For an hour, HERA flew as close as 5,600 kilometers from the Martian surface, at a speed of 33,480 kilometers an hour. It used the opportunity to test some of its scientific instruments, snapping around 600 pictures, including rare ones of Deimos.

The results of Hera's fly-by could ultimately tell us whether Deimos is a captured asteroid or made from debris from a giant impact on Mars.

A mission to survey the results of a deliberate crash between an asteroid and a NASA spacecraft has taken stunning images of Mars and its moon Deimos