700 Kilometers Below Comet Hartley 2 . ... Credit Copyright: NASA , JPL-Caltech, UMD , EPOXI Mission Explanation: What kind of comet is this? Last week, NASA's robotic EPOXI spacecraft whizzed past Comet 103P/Hartley , also known as Comet Hartley 2, and recorded images and data that are both strange and fascinating. EPOXI was near its closest approach -- about 700 kilometers away -- when it snapped the above picture . ... How much of Comet Hartley 2 is a loose pile of dust and ice shards? ...