Boeing’s Starliner capsule sits atop a United Launch Alliance Atlas V rocketNASA/Kim Shiflett

Boeing is set to launch its Starliner astronaut capsule to the International Space Station (ISS) as soon as Wednesday, more than a year and a half after its first orbital Starliner test failed to reach the station and returned home earlier than planned. The mission is a test, and there won’t be any humans on board. Originally slated to launch on July 30th, Boeing and NASA have delayed the launch date twice so far, the first delay due to a mishap at the International Space Station and the second due to an issue that Boeing has yet to clarify.

If all goes well, it’ll mark a crucial step toward Boeing and NASA’s goal to use Starliner for routine astronaut missions, and a key chance to salvage the aerospace giant’s reputation after years of setbacks and controversies.

The test mission, called Orbital Flight Test 2, will launch from Florida’s Cape Canaveral Space Force Station using an Atlas-V rocket built by United Launch Alliance. Starliner, sitting on top of the rocket, will do what Boeing’s rival SpaceX did with its Crew Dragon capsule in early 2019 — go to space, dock to the ISS, remain there for 10 days, then return back to Earth. Both companies have developed their capsules under NASA’s Commercial Crew Program, with Boeing’s Starliner contract at $4.5 billion and SpaceX’s at $2.7 billion.

Starliner, a seven-seated astronaut pod shaped like a flat acorn, suffered a series of software glitches during its 2019 test flight, forcing Boeing to skip its space station docking and bring it home early just two days after launching to space. In the next 18 months, Boeing worked to settle 80 different concerns that sprang from lengthy technical investigations led by company employees and independent experts at NASA. Those 80 recommendations have been implemented, Boeing’s Starliner chief John Vollmer told reporters on Tuesday, and Starliner is ready to fly again.

What time is the launch?

Liftoff could be Wednesday at 1PM ET, the next launch opportunity after Tuesday’s delay. That delay, tweeted by Boeing Tuesday morning roughly three hours before a planned 1:20PM liftoff, was caused by a technical issue with Starliner, but it’s unclear how severe that issue is and the company has yet to provide more details on the matter. Tory Bruno, the CEO of ULA (the company launching Starliner to space), said mission teams will try to launch tomorrow.

Forecasts from the Air Force predicted only a 50 percent chance of favorable launch weather — odds that usually keep mission teams optimistic for a liftoff. Boeing and NASA postponed the mission from last Friday after a new Russian science module that docked the day before Starliner’s planned launch started uncontrollably firing its thrusters and pushed the entire space station out of position. NASA’s ISS team needed time to make sure everything on the space station was back to normal before welcoming a new spacecraft.

Whenever Starliner launches, it’ll try docking to the International Space Station roughly 24 hours later to begin its ten-day stay. NASA astronauts already on board the station — Shane Kimbrough, Megan McArthur, Mark Vande Hei — will run tests inside the capsule before it undocks roughly 10 days later. The exact time Starliner undocks to begin its trek home depends on weather forecasts over New Mexico, where the capsule will return.

How to watch Starliner’s mission

Like all of its launches, NASA plans to stream Starliner’s launch on a YouTube feed, with live coverage startingroughly an hour before liftoff. NASA’s live coverage of Starliner’s ISS docking begins the following day a few hours beforehand, and will also be viewable on the agency’s main live YouTube feed.

Update Tuesday, 11:00AM ET: Added update from Boeing that Starliner’s Tuesday launch has been postponed to Wednesday.