Why is Mars so dry?

We have long been fascinated with the planet Mars. It has been called ‘the red planet’ and it wasn’t too long ago that some thought there were actual civilizations that existed on Mars. The ancient Greeks and Romans named it after their god of war and the ancient Egyptians called it ‘the one that blushes’. As we began sending missions to Mars, we found out that none of that was true. No one lived on the planet, and instead, it was a dry, dusty planet. So what happened to Mars to make it so dry?

view of Martian soil and boulders after crossing the "Dingo Gap"

Mars is thought to have once been similar to our own earth. It is close in size, and close enough to the sun that it might have actually had life on it. Thanks to the Mars rovers, we have discovered a lot of things about Mars. An important aspect is that it is covered in a fine layer of reddish rust dust. Underneath the dust are volcanic rocks that are not unlike those of earth. It does have a very light atmosphere, but not enough to actually allow life to exist.

For years, scientists have been wondering what happened to Mars. It is thought that at one point, there was liquid water on Mars and that it possibly could have had microbial life. Many areas of the landscape on the surface of Mars looks like it would have had waterfalls. There are also other areas that look like earth, where water has caused erosion.

image of Valles Marineris.

One of the theories that scientists have includes the possibility that Mars could have had what is called a ‘runaway greenhouse effect’. This is where too much carbon dioxide enters the atmosphere and it causes the planet to heat up and continue heating. This is similar to what our scientists are currently studying about ‘global warming’ on the earth. When the temperature gets too high, it boils off all of the water on the surface and eventually the atmosphere exits into space. This leaves the surface completely dry.

Another reason that Mars may have lost its water and atmosphere is due to the fact that it lost its magnetic field. Earth has a magnetic field and it plays an important part in keeping the high radiation from the sun away from the surface of the planet. Without a magnetic field, the atmosphere could blow away in the solar wind.

Mars Rocks

In November, 2013, NASA sent off a new space mission to Mars, called MAVEN (Mars Atmosphere and Volatile Evolution). The purpose of this mission is to examine the Mars surface using new technologies. Scientists already believe that there may be a large amount of water beneath the surface of Mars, but they really aren’t sure.

Mars does have ice at the polar caps, so this is another area that helps to prove the history of Mars. The MAVEN mission should help by giving more information about what is under the surface, what the thin atmosphere is made of as well as what the polar caps are made of. This will help scientists to make decisions about what happened to Mars and why it is so dry.