Washington, April 24 : Researchers at Brown University, US, have found compelling evidence of thick, recurring glaciers on Mars, a discovery that suggests that the Red Planet's climate was much more dynamic than previously believed - and could change again.
The prevailing thinking is that Mars is a planet whose active climate has been confined to the distant past. About 3.5 billion years ago, the Red Planet had extensive flowing water and then fell quiet.
Now, according to research work by scientists at Brown University, the climate of Mars has been much more dynamic than previously believed.
For their research work, Jay Dickson, a research analyst in the Department of Geological Sciences at Brown, and the other researchers focused on an area called Protonilus Mensae-Coloe Fossae.
The region is located in Mars's mid-latitude and is marked by splotches of mesas, massifs and steep-walled valleys that separate the lowlands in the north from the highlands in the south.
After examining high-resolution images taken last year by the Mars Reconnaissance Orbiter, the researchers have documented for the first time that ice packs at least 1 kilometer thick and perhaps 2.5 kilometers thick existed along Mars's mid-latitude belt as recently as 100 million years ago.
In addition, the team believes other images tell them that glaciers flowed in localized areas in the last 10 to 100 million years - akin to the day before yesterday in Mars' geological timeline.
This evidence of recent activity means the Martian climate may change again and could bolster speculation about whether the Red Planet can, or did, support life.
According to the researchers, the images show that Mars has gone through multiple Ice Ages - episodes in its recent past in which the planet's mid-latitudes were covered by glaciers that disappeared with changes in the Red Planet's obliquity, which changes the climate by altering the amount of sunlight falling on different areas.
In another image taken by the Mars Reconnaissance Orbiter, a glacier-like lobe that had spilled from an ancient tributary on to the surrounding plain is shown.
Scientists have said that the lobe is superimposed on a past ice deposit and appears to be evidence of more recent glaciation.
"We've gone from seeing Mars as a dead planet for three-plus billion years to one that has been alive in recent times," said Dickson.
"The finding has changed our perspective from a planet that has been dry and dead to one that is icy and active," he added.