Ice Sheet on Mars 30 Times Thicker than Thought

According to new calculations made by astronomers, it would appear that the layer of dry ice previously found at the south Martian pole is about 30 times thicker than initially calculated.

Dry ice is a solid form of carbon dioxide. The chemical turns into a solid at minus 78.5 degrees Celsius (−109.3 °Fahrenheit). On the surface of Mars, temperatures go even lower than these levels.

Data supplied by the Mars Odyssey orbiter revealed that existence of polar dry ice caps at both Martian poles, and subsequent studies carried out with a variety of other spacecraft have confirmed the finding.

The investigations also managed to survey the depth of the ice sheets, but apparently this was not as successful as experts had hopes. A new study carried out with the Mars Reconnaissance Orbiter (MRO) determines that the dry ice layer is significantly thicker than originally thought.

If this discovery holds true, then this could mean that the Red Planet was a much wetter place in its distant past. It may be that the ocean hypothesized to have existed in its northern hemisphere was actually a reality, and not just some anomaly or scar on the Martian surface.

During the new MRO study, a radar instrument onboard the orbiter revealed that the ice layer is about 2,300 feet (700 meters) thick. “The volume of the deposit is about the volume of Lake Superior,” explains Southwest Research Institute expert and study leader Roger Phillips.

Finding out such details about the polar caps is very important for making more sense of the way Mars' climate is set up. The amount of carbon dioxide that gets trapped at the poles is apparently determined by how muck the entire planet shifts its tilt.

While the Moon stabilizes Earth to an inclination of 23 degrees 44 minutes, Mars can change its inclination between 0 and 60 degrees, and this seems to control the way ice is stored or released.

“When the tilt axis of the planet – the obliquity – is very high, higher than it is now, the carbon dioxide is released into the atmosphere. When the obliquity is low it goes back into the polar caps,” Phillips explains, quoted by Space.

One of these CO2-capture-release cycles lasts for about 100,000 years, experts say. According to the team, the discovery indicates that certain periods in Mars' distant past saw larger accumulations of water developing on the planet.

This doesn't necessarily mean that more lakes or river beds were produced. What it does mean is that cosmic radiation and Sun-generated particles did not strip off the water from the planetary surface as fast as they do today.