Mysterious Lines on Mars Are Result of Dry Ice

Images of lines drawn in the sand of Martian dunes have puzzled scientists for years. As it turns out, those linear shapes are the result of dry ice gliding down the slopes.

The mile-long troughs on Mars, which scientists first spied in 2002, are unusual because they abruptly end in a pit, unlike similar lines on Earth that end in "debris aprons," as the rolling material is deposited at the bottom

"In debris flows, you have water carrying sediment downhill, and the material eroded from the top is carried to the bottom and deposited as a fan-shaped apron," said Serina Diniega, a NASA planetary scientist. "In the linear gullies, you're not transporting material. You're carving out a groove, pushing material to the sides."