Even though Mars is half the size of Earth, it has the biggest volcano, the biggest impact crater, the biggest canyon and also a dune field about the size of the Sahara Desert – about 1 million square kilometers in size. Scientists are unsure if this dune field or the Sahara Desert is the biggest dune field in the solar system. These dunes are located around the northern polar cap.How do dunes form on Mars? And why are these dunes so frequently shifting in shape and size? On Earth we know that it takes a lot of wind power to create dunes. Since Mars has a thin atmosphere the wind average wind speed is 12 miles per hour. The Viking landers studied wind speed over a year and recorded wind gust from 50 to 60 miles per hour.
Oddly enough, the conditions on Mars make forming dunes much easier than on Earth. For one, the gravity is lower and so is the air density. Both these factors mean less air resistance. When the wind picks up on Mars, particles are going to go much farther than on Earth. When the sand (or dust) comes back down it hits the ground and kicks up more particles. This keeps the sand going.These conditions have also produced dunes that are twice as tall as the ones on Earth. The Mars Global Surveyor has used stereo-images to reveal dunes between twenty and three hundred feet high.
These dunes also move over years.
In any case, Dunes present problems to any future explorers. They would be hard to travel through and the risk of clogging equipment would be great. These dunes can also hide craters or jagged ledges. And yes, there is something about dunes in my book.