If they die, they'll be freeze-dried in a body bag. And if they survive, they'll have to re-enter Earth's atmosphere at a screaming 8.8 miles (14.2 kilometers) per second.

Speaking at the National Space Symposium here, members of the Inspiration Mars Foundation described the challenges inherent in launching two humans on a 501-day flyby journey to the Red Planet and back in January 2018, but remained optimistic that those challenges aren't insurmountable.

 

"So far, we haven't come up with any show-stoppers, so that's exciting," said Jane Poynter, president of the Paragon Space Development Corp., which has partnered with Inspiration Mars.

 

Millionaire Dennis Tito, who became the first space tourist in 2001, unveiled Inspiration Mars' "Mission for America" in February.