On Friday, NASA announced it was ordering another International Space Station-bound crew flight from SpaceX — making it the second such mission Elon Musk’s company will conduct for the space agency, and NASA’s fourth order from a commercial provider.

Since closing down the Space Shuttle program in 2011, NASA has been forced to cooperate with Russia and buy seats on Soyuz rocket launches in order to safely get American astronauts to the International Space Station. The plan to get our astronaut launches back to U.S. soil and make our space program independent again means that we’ll turn over transportation missions to the ISS (both cargo and crew) to U.S. spaceflight companies.

The new announcement means SpaceX and Boeing will each conduct two missions that will send U.S. astronauts to and from the ISS.

“A lifeboat for the space station.”

“The order of a second crew rotation mission from SpaceX, paired with the two ordered from Boeing will help ensure reliable access to the station on American spacecraft and rockets,” says Kathy Lueders, manager of NASA’s Commercial Crew Program. “These systems will ensure reliable U.S. crew rotation services to the station, and will serve as a lifeboat for the space station for up to seven months.”

Handing off crew missions to commercial providers doesn’t just mean NASA can focus more time and resources on scientific studies and a future mission to Mars; it also folds into the agency’s broader goal of handing over low Earth orbit (LEO) operations to the private sector.

A SpaceX pressure vessel undergoes a stress test.
A SpaceX pressure vessel undergoes a stress test.

Of course, there’s just one big obstacle in the way before Boeing and SpaceX can compete their ISS launches: they both need to actually prove they can do the job. Neither company has ever launched a human into space. NASA, however, is working hard with both to design, build, and test their crew vehicles and verify that Boeing’s CST Starliner and SpaceX’s Dragon spacecrafts will be certified by February 2018 and October 2017, respectively.

The Boeing CST-100 Starliner
The Boeing CST-100 Starliner

And that’s extremely critical timing because NASA does not have any seats on any future Russian launches past 2018. If it turns out neither company will be ready for crewed missions by 2019, NASA’s ISS plans will be in jeopardy.

Of course, both companies seem to be making very good progress. Friday’s announcement seems to be a vote of confidence in SpaceX on NASA’s part.

Photos via SpaceX, Boeing