According to some estimates, a person who spends two consecutive years in space increases their chances of getting cancer during their lifetimes by about 2 percent. Other studies have suggested that spending long periods in zero gravity can cause other health problems—in Zubrin's Athena mission, he proposed that by spinning the capsule, artificial gravity could be created.
NASA says it will "continue discussions with Inspiration Mars to see how the agency might collaborate on mutually-beneficial activities that could complement NASA's human spaceflight, space technology and Mars exploration plans," but has no plans to do a Mars flyby mission of its own anytime soon.
In 2010, President Obama said he hopes that "by the mid 2030s," NASA will "send humans to orbit Mars and return them safely to Earth."
A representative with NASA said he could not confirm whether or not Zubrin had met with Goldin to discuss Athena, but that Zubrin is "a highly respected scientist."
Wiens says NASA "would not get anything from a simple human flyby mission except to prove we can go there," to which Zubrin says, "exactly."
"Conceivably, a person can say 'What's the point of a flyby mission,' and the point is to say 'Follow me, this can be done,'" Zubrin says. "It's fear holding NASA back. These are risky missions. If you want to be safe, stay on the ground."