Boiling water turns sand into hovercraft

摘要

THE sand on Mars may be floating on air. Warm temperatures in the Martian summer, combined with a thin atmosphere and deposits of ice may cause sand to levitate and carve out deep gullies. Mars can get quite balmy in the summer, reaching temperatures up to 20℃. That's warm enough to melt some of the ice deposits scattered across the planet. But because Mars has just one-hundredth the atmospheric pressure of Earth, that water doesn't stay liquid for long on the surface before boiling away.