Satellite sensors     Remote sensors perform in three different ways: 1) detecting passive reflection of EMR, 2) detecting passive emitted EMR, and 3) transmitting a signal and detecting its return time from the target (radar) Source: 2003 GEOS 422 Lecture , A. Prakash, UAF   Radarsat1 satellite is an example of an active sensor Source: http://www.space.gc.ca/asc/eng/csa_sectors/earth/ radarsat1/radarsat1.asp     Meteosat is a passive multisensor satellite used for communications, meteorology, and land use applications. It is owned by the European Space Agency Source: http://ceos.cnes.fr:8100/cdrom-98/ceos1/site_map.htm