Mars scientists dubbed them recurring slope lineae or RSLs. They sure looked like evidence of liquid water flowing down hillsides and ridges on the Red Planet. New research led by US Geological Survey Planetary Geologist Colin Dundas says they are probably no more than dry sand and dust. Emily Lakdawalla reports that NASA has narrowed the choices for the next New Frontiers mission to a Titan or a comet lander. And it’s time for the last 2017 What’s Up look around the night sky by Bruce Betts.
NASA / JPL / UA / Emily Lakdawalla
Recurring slope lineae (RSL) in Newton Crater, Mars
Recurring slope lineae are narrow (0.5-5 m wide), relatively dark-toned features that form on steep (25-40˚), southern-hemisphere slopes, and that appear in early spring, grow longer in the downslope direction during spring and summer, and fade during autumn and winter.