From “NASA flooded with 400 ideas of how to further explore Mars” (MSNBC.com, , 5/25/2012), we learn that, hit with budget cuts, NASA asked scientists to come up with affordable ideas, and received 400 instead of the expected 200:
The MPPG will be guided in part by the goals laid out by the U.S. National Research Council’s Planetary Science Decadal Survey, which was released in 2011. The survey ranked a Mars sample-return mission as a top priority.
Obama has also charged NASA with getting astronauts to the vicinity of Mars by the mid-2030s.
That’s 18 years from now and tough to do without money, but there should be a good idea in there somewhere.
See also: Carbon from Mars not biological, study says