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Mars crater with ice. Image credit: ESA
It is a well known fact that Mars is cold world. Some people wonder, since it is cold, does it snow on Mars? Yes, it does. That fact is a fairly new discovery. NASA’s Phoenix lander was the first to discover the snow in 2008.
The Phoenix lander began its descent into the Martian atmosphere, at the northern pole, in September, 2008. AT about 4km above the surface it observed snow fall, but the snow evaporated before it could reach the surface. The find was very surprising given the low amount of water in the thin atmosphere. At first scientists suspected that the snow would never reach the surface of the Red Planet. They were surprised as the winter season progressed. Phoenix began returning images of snow on Mars’ surface. Unfortunately, the lander’s solar panels became covered and it was unable to charge its batteries. Without power it was unable to keep its electronics warm and shutdown.
Snow on Mars does not appear to be a new event. Other spacecraft have returned data that seems to show evidence of glaciers covering vast areas of the planet’s surface in the ancient past, reaching nearly to the equator. It possible that millions of years ago, Mars was more tilted towards the Sun. The increased heat on the polar ice caps melted them, releasing more water vapor into the atmosphere. This water would have returned to the surface as snow, creating the vast glaciers. Those glaciers retreated when the planet’s axial tilt shifted once again.
Another fact that surprises many people is the large amount of water ice there is on Mars. Many scientists had thought that any ice on Mars would be carbon dioxide ice, since the planet’s atmosphere is 96% CO2. The Phoenix lander had a primary mission to dig into the surface of the planet looking for ice to determine its nature. The lander used its robotic arm to expand a small trench. After doing so, it exposed several shiny objects that were determined to be ice of some nature. The objects vaporized after four days. Scientist used that time frame to determine that the ice was water ice. Carbon dioxide ice would have vaporized much more quickly. Additional tests were done by heating soil samples. The sample released all of the components necessary to indicate the presence of water ice under the Martian surface.
The presence of water and snow on Mars are encouraging signs for the future of manned exploration of the planet as well as clues that keep hopes alive for past life on the Red Planet. As new instruments are developed, who knows what will be found.
We’ve written many articles about snow and ice on Mars. Here’s an article about snow falling from Martian clouds, and here’s an article about how it snows at night on Mars.
If you’d like more info on Mars, check out the homepage for NASA’s Mars Exploration program. This is where all the latest Mars news is announced.
We’ve also recorded several episodes of Astronomy Cast about Mars. Listen here, Episode 52: Mars.
Sources:
http://www.jpl.nasa.gov/news/news.cfm?release=2008-183
http://www.jpl.nasa.gov/news/news.cfm?release=2008-113
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