"There is a certain amount of technical hubris involved in thinking we can just make the leap to going to a Mars mission now," Hanley said. "We have studied the risks involved of sending humans to Mars and it is about a one in three chance that we would lose the crew using today's technologies. We have a lot to learn about how do we get humans to Mars, give them a reasonable chance of mission success, reasonable chance of coming back alive. The only way we will do that is to use the moon as a proving ground."
Leestma agrees with Hanley's assessment.
"Mars is pie in the sky, but one of the primary reasons we are going back to the moon is to learn how to operate on a planet that isn't six months away," Leestma said.
Is it even necessary to send humans to Mars when it is so much cheaper and safer to send robots instead?
Neal Lane, a former science adviser in the Clinton administration who is now a senior fellow at Rice University's Baker Institute, says no one can even hazard a guess at how much a manned mission to Mars would cost, in financial -- or human -- terms.
"We have sent robots successfully and gotten a lot of information, but there are things that humans can do that robots can't," Lane said. "Humans can react in real time on the spot and synthesize information and analyze what they are seeing."
Mars, according to Lane, holds secrets that scientists would like to unlock.
"Was there water on Mars? Where there is water, there is the possibility of life forms," he said. "Is life only on Earth, or does it exist someplace else in our solar system and beyond?"