Dry Ice Sled Streaks on Mars . ... Credit Copyright: HiRISE , MRO , LPL (U. Arizona) , NASA Explanation: What creates these long and nearly straight grooves on Mars? ... A leading hypothesis -- actually being tested here on Earth -- is that these linear gullies are caused by chunks of carbon dioxide ice ( dry ice ) breaking off and sliding down hills while sublimating into gas, eventually completely evaporating into thin air. ... NASA Web Site Statements, Warnings, and Disclaimers . ...