Research by planetary scientists at Brown, including doctoral student Ashley Palumbo, find that periodic melting of ice sheets on a cold early Mars would have created enough water to carve the ancient valleys and lakebeds seen on the planet today.
A recent study led by Brown University geologists offers a potential bridge between the “warm and wet” story told by Martian geology and the “cold and icy” past suggested by atmospheric models. The study shows that it’s plausible, even if Mars was generally frozen over, that peak daily temperatures in summer might sneak above freezing just enough to cause melting at the edges of glaciers. That meltwater, produced in relatively small amounts year after year, could have been enough to carve the features observed on the planet today, the researchers conclude.
The study is published online in the journal Icarus. Palumbo led the work with Professor Jim Head, who are both in Brown’s Department of Earth, Environmental and Planetary Science, and Robin Wordsworth, a professor in Harvard’s School of Engineering and Applied Sciences.
Palumbo says the research was inspired by climate dynamics found here on Earth.
“We see this in the Antarctic Dry Valleys, where seasonal temperature variation is sufficient to form and sustain lakes even though mean annual temperature is well below freezing,” Palumbo said. “We wanted to see if something similar might be possible for ancient Mars.”
The researchers started with a state-of-the-art climate model for Mars — one that assumes an ancient atmosphere composed largely of carbon dioxide (as it is today). The model generally produces a cold and icy early Mars, partly because the sun’s energy output is thought to have been much weaker early in solar system history. The researchers ran the model for a broad parameter space for variables that may have been important around 4 billion years ago when the iconic valley networks on the planet’s southern highlands were formed.
Read more of Kevin Stacey's article about cold and icy ancient Mars.