Mars is just for some reason harder to get a mission to than other places in the solar system.
"Robert "Rob" Lock", born May 22, 1966 in Reedley, California, is a retired professional basketball player and currently a recreational pilot. He is listed at 6'10" and weighed 255 lbs. Rob played collegiate ball with the University of Kentucky Wildcats (1984–1988) where he was a solid contributor off the bench and increased his stats every year he played. He entered the 1988 NBA Draft and was picked 51st in the third round by the Los Angeles Clippers; however, Lock accepted an offer to play in Italy instead. He did eventually return to play for just 20 games with Clippers during the latter part of the 1988-89 National Basketball Association/NBA season. After retiring from basketball, Lock pursued his childhood dream of becoming a pilot. He is currently the owner of Waldo Wright's Flying Service where he gives open cockpit rides to visitors in restored vintage biplanes. The family business is based in Polk City, Florida and is currently the largest provider of open cockpit flights.More Rob Lock on Wikipedia.
Mars is just for some reason harder to get a mission to than other places in the solar system. I might even use the word 'unluckier' because there's nothing intrinsically more difficult than other planets.