LOS ANGELES, Jan. 20 (Xinhuanet)-- Glaciers covering the tropical regions of Mars may have come from snow, rather than water sources bubbling up from the ground, a new study indicated.

The Red Planet

    Based on a blend of geological observations and climate modeling, the study conducted by a team of American and French scientists is expected to end a 30-year Martian mystery. The finding appeared in the Jan. 20 online edition of the journal, Science.

    In 1976, cameras aboard NASA's Viking Mission to Mars first captured views of the canyons and craters of the red planet, including polar ice caps. Recent spacecraft data reveal curious rock-strewn deposits found at the foot of volcanoes and mountains close to the equator.

    In the last two years, experts have offered more evidence that these ice-rich landforms, which appear to ooze out of valleys and volcanoes in mid-latitude and tropical Martian regions, are the remnants of geologically recent glaciers.

    But how could ice form so far from the planet's poles? The researchers, led by Brown University planetary geologist James Head, said the glaciers were formed from snow brought from the polar regions.

    A few million years ago, the researchers explained, the axis of Mars was tilted in such a way that the poles were pointing dramatically closer to the sun. Sun rays hit the polar ice caps nearly head on, releasing massive amounts of water vapor into the atmosphere.

    Monsoon-like winds carried the water vapor south, up and over the soaring slopes of the volcanoes and mountains. The vapor cooled, condensed, and fell in the form of snow.

    Over time, the snow turned to ice, the ice formed glaciers, and the glaciers created the deposits seen today, the researchers said.

    "This agreement points to an atmospheric origin for the ice and reveals how precipitation could have formed glaciers on Mars," they wrote in the Science paper.

    The Martian precipitation cycle is similar to the one on Earth which routinely blankets mountainous regions such as the Rockies in snow.

    The tropical mountain glaciers described in the article can also be found in places such as Mount Kilimanjaro in Africa or the Andean peaks in South America, according to the paper.

    The researchers used a climate model that simulated the present-day Martian water cycle but assumed a 45-degree axial tilt found on the planet millions of years ago.

    The model created a near-perfect match of predicted ice accumulation and direct observational evidence from images taken by the Mars Express, Mars Global Surveyor and Mars Odyssey orbiters.

    "The findings are important because they tell us that Mars has experienced big climate changes in the past, the kinds of climate change that led to the Great Ice Age here on Earth," Head said in a statement.

    "The findings are also interesting because this precipitation pattern may have left pockets of ice scattered across Mars. This is good information for NASA as officials plan future space missions, particularly with astronauts." Enditem