What's painting dark streaks on Mars?
来源：未知 作者：柏购疗 时间：2019-03-09 05:20:02
WHAT’S painting Mars? Every spring, dark streaks appear on its polar dunes, which may be caused by liquid water near the surface – a fillip for the hunt for life. The dark streaks of sand a few metres wide slide downslope at about a metre a day. “They show a branching pattern, so it seems like some liquid material is flowing,” says Akos Kereszturi at the Collegium Budapest in Hungary. Kereszturi reckons they occur when molecules in surface water ice are attracted to molecules in the minerals below. His team’s computer models suggest this melts an ultrathin layer,