Mars Seems To Be Emerging From Ice Age That Ended 400,000 Years Ago

NASA's Mars Reconnaissance Orbiter gathers new evidence to suggest that the Red Planet is emerging from an ice age that ended about 400,000 years ago. Polar deposits on Mars has given us the information. Just like the earth's ice ages, that era in Mars was driven by long-term cyclical changes in the planet's orbit as well as tilt.

"We found an accelerated accumulation rate of ice in the uppermost 100 to 300 meters of the polar cap," said Isaac Smith of the Southwest Research Institute (SwRI) and lead author of the paper. "The volume and thickness of ice match model predictions from the early 2000s. Radar observations of the ice cap provide a detailed history of ice accumulation and erosion associated with climate change."

Just like the earth, Mars has annual rotation and seasonal cycles, as well as longer cycles influencing its ice distribution. However, such cycles are more likely on Mars as its tilt changes by about 60 degrees during the hundreds of thousands to millions of years. By contrast, the earth's tilt changes only by about two degrees over the same time.

Due to the heightened variability of Mars' tilt, the amount of sunlight hitting the planet's surface also influences the stability of its ice.

"Because the climate on Mars fluctuates with larger swings in axial tilt, and ice will distribute differently for each swing, Mars would look substantially different in the past than it does now," Smith said. "Furthermore, because Mars has no oceans at present, it represents a simplified 'laboratory' for understanding climate science on Earth."

Moreover, the SwRI team concluded that 87,000 cubic kilometers of ice have gathered on Mars' poles ever since its last ice age ended about 370,000 years ago. The study will help scientists to comprehend better the history of polar deposits on Mars as well as their links to factors such as axial tilt, orbital eccentricity, and rotation.

"Studying ice on Mars also is important to the future of human exploration of the Red Planet," Smith added. "Water will be a critical resource for a martian outpost."

The findings were published in the May 27 issue of the journal Science.