Passing in the Night
In the past half-century, mankind has lifted itself from the surface of its world and thrown messages into the black of space. Space is big - impossibly so - and our spacecraft pass in the night without even knowing it.

Usually.

Sometimes, though, these little packages from Earth get a chance to see each other. These are those pictures - those little waves across the void.

(This is not a full catalogue of such images - primarily because the Mars Reconnaissance Orbiter seems to delight in taking ultra-long-distance shots of various landers, most of which don't look all that different from each other)
Spirit
Earth, 2004, by Spirit
Spirit, 2005, by the Mars Global Surveyor
Spirit, 2006, by the Mars Reconnaissance Orbiter
Spirit's parachute and lander, 2006, by the Mars Reconnaissance Orbiter
Spirit, 2009, by the Mars Reconnaissance Orbiter
Spirit's lander, 2012, by the Mars Reconnaissance Orbiter
Opportunity
Opportunity's parachute, heatshield and lander, 2004, by the Mars Global Surveyor
Opportunity's heat shield, 2005, by Opportunity
Opportunity, 2009, by the Mars Reconnaissance Orbiter
Opportunity, 2010, by the Mars Reconnaissance Orbiter
Opportunity, 2011, by the Mars Reconnaissance Orbiter
Opportunity's three locations, 2009-11, by the Mars Reconnaissance Orbiter
Phoenix
Phoenix descending by parachute, 2008, by the Mars Reconnaissance Orbiter
Phoenix's landing site, 2008, by the Mars Reconnaissance Orbiter
Phoenix as the ice melts in spring, 2010, by the Mars Reconnaissance Orbiter
Curiosity
Curiosity's heat shield, 2012, by Curiosity
Curiosity descending by parachute with heat shield falling away, 2012, by the Mars Reconnaissance Orbiter
Curiosity's landing site, 2012, by the Mars Reconnaissance Orbiter
Curiosity's tracks, 2012, by the Mars Reconnaissance Orbiter
Other Martians
Mars Odyssey in orbit, 2005, by the Mars Global Surveyor (also in orbit)
Mars Express in orbit, 2005, by the Mars Global Surveyor (also in orbit)
Sojourner, 1997, by the Mars Pathfinder lander
Mars Pathfinder (AKA Sagan Memorial Station), 2007, by the Mars Reconnaissance Orbiter
Viking 1, 2006, by the Mars Reconnaissance Orbiter
Viking 2, 2006, by the Mars Reconnaissance Orbiter
Beagle 2, 2014, by the Mars Reconnaissance Orbiter
Schiaparelli crash site, with insets of its heat shields, 2016, by the Mars Reconnaissance Orbiter
Not Mars
Sojourner 3, by (the crew of) Apollo 12 (as seen in the background)
Rosetta, by its lander Philae, before separation
Rosetta, by its lander Philae, just after separation
Philae, by its mothership Rosetta, just after separation
Philae, by its mothership Rosetta, after bouncing off a comet