In late 2003 and early 2004, the surface of Mars will be invaded by not just one but three mechanical ambassadors from Earth. The Beagle 2 lander, the United Kingdom’s contribution to the European Mars Express mission, is set to land on Mars in December, 2003. NASA’s two spacecraft will follow close behind. Mars Exploration Rover One (MER 1) is scheduled to arrive at the red planet on January 4, 2004. Its twin, MER 2, is scheduled for landing on February 8, 2004. Deciding exactly where these spacecraft will land has provided some interesting challenges.