Impact ejecta, according to http://www.planetary.org/blogs/emily-lakdawalla/2016/01281656-fun-with-a-new-data-set-change.html http://www.planetary.org/blogs/emi

Impact ejecta, according to http://www.planetary.org/blogs/emily-lakdawalla/2016/01281656-fun-with-a-new-data-set-change.html http://www.planetary.org/blogs/emily-lakdawalla/2016/0128165...