It will be the first time since the retirement of the space shuttles in July 2011 that NASA astronauts launch from American soil on an American rocket to the International Space Station. And unlike for astronaut launches in the past, when NASA ran the show, this time SpaceX will be in charge of mission control.
Here’s what you need to know about the launch.
When is the launch and how can I watch it?
The launch will take off from Kennedy Space Center in Florida at 4:33 p.m. Eastern time.
Is the weather looking good?
It’s not terrific. On Tuesday, the forecast from the Department of Defense’s 45th Weather Squadron gave a 60 percent chance that the weather would be good enough at the launchpad to blast off. But because people are flying to space, the weather has to be good in two places: at the launch site and in the long swath of ocean — along the East Coast and then across the North Atlantic to nearly Ireland — where the astronauts might splash down in an emergency.
If the launch is postponed, SpaceX and NASA can try again on Saturday or Sunday.
Who is blasting off today?
The astronauts are Robert L. Behnken and Douglas G. Hurley, whom NASA selected to be astronauts in 2000.
They have each flown twice previously to orbit on space shuttle missions, although this is the first time they have worked together on a mission.
What are they flying in?
SpaceX has never taken people to space before. Its Crew Dragon is a gumdrop-shape capsule — an upgraded version of SpaceX’s original Dragon capsule that has been used many times to carry cargo, but not people, to the space station.
It has space for up to seven people, but will have only four seats for NASA missions. If this launch succeeds, later in the year it is to ferry four astronauts to the space station.
When will the astronauts arrive at the space station?
The Crew Dragon is to arrive at the International Space Station 19 hours after launch, shortly before noon Eastern time on Thursday. During that time, the astronauts will test flying the spacecraft and verify that the systems are performing as designed.