SpaceX set to launch critical Dragon demonstration mission tonight

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  A pretty day at Kennedy Space Center on Friday, as remote cameras were set up. [credit: Trevor Mahlmann for Ars Technica. ]

It's finally go time. For the first time since 2011 and the space shuttle's retirement, a rocket and spacecraft stand on a launch pad in Florida capable of blasting humans into space. Launch time is set for 2:49am ET (07:49 UTC) Saturday from Kennedy Space Center. NASA and SpaceX have worked toward this goal for nine years. It hasn't always been easy, but now here we are.

This particular Dragon won't carry humans, just a single mannequin named Ripley as an homage to Sigourney Weaver's iconic character in the movie Alien. Ripley will wear a flight suit and be well instrumented in order to determine conditions inside the spacecraft. "The idea is to get an idea of how humans would feel in her place basically," Hans Koenigsmann, the vice president of build and flight reliability at SpaceX, said at a news briefing Thursday.

Critical flight

NASA is taking few chances for this critical flight. Although SpaceX has flown a cargo version of the Dragon spacecraft to the International Space Station since 2012, the crew variant of the spacecraft is entirely made over from the exterior solar panels to the interior life support system. When Dragon arrives at the space station, which it will on Sunday morning if the launch proceeds as scheduled, crew there will enter the vehicle with full oxygen masks. This is because Dragon's cooling system relies on freon, and there's presently no robust way to check for leaks.