Scientists have long known about glacial events on Mars, which are driven by variations in the planet's orbit and tilt.
If melted, the newly discovered polar ice would be equivalent to a global layer of water around Mars at least 1.5 meters (5 feet) deep.
The layers formed when ice accumulated at the poles during past ice ages on Mars. Each time the planet warmed, a remnant of the ice caps became covered by sand, which protected the ice from solar radiation and prevented it from dissipating into the atmosphere.
"Understanding how much water was available globally versus what's trapped in the poles is important if you're going to have liquid water on Mars,"
"You can have all the right conditions for life, but if most of the water is locked up at the poles, then it becomes difficult to have sufficient amounts of liquid water near the equator."
article - Blogs.discovermagazine.com
