There are theories abounding that this whole mission to mars thing is simply a setup for them to fail at, and when they do fail, due to lack of funding and being not the most efficient thiing ever to come out of the US, the Bush Administration will shut NASA down... The money then moves on to more "deserving" causes.
I don't know what to think about it, part of me wishes it to simply believe its just a conspiricy theory, but part of me does wonder...