NASA calculated how risky SpaceX's first launch of humans could be, and the astronauts flying the space mission say they're 'really comfortable' with those odds

SpaceX is preparing to fly its first humans to orbit aboard a new Crew Dragon spaceship.
The Demo-2 mission, as it's called, is a high-stakes test flight of astronauts Bob Behnken and Doug Hurley to the International Space Station.
The mission on Friday passed a critical NASA safety review , teeing up the astronauts to launch from Cape Canaveral, Florida, at 4:33 p.m. ET on Wednesday.
NASA told Business Insider it estimates there's a 1-in-276 chance the flight could be fatal and a 1-in-60 chance that some problem would cause the mission to fail (but not kill the crew).
Behnken said he and Hurley are "really comfortable" with the risks of their flight.

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SpaceX is about to launch its first people to orbit and, in the process, resurrect human spaceflight from America.
Though SpaceX's flight is experimental, the two astronauts slated to pilot it say they accept the risks and are ready to fly .
The rocket company, founded by Elon Musk in 2002, has worked for nearly a decade with NASA to design, build, and fly a new seven-seat spaceship called Crew Dragon. NASA's hope with more than $3.1 billion effort is to once again launch astronauts from US soil — an ability the agency lost in July 2011 when it retired its last space shuttle.
NASA picked seasoned astronauts Bob Behnken and Doug Hurley to pilot the mission, called Demo-2. If all goes according to plan, the duo should lift off atop a Falcon 9 rocket at 4:33 p.m. ET on Wednesday, May 27 from Kennedy Space Center, Florida.
The crew would then fly to the International Space Station (ISS), dock with the football field-size laboratory , and stay for up to 110 days before returning to Earth inside Crew Dragon.
But as NASA, SpaceX, and the astronauts themselves have made abundantly clear, Demo-2 is not only an experimental crewed test flight but the first of a brand-new spaceship in nearly 40 years. 
"We're going to stay hungry until Bob and Doug come home," Kathy Lueders , who manages the Commercial Crew Program for NASA, said during a press briefing on Friday. "Our teams are scouring and thinking of every single risk that's out there, and we've worked our butt off to buy down the ones we know of, and we'll continue to look — and continue to buy them down — until we bring them home."
On Saturday, NASA told Business Insider just how risky it currently believes the flight will be, sharing two key risk estimates that the crew's mission would fail or that they'd be killed.
The odds of mission failure is about 4.5 times higher than the odds of crew death

NASA's Commercial Crew Program requires providers like SpaceX and Boeing, which is also developing a new spaceship (called the CST-100 Starliner), to meet a raft of safety requirements before flying any astronauts.
Among that checklist, loss-of-crew (LOC)...