Boeing’s Starliner crew capsule, which has been plagued by years of setbacks and cost overruns amounting to roughly $1.5 billion, is about to take its first flight with humans on board. Boeing was chosen 10 years ago alongside SpaceX to develop a spacecraft that could ferry astronauts from US soil to the International Space Station (ISS), thus allowing NASA to end its reliance on Russia for crewed flights. The companies were each awarded a fixed-price contract under NASA’s Commercial Crew Program: $4.2 billion to Boeing for its CST-100 (Starliner) and $2.6 billion for SpaceX’s Crew Dragon.

Their initial deadline of 2017 proved to be a bit too ambitious. SpaceX managed its first crewed flight in 2020 — and about a dozen since — while Boeing has struggled to get its Starliner capsule off the ground. But as soon as May 6, it’ll finally have a crewed flight under its belt.

Starliner is now at Cape Canaveral Space Force Station’s Launch Complex-41 attached to the ULA Atlas V rocket that’ll send it on its way to the ISS. Liftoff is planned for 10:34PM ET on Monday, May 6. The capsule will be carrying two NASA astronauts: Butch Wilmore, the mission’s commander, and Suni Williams, who will serve as pilot.

NASA

Not only is it Starliner’s first crewed flight, but this test is only its third flight ever. The spacecraft (without anyone aboard) successfully demonstrated its ability to reach, dock and undock from the ISS in spring 2022 when it conducted its second Orbital Flight Test. On its previous attempt, in 2019, Starliner failed to make it all the way to the ISS thanks to a software issue that resulted in it burning too much fuel (one of a few problems Boeing missed after it opted at the time not to do end-to-end testing).

It’s suffered numerous other problems, too, in the years since Boeing bagged the NASA contract, causing the company to slip far behind SpaceX. There was a toxic fuel leak during a 2018 test. Then corrosion caused valves in the propulsion system to stick, waylaying Boeing’s plans for a 2021 launch, as Ars Technica reported earlier this year. Problems with the spacecraft’s parachute deployment system derailed plans for a launch last summer, and the team had to remove around a mile of flammable tape.

Boeing has also had its fair share of troubles beyond Starliner during this time, facing increased scrutiny into the safety of its airplanes — particularly the 737 Max line — after two fatal crashes in 2018 and 2019, on top of other less serious incidents. Most recently, a panel blew off a 737 Max 9 mid-flight in January, forcing it to make an emergency landing.

The May 6 flight marks a major step toward Starliner’s certification as a crew transport system that NASA can actually put into its rotation for trips to the ISS. That will give the space agency the redundancy it’s looking for; with both Crew Dragon and Starliner in operation, it’ll always have a backup option in case something happens to one of them. Both NASA and Boeing have been adamant that the capsule has been put through an exhaustive review process and is ready to support astronauts. NASA wrapped up its Crew Flight Test Readiness Review of Starliner on April 25.

“The first crewed flight of a new spacecraft is an absolutely critical milestone,” NASA associate administrator Jim Free said during a briefing on the completion of the review. “The lives of our crewmembers Suni Williams and Butch Wilmore are at stake — we don’t take that lightly at all.” The latest review is “the culmination of a detailed review season that has really thoroughly established that we are really ready to go on this flight,” said NASA chief flight director Emily Nelson.

NASA/Frank Michaux

It’s expected to take about 24 hours for Starliner to reach the ISS after it lifts off, and as this is a test flight, its onboard crew will have a lengthy task list of systems and equipment checks to complete across every phase of the journey. While Starliner can operate autonomously, the crew will test its manual controls and make sure it’s in good shape for manual abort scenarios. After Starliner docks to the space station, the astronauts will spend about a week there working with the current crew, Expedition 71.

Then, they’ll undock from the orbiting lab and head home — and put Starliner through the test of reentry and landing. A few potential landing sites in the southwest US have been picked out, including the White Sands Missile Range in New Mexico.

Wilmore and Williams have been training for Starliner’s first flight for years. “They know the vehicle inside and out, and they’ve been part of the test environment that’s developed the Starliner capability,” said Steve Stich, manager for NASA’s Commercial Crew Program. All involved in last Thursday’s briefing acknowledged that they may encounter some unexpected challenges, and that there’s much to be learned from this first crewed flight. “It’s a good reminder for all of us that the team has practiced, run sims, run models, but there’s nothing like flying in the space environment,” said Free.

The NASA and Boeing officials also expressed their confidence that the craft itself and the teams handling its journey are well-prepared for the job. The astronauts echoed these sentiments upon arriving at the Kennedy Space Center in Florida. “We wouldn’t be here if it weren’t ready,” Wilmore said, addressing questions from the press. “We are ready, the spacecraft’s ready, and the teams are ready.”

If Starliner for whatever reason can’t launch on the 6th, it’ll have backup opportunities on May 7, 10 and 11. After the Crew Flight Test is complete and the astronauts are back home, NASA will get to work certifying the spacecraft for future missions bringing crews to and from the ISS. It’s currently targeting 2025 for Starliner to begin duty.

“I don’t want to get too far ahead because we still need to fly a successful mission,” said Free ahead of Starliner’s launch, “but when we do, and when we certify Starliner, the United States will have two unique human space transportations that provide critical redundancies for ISS access.”