Aww, I loved Mission to Mars a whole huggy bunch (and despised red planet). I always thought it managed to capture both the spirit and cost of exploration.
On dueling movies in general: It always amazes me that while big studios tend to try to one up each other like this, there's always those crappy smaller studios that get wind of those projects and make their own knock-offs whose sole purpose seems to be suckering in people at the video store. My mom rented that hercules straight-to-dvd knockoff three times thinking it was the one with the Rock.
What amazes me more, however, is when these attempts at copying produce something substantially better than the original. Too bad I can't think of an example, but I know it's happened.