remote sensor

noun
  1. any instrument, such as a radar device or camera, that scans the earth or another planet from space in order to collect data about some aspect of it
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012