Last week NASA released images of astronauts testing out SpaceX’s sleek, white and gray spacesuits.

Since NASA shuttered its space shuttle program in 2011, astronauts have hitched rides to the International Space Station on spacecraft launched from Russia. Now, the space agency is preparing to once again send astronauts into space aboard American rockets, likely in 2020 as part of its commercial crew collaboration with private companies SpaceX and Boeing. But unlike space shuttle crews of the past, the newest astronauts won’t be wearing those spiffy orange flight suits.

Astronauts Bob Behnken and Doug Hurley donned their new suits at a SpaceX facility in Hawthorne, California, as part of a training session for the Demo-2 mission, the first crewed SpaceX flight to the International Space Station. The training was essentially a dry run for the astronauts and ground crew to go through all the procedures of launch day, when Behnken and Hurley will ride a Crew Dragon spacecraft that launches into orbit on a Falcon 9 rocket from NASA's Kennedy Space Center in Florida.

The practice procedures included a crew suit-up, in which suit engineers helped the astronauts put on their one-piece space duds, then went through the leak check procedure and helped them buckle into their seats.

Chelsea Gohd at Space.com reports that when SpaceX founder Elon Musk debuted the suit design on Instagram in 2017, the response to the sleek, futuristic looking suit was fairly positive. The spacesuit was designed by Hollywood costume designer Jose Fernandez, who created the superhero costumes for Wonder Woman, Wolverine and Captain America: Civil War.

SpaceX has not released details on the features of the space onesies, but Gohd reports it is likely similar to previous NASA flight suits that included liquid-cooling systems, emergency breathing systems, automatic parachutes, food and water and could also pressurize in an emergency situation.

Astronauts, however, will not just be wearing black and gray into orbit. Missions conducted using Boeing’s Starliner launch system will have their own bright blue spacesuits, which were released in 2017. In a press release, NASA reports those suits weigh about 20 pounds and have the helmet and visor built into the suit instead of being detachable. The gloves are designed to work with touchscreens. The suit has vents to keep the astronauts cool and to allow for instant pressurizing.

Hopefully, astronauts won’t have to rely on their flight suits much at all. “The spacesuit acts as the emergency backup to the spacecraft’s redundant life support systems,” says Richard Watson, subsystem manager for spacesuits for NASA's Commercial Crew Program. “If everything goes perfectly on a mission, then you don't need a spacesuit. It’s like having a fire extinguisher close by in the cockpit. You need it to be effective if it is needed.”

These flight suits, however, aren’t designed to let astronauts float out in space. Those extravehicular activity (EVA) suits are a whole different engineering challenge. Last week, the companies ILC Dover and Collins Aerospace—both of which produced the current spacesuits used by space station astronauts to conduct space walks—unveiled a new upgraded prototype suit called Astro. The system includes an EVA suit, which has better mobility than previous versions and includes a digital display system as well as a life support backpack that attaches to the suit. It also includes a next-gen carbon dioxide scrubber, which will increase how long a user can wear the suit and may allow future astronauts to bounce around on the moon and Mars.