The poles of Mars might not be the only place where water ice might be hidden on the Red Planet — now scientists suggest it could also lurk at the equator in craters.
This ice could impact future exploration of Mars, and perhaps even serve as a source of life-sustaining water for any human missions there.
Past research had suggested that water could once be found at the Martian equator. Now, however, the Red Planet's climate is thought to be too harsh, generally, for water to exist — the air on Mars is so thin that any ice on or near the surface of the relatively warm equator would quickly vaporize.
"It always amazes me that something like this could go unnoticed, even with hundreds of thousands of high-resolution images taken from orbit in the past 15 years," Shean told SPACE.com. "I suppose it is a testament to the fact that Mars is full of surprises."
This icy material appears similar to what's thought to be buried ice at midlatitude craters in Mars.
"I've seen thousands of images that show apparently ice-rich material and associated features on the floor of midlatitude craters in both hemispheres on Mars," Shean said. "The big surprise came when I noticed the same material within a crater near the Martian equator."
"A follow-up review of existing data revealed more of this material within nearby craters, and that's when I knew that I was on to something important," he added.
"Our understanding of present-day conditions on Mars suggests that this material shouldn't exist near the equator, period," Shean said. "The fact that it does raises a number of exciting questions about recent climate change on Mars."
Earth's axial tilt, as this slant is called, wobbles slightly but tends to stay within a few degrees of its current position of 23.4 degrees. Mars, on the other hand, currently sits at 25.2 degrees but can sway widely between about zero and 60 degrees.
Computer simulations reveal the extraordinary changes in atmosphere that could result from these wobbles in the Red Planet's angle toward the sun. Such changes would make ice more stable at the equator and cause it to form there when the axial tilt exceeds 35 to 40 degrees, stemming from sources at the poles. This equatorial ice could have then survived in the modern Martian climate if it got buried under debris knocked loose from crater walls.
Shean and his colleagues are now monitoring several locations along the equator for new meteor impacts that could expose buried ice. Still, given how rare these impacts are nowadays and the limited amount of places where this ice might be hidden, "I'm not holding my breath," he said. "We must rely on additional satellite data and modeling studies."
Furthermore, "equatorial sites are attractive destinations for future exploration due to increased insolation — more direct sunlight — and warmer temperatures," Shean said. "These conditions are desirable for solar-powered rovers, but they are also important considerations for future human exploration, which will require accessible water as a life-sustaining resource."
