2001 MARS ODYSSEY (orbiter) – created maps, measured radiation, identified buried water ice, became com relay for landers
2003 SPIRIT and OPPORTUNITY (rovers) – geology/atmospheric observations evidence of wet/habitable conditions in past
2003 MARS EXPRESS (orbiter) – evidence of glacial activity, volcanism, and methane gas
2005 MARS RECONNAISSANCE ORBITER (orbiter) – sounder for subsurface water location, identifies safe landing spots, provides com relay
2007 PHOENIX SCOUT (lander) – hi-res of landing sites, scanned clouds, fog, dust, etc.