Boeing Starliner has been a disaster. Here's everything that went wrong

NASA previously scheduled the Boeing Crew Flight Test to launch on May 6, but it called for a delay just two hours before lift-off to replace a pressure regulation valve on the Atlas V rocket’s liquid oxygen tank. Space agency contractor ValveTech warned of a potential disaster and called for the Starliner launch to be put on hold until the spacecraft was deemed safe.

The Boeing Crew Flight Test launch eventually took place on June 6. However, six of the spacecraft’s 28 thrusters unexpectedly stopped working during the Starliner’s approach to the International Space Station, forcing NASA to delay the return to determine what went wrong. Steve Stich, manager of NASA’s Commercial Crew Program, stated that the spacecraft could spend 45 days docked to the ISS.

NASA attempted to quell the unease around the Starliner’s extended stay docked to the ISS by reiterating the mission’s nature as a test flight and highlighting the spacecraft’s few strengths. The Starliner’s battery proved capable of reliably recharging, keeping the Boeing spacecraft in orbit beyond the 45-day limit.

NASA became publicly adamant that the Starliner was safe after rumors began circulating that the space agency was considering using a SpaceX Crew Dragon to bring the mission’s two astronauts back from the ISS. The space agency that Starliner was capable of returning to Earth if there was an emergency.

The lengthy Boeing Crew Flight Test wasn’t the first time the Boeing Starliner has experienced delays. NASA initially planned the mission for a 2017 launch. However, a never-ending string of development setbacks pushed the debut crew mission until 2024. The previous delays forced Boeing to overspend the Starliner’s budget by $1.5 billion.

As NASA contemplated letting Barry Wilmore and Suni Williams return on the Starliner, Boeing tossed another wrench into the works. The space agency feared a needed software update could brick an ISS docking port. Boeing had removed the autonomous undocking feature from the Starliner’s software package at some point before the mission.

NASA delayed the Boeing Starliner’s return for good reason. If the right combination of thrusters failed, the Starliner could be left drifting through space and potentially collide with the space station. The catastrophic impact was only one of many possibilities, but NASA understandably aims to minimize all potential risks.

The International Space Station doesn’t have any laundry facilities onboard, so Butch Wilmore and Suni Williams were forced to start rationing their clothes. The astronauts also filled their schedule by helping the station’s permanent contingent with small tasks, like repairing a urine processing pump.

Fresh laundry wasn’t the only clothing that NASA would have to launch up for the two stranded astronauts. Boeing’s intravehicular activity suits aren’t compatible with the SpaceX Crew Dragon. IVA suits are linked to spacecraft during re-entry to provide data to mission control. However, NASA didn’t require cross-compatible systems in the Commercial Crew Program bid.

NASA finally decided at the end of August that Wilmore and Williams wouldn’t return to Earth on the Boeing Starliner. The space agency slated the SpaceX Crew-9 mission to launch with two empty seats and two extra IVA suits to bring the stranded astronauts home. They only have to wait until 2025.

While engineers focused on the issues with the Starliner’s thrusts, Butch Wilmore discovered a new mystery that was personally frustrating. Wilmore recorded an unexplained noise from the module’s speakers that sounded similar to a sonar ping.

Once the return date was announced, NASA outlined the unique breakout burn procedure that the Starliner would use to mitigate its thruster problems. The breakout consisted of a dozen short and sharp thruster burns. The space agency also explained the problem’s specifics. The Teflon coating over a thrust valve would heat up, melt, and be extruded from the jet. The obstruction would block the propellant flow.

The Starliner Calypso finally undocked from the ISS just after 6:00 p.m. EDT last Friday, then landed at White Sands Test Facility in New Mexico six hours later. Boeing would need to resolve the melting Teflon problem if the Starliner ever hopes to return to orbit.

New technical problems that cropped up during the Starliner’s autonomous return justified NASA’s decision to fly the spacecraft back without Wilmore and Williams. A new thruster failed on the Boeing spacecraft. Also, the Starliner experienced a temporary blackout of its guidance system during reentry. Yet, Boeing suggested that the astronauts return onboard.

A version of this article originally appeared on Jalopnik.