NASA radar checks out ECAs, Earth-orbit crossing these, in case one is about to wipe out civilization
These 
radar images of asteroid 2012 DA14 (looped 9 times) were taken... [DOC] [TLE] From a Million Miles: The Moon Crossing the Face of Earth - NASA [PAR] Aug 5, 2015 ... From a Million Miles Away, NASA Camera Shows Moon Crossing Face of Earth 
... telescope on the DSCOVR satellite orbiting 1 million miles from Earth.