Mars climate records back hundreds of millions of years.”

Let me put it another way: Mars has had more than one ice age, and it looks like glaciers from millions of years of periodic ice ages are still on Mars, covered in protective dust and soil, waiting for us to dig in and explore Mars history. This paper was led by Joseph Levy and makes me hope we’ll have glacier-exploring robots in the not too distant future.

More Information

Colgate University press release

“Surface boulder banding indicates Martian debris-covered glaciers formed over multiple glaciations,” Joseph S. Levy et al., 2021 January 26, PNAS