Boeing’s Starliner capsule returns home without its crew

Ever since the Starliner capsule departed the ISS, it’s been slowly moving away from the space station.

While the spacecraft has been drifting away, flight controllers have taken the opportunity to run some tests on the vehicle’s propulsion systems.

According to NASA’s live stream, one of the Starliner’s reaction control system (RCS) thrusters did not function. That’s not a big deal, NASA and Boeing commentators said, because there are plenty of backup RCS thrusters to use on the capsule.

But previously, NASA and Boeing officials said at least one RCS thruster located just below the Starliner crew cabin — on the capsule’s service module — had also petered out and wouldn’t be used for the rest of the mission.

Webcast commentators also said that flight controllers tested 10 of the 28 RCS thrusters on the service module and “all performed as expected.”

NASA and Boeing officials in charge of making a final decision gave the final “go” to allow Starliner to make its return to Earth.

The deoribt burn lasts a few minutes and orients the spacecraft into a proper position for reentry. Earth’s thick atmosphere will do a number on the vehicle — so precise orientation will be key.

NASA has restarted its webcast of Starliner’s trip back home.

Teams on the ground are getting ready to make a final decision on whether to give the spacecraft a final “go” to conduct a firing of its thrusters that will plunge the vehicle back toward Earth.

Hosting tonight’s live stream for the space agency are NASA public affairs specialist Brandi Dean and Boeing’s Lauren Brennecke.

Boeing Starliner is shown docked to the International Space Station in May 2022 during the Orbital Flight Test 2 mission.

Even if Starliner’s uncrewed return trip Friday night goes well, NASA will still face a crucial decision on whether to grant the spacecraft its human spaceflight certification.

If something goes awry — or the spacecraft is denied certification — it would mark yet another blow to Boeing’s already deeply damaged reputation.

The Starliner program has had significant setbacks before. An uncrewed test flight to space in 2019 failed because of software issues, including an internal clock that was off by 11 hours.

That test mission had to be redone in 2022, but not before engineers had to address issues with sticky valves that prevented the spacecraft from taking flight earlier.

The barrage of problems throughout Starliner’s development has triggered recurrent rumors that Boeing may ditch the program all together.

Boeing’s new CEO Kelly Ortberg alluded to his conversations with NASA in an email to employees that was shared with CNN on August 30, saying:

NASA took a break from its live coverage of the Starliner return after the vehicle safely disembarked from the space station.

For the past few hours, the spacecraft has been coasting through orbit, waiting to make its dangerous plunge back into the thick of Earth’s atmosphere.

The space agency is expected to resume its webcast of the event at 10:50 p.m. ET, taking viewers through the final milestones of Starliner’s descent back to Earth.

Butch Wilmore and Suni Williams couldn’t come home on Starliner today.

And Dana Weigel, the manager of the International Space Station at NASA’s Johnson Space Center in Houston, noted during a news conference on Wednesday that Williams and Wilmore have already adopted the type of workout routines required of astronauts who stay in space for months at a time — even though Wilmore and Williams were only expecting to stay a week or so.

Such workouts are essential for human bodies: Floating around in the microgravity environment of space can lead to bone and muscle deterioration.

Just to be clear, Wilmore and Williams aren’t strangers to such conditioning. They’ve both completed long-duration stays in space before.

And Williams, for the record, has already proven her chops as a standout space athlete.

In 2012, during an earlier trip to the International Space Station, she became the first person to finish a triathlon in space. Williams used a stationary bike, simulated swimming with a weightlifting machine and ran on a treadmill while strapped in by a harness so she wouldn’t float away.

That feat came after she ran along with the Boston Marathon from the space station in 2007.

Williams and Wilmore logged a combined total of 500 days in space before launching on the Starliner test flight. Williams even said that she cried after she left the space station following her last mission in 2012, unsure if she would ever return.

“This flight is a dream for her,” one NASA commentator said during a June 5 livestream of the Starliner launch.

NASA astronauts Stephanie Wilson, left, and Zena Cardman.

NASA ultimately decided it was too risky to fly Starliner home with its crew — astronauts Suni Williams and Butch Wilmore — on board, so the duo will return to Earth aboard a SpaceX Crew Dragon capsule instead.

The Crew Dragon spacecraft —unlike Starliner — has been certified to fly astronaut missions for about four years and has made around a dozen crewed trips to orbit. All of those trips have gone off without major issues.

The Starliner crew will take on new assignments as members of a Crew Dragon mission called Crew-9, which hasn’t even launched yet to the International Space Station. And the mission won’t conclude and return home from the orbiting laboratory until 2025.

In order to make room for Williams and Wilmore on Crew-9’s return trip, NASA had to boot two astronauts who had already trained for the mission.

The space agency announced last Friday that those two astronauts would be spaceflight veteran Stephanie Wilson and Zena Cardman, a marine scientist who was set to make her first trip to space and serve as Crew-9 mission commander.

Aleksandr Gorbunov, a Russian cosmonaut who got his seat via a ridesharing agreement between NASA and Russia’s space agency, Roscosmos, will remain on the flight. Cardman will also hand over commander duties to Nick Hague, who was previously named as the pilot for Crew-9.

An image from July 3 shows Boeing's Starliner spacecraft docked at the International Space Station.

That’s a big question looming over the mission.

If Boeing wants the Starliner capsule to start making routine trips to the International Space Station, the company needs to secure official human spaceflight certification from NASA.

This crewed test flight was expected to be one of the final milestones that would demonstrate Starliner’s spaceworthiness and clear it to ferry astronauts from NASA and its partner agencies to and from the orbiting lab on missions that would generate revenue for the beleaguered aerospace giant.

But now, given Starliner’s mechanical issues, everything seems up in the air.

There are some key reasons the US space agency wanted to have mission astronauts Suni Williams and Butch Wilmore on board the Starliner spacecraft during its trip home, according to Steve Stich, manager of NASA’s Commercial Crew Program.

NASA was aiming to make important evaluations, including the following assessments:

“This is part of the certification. It’s part of finishing the mission,” Stich said at a July 25 news conference.

When asked directly, however, whether NASA would require that Starliner make a trip home with crew on board before granting certification — or if it’s just something NASA would like to see happen — Stich did not give a direct answer.

Boeing’s Starliner spacecraft is pictured here in May 2024 on the launchpad at Cape Canaveral Space Force Station in Florida.

The final leg of Starliner’s test flight might not be playing out how everyone envisioned.

During an August 24 news briefing, NASA officials indicated that Boeing was not exactly on the same page when it came to some of the federal space agency’s risk assessments. 

Ken Bowersox, associate administrator for NASA’s Space Operations Mission Directorate, added, however, that Boeing had left the final decision up to the space agency “because of our wider view of all the risks involved.” 

While Boeing had said as recently as August 2 that its “confidence remains high” that Starliner can return with crew, since NASA announced its decision to fly the capsule home without crew, Boeing has said only that it is focused on “executing the mission as determined by NASA, and we are preparing the spacecraft for a safe and successful uncrewed return.”

NASA would not let astronauts fly home on Starliner.

So what exactly will Butch Wilmore and Suni Williams do while they’re stuck on the ISS for the next few months?

Currently, the two are guests. They’re not part of Expedition 71, the international crew of seven astronauts serving as the space station’s official staff.

But soon, they will transition into full-time expedition crew members — joining SpaceX’s Crew-9 astronauts, who are slated to launch on their mission as soon as September 24.

As part of Crew-9 and the formal ISS expedition, Williams and Wilmore will take up typical crew tasks, such as conducting spacewalks outside the space station, maintaining the orbiting laboratory and carrying out a tight schedule of science experiments.

They’ve actually already taken up some of that work.

And NASA previously confirmed the Starliner astronauts are prepared to make such a shift. The space agency had the foresight to train them for a monthslong mission to orbit for this test flight, even though it was originally expected to last just one week.

“Butch and Suni are fully trained,” Weigel added. “They’re capable and current with EVA (spacewalks), with robotics, with all the things we need them to do.”

That’s been a big point of contention among NASA, Boeing and journalists.

News outlets have described Starliner crew members Suni Williams and Butch Wilmore as being “stuck” or “stranded.” But the space agency and Boeing have repeatedly said those are not the words they would use to describe the astronauts’ situation.

The Starliner spacecraft has always been cleared to bring Williams and Wilmore home in case of an emergency — such as a piece of space debris striking the ISS and rendering the orbiting laboratory unsafe for any astronauts to live on board, NASA and Boeing officials have said.

But, because the Starliner wasn’t deemed safe enough to bring Wilmore and Williams home under normal circumstances, they will have to spend another five or six months on the ISS now that Starliner is flying home without them.

Steve Stich, NASA’s commercial crew program manager, spoke to this topic on Wednesday when asked at a news conference:

Boeing's Starliner spacecraft approaches the International Space Station on June 6, 2024.

The problems that have troubled Starliner are not simple. It is, after all, rocket science.

But NASA and Boeing have worked for weeks to better understand what went wrong.

First — during the first leg of Starliner’s trip to the International Space Station in June — a series of helium leaks sprang up.

Helium, for the record, is used to pressurize propulsion systems on the vehicle that help Starliner stay oriented in space.

Separately, five of Starliner’s 28 “reaction control system” (RCS) thrusters abruptly stopped working en route to the ISS. Four were recovered, but at least one will remain out of service for the rest of the mission. 

After weeks of testing, data review and analysis, NASA and Boeing said in late July that they believed they may understand the underlying issues.

The “doghouses,” or structures attached to the Starliner that contain propulsion equipment, were flying hotter than expected, causing some Teflon seals within the thruster systems to bulge — restricting the flow of propellant and causing the RCS thruster outages.

Separately, the helium leaks may have been caused by seals that became degraded by exposure to propellant vapor. 

Determining a root cause, however, is not a perfect science.  

And even if the issues were well understood, the Starliner team was faced with the fact that it would never get to look at the propulsion system on the actual Starliner vehicle in space.

It was impossible to visually inspect as the spacecraft sat attached to the International Space Station’s exterior.

And the unit that houses the troubled RCS thrusters and the helium leaks — called the service module — is not designed to survive Starliner’s trip home.

Instead, the service module, which is a cylindrical attachment at the bottom of the crew cabin, is meant to be ejected and disposed of on the way back to Earth. 

That’s a big reason why NASA and Boeing left the vehicle attached to the ISS for so long. It gave Boeing and NASA their only chance to run whatever tests they could on the service module before it was destroyed during reentry.

Atlas Blowout

Technicians and engineers prepare Boeing's Starliner for transport to the company's testing facilities at Kennedy Space Center in Florida in November 2018.

It’s not a great look for Boeing to bring Starliner home empty. Making the optics even worse is the fact that the company will have to rely on SpaceX — its rival under NASA’s Commercial Crew Program — to get the test flight astronauts home.

NASA, however, has sought to make clear this scenario is by design, highlighting the logic behind the Commercial Crew Program.

Since Boeing and SpaceX each secured contracts in 2014 to build vehicles capable of replacing the space shuttle, the space agency has said it wanted both companies to have separate and fully functional spacecraft. That way, one vehicle could back up the other in case one was grounded by technical problems or other unforeseen issues.

“We’re in a kind of a new situation here in that we’ve got multiple options,” said Ken Bowersox, associate administrator for NASA’s Space Operations Mission Directorate, during an August 7 news conference. “That’s something that we’re going to have to deal with in the future — we could find ourselves in a situation where we need to bring a (SpaceX) Dragon crew or a (Russian) Soyuz crew back on a Starliner.

“That’s why we want multiple vehicles — so that we have that option,” Bowersox added.

Still, this Starliner mission is a sour note for Boeing. For context, NASA funded the development of Crew Dragon and Starliner at the same time 10 years ago, awarding SpaceX $2.6 billion and Boeing $4.2 billion.

Crew Dragon, however, has already been in operation for four years, while the Starliner program is hundreds of millions of dollars over budget and years behind schedule.

NASA astronauts Suni Williams, left, and Butch Wilmore pose at Kennedy Space Center in Florida on June 5 before boarding the Boeing Starliner spacecraft for the crew flight test launch.

It’s been about two months since the veteran astronauts helming the Starliner mission — NASA’s Suni Williams and Butch Wilmore — spoke to the public from the International Space Station.

During a July 10 news conference, when their spacecraft’s issues were already apparent, the two spoke favorably about the Starliner capsule that carried them to space — and they made no indication that the spacecraft’s issues had rattled their confidence.

“Launch was spectacular. I mean, truly amazing,” Wilmore said from the space station during the news briefing. “And then we got into (checkouts of) our operational capabilities … and the spacecraft performed unbelievably well.”

However, he also said he felt the thrust was “degraded” when several thrusters unexpectedly failed as the Starliner approached its docking port at the International Space Station on June 6.

“But thankfully, we had practiced, and we had gotten certified for manual control, and so we took over manual control for over an hour,” Wilmore added.

In addition to those thruster issues, Starliner experienced helium leaks on the first leg of the trip.

“This is a test flight — we were expecting to find some things,” Williams said, echoing comments she made before liftoff. “We are finding stuff, and we’re correcting it and making changes, making updates with our control team.”

On Friday night, however, Williams and Wilmore waved goodbye to the Starliner as it departed the space station without them. And the astronauts have not spoken publicly since that July conference.

NASA’s official International Space Station account on X, the social media platform formerly known as Twitter, has shared audio of one of the final exchanges that Starliner’s crew, astronauts Suni Williams and Butch Wilmore, had with mission control before the vehicle left the ISS — leaving Williams and Wilmore behind.

The dispatch can be heard here:

Live communications between ground controllers in Houston and the International Space Station can be heard via this webcast from NASA.

Starliner makes its way back to Earth from the International Space Station, as seen on the NASA livestream on September 6.

In some fantastic news for the Boeing Starliner team, the vehicle — flying without crew — was able to use its thrusters and on-board navigation software to leave the International Space Station without issue.

But NASA just shut down its live stream (for a while), and the Starliner will now have to spend several hours moving through orbit before it finally hits the ground, marking its long-overdue return home.

Here are a couple things that Starliner is expected to do before NASA restarts its live stream around 10:50 p.m. ET:

Boeing’s Starliner spacecraft has safely exited the direct vicinity of the International Space Station and the nine astronauts currently on board the orbiting laboratory.

The spacecraft — flying home without its two-person crew because of issues with its thrusters and helium leaks — unlatched from its docking port at 6:04 p.m. ET.

The Boeing Starliner 'Calypso' capsule is seen as it detaches from the International Space Station on Friday evening.

It completed 12 brief firings of its small engines to maneuver away from the ISS as the space station orbited about 260 miles above China.

NASA astronaut Suni Williams, who along with Butch Wilmore made up the Starliner crew during the spacecraft’s journey to the ISS, bid farewell to the vehicle one last time as it disembarked.

“OK. She’s on her way home,” Williams said as the Starliner drifted away. “Congratulations to the undock team.”

The spacecraft is completing its breakaway engine burns, moving away from the International Space Station, where the Starliner has been attached since early June.

Roughly 15 minutes after detaching from the ISS, the vehicle left what’s called the “approach ellipsoid.”

That’s an imaginary area around the ISS. When a spacecraft is outside that area, they “have to be on what we call a 24-hour, safe, free-drift trajectory, and that means the spacecraft would not cross over that imaginary line (of the approach ellipsoid) for at least 24 hours — even if it lost all maneuvering capabilities,” according to commentators on NASA’s webcast.

Starliner is firing small engines — called thrusters — and all appears to be going well.

NASA and Boeing specifically chose to use a series of breakout burns to get the vehicle away from the ISS because it has had thruster issues throughout this mission so far.

But there don’t appear to be any new issues today.

“We heard confirmation that all 12 burns in this series of breakout burn firings have completed, and they were all good burns,” one commentator said on NASA’s webcast.

NASA’s Rob Navias said the vehicle is on a “perfect trajectory.”

A view of Starliner exiting the International Space Station's "keep out zone," as seen on the NASA livestream on September 6.

The spacecraft is on the move — and it’s now left what is referred to as the International Space Station’s “keep out zone.”

That’s an area around the ISS extending about 200 meters.

Vehicles approaching or leaving the ISS keep-out sphere must have explicit permission to enter or exit the area, as it’s well within the immediate vicinity.

A view of Starliner undocking from the International Space Station, as seen on the NASA livestream on September 6.

Starliner’s 12 hooks have unclamped from the International Space Station while floating over central China — about 200 miles high.

The Boeing CST-100 Starliner spacecraft is lifted at Cape Canaveral Space Force Station in Florida ahead of a May 2022 test flight.

Starliner had some issues on its way to the space station in June.

And Boeing and NASA worked for weeks to understand those problems.

But what — exactly — is NASA afraid will happen?

The space agency’s Commercial Crew Program manager, Steve Stich, spoke to exactly that during an August 7 news conference.

But first, here’s a quick primer on some Starliner lingo:

Service module: This is the part of the Starliner spacecraft where helium leaks and thruster problems have occurred. The module is designed to detach from the crew cabin during its return to Earth, and it’s not designed to survive the trip home.

Doghouses: Compartments on the outside of the service module that house thrusters.

Reaction Control System jets: There are 28 of these thrusters on Starliner’s service module (and one likely won’t work at all during the return trip.) The RCS thrusters are used to orient Starliner while in space. Five malfunctioned on the way to the International Space Station in June.

Orbital Maneuvering and Attitude Control jets: There are 20 of these thrusters on Starliner’s service module. So far, none of them have malfunctioned. Each OMAC has about 17 times the thrust of an RCS jet. 

“For a (safe and normal) de-orbit burn, we fire 10 OMAC thrusters in each of the four doghouses, and then the RCS jets are just there to hold the orientation,” Stich said. 

But a bleak outcome could arise, Stich added, if OMAC thrusters began failing because of helium leaks.  

“The worst case would be some integrated failure mechanism between the helium leaks and the RCS thrusters,” Stich said. “Then, you could end up with some cases that aren’t easily controlled, and that’s really the more stressing cases that the team is worried about.”

A Starliner spacecraft has already visited the International Space Station once during an uncrewed mission, and the vehicle survived reentry — relying solely on its onboard computers for navigation — twice.

During a 2022 test flight, Starliner essentially backed away from the ISS, then went up and over the space station before conducting a departure burn that sent it back down below the orbiting laboratory.

That’s all part of a capability that NASA had asked Boeing to ensure that Starliner had: Flying the vehicle in a loop around the ISS before leaving allows the spacecraft to inspect that aging ISS’s exterior.

But Starliner will operate a bit differently during this trip home.

The vehicle will conduct a special “breakout burn,” or a maneuver in which Starliner fires its thrusters to move away from the ISS, after the spacecraft departs from its docking port.

Unlike the looping maneuver used in 2022, the Starliner will carry out a series of 12 very brief engine firings that will send the Starliner up and away from the space station.

That’s fewer burns than the last go, said NASA commercial crew program manager Steve Stich, and “really puts less stress on the thrusters” — which are the components onboard Starliner that are having issues.

“It really just takes about five minutes or so to actually execute that whole sequence,” Stich added.

NASA flight director Anthony Vareha also said:

The cameras are rolling in mission control, and NASA has started its first of two live streams covering tonight’s Starliner return ahead of the vehicle’s undocking, expected just after 6 p.m. ET.

Polls have confirmed the spacecraft is “go” for undocking.

Hosting the livestream are NASA public affairs specialists Anna Schneider and Rob Navias, as well as Lauren Brennecke from Boeing.

In a conversation with mission controllers in Houston Friday following the “go-no go poll” just after 5 p.m. ET., Butch Wilmore and Suni Williams — the two NASA astronauts who flew Starliner to the ISS back in June — wished the spacecraft luck on its long-awaited and unexpected journey home.

Wilmore, Williams and mission controllers all refer to the capsule as “Calypso” — the name Williams gave this specific Starliner vehicle years ago.

“It is time to bring Calypso home,” Williams said to mission control Friday evening. “You have got this. We have your backs, and you’ve got this. Bring her back to Earth.”

Wilmore chimed in to add: “Many years of great enjoyment — being involved with each other’s lives, and it’s been special. Bring it home.”

A view from the NASA livestream on September 6.

Just after 5 p.m. ET Friday, officials on the ground carried out what’s called a “go-no go poll.”

It’s a routine step before a spaceflight activity in which various experts on the ground give verbal confirmation that they believe a spacecraft is ready to fly.

In this case, mission controllers confirmed they believe Starliner is ready to go tonight.

There are, however, still opportunities for flight controllers to change course.

According to the latest timeline issued by NASA, for example, there will be one last weather briefing — to gut check whether skies will be clear enough for Starliner’s return — at 5:44 p.m. ET.

If undocking goes to plan, however, there will be yet another chance to alter Starliner’s path as it approaches Earth. A separate “go-no go poll” will be conducted for the spacecraft’s deorbit burn at 11:17 p.m. ET, according to the space agency.

All sorts of objects streak through the night sky on a regular basis — including satellites soaring through space a few hundred miles away and meteoroids flying through the air in a fiery blaze as they hit the Earth’s atmosphere. (Meteors cause the most visible “shooting star” phenomenon.)

Those looking spaceward tonight across a stretch of land that extends from Mexico’s Baja California to the Texas-New Mexico border, however, might just catch a glimpse of a special space spectacle.

According to NASA, onlookers across the path highlighted in the graphic above may be able to see Starliner streaking through the sky around 9:51 p.m. MT (11:51 p.m. ET).

Boeing’s Starliner spacecraft launches into space from Cape Canaveral Space Force Station in Florida on June 5.

Starliner has had a long — and rough — road to get to this moment.

After a decade of development and years of delays, optimism surrounded the liftoff of Boeing’s spacecraft on June 5, when it kicked off its first crewed test flight from Cape Canaveral Space Force Station in Florida.

But almost immediately, issues began to arise as the vehicle made its way to the International Space Station.

The spacecraft sprang several helium leaks. Then, thrusters that are used to keep the Starliner capsule oriented in space began flaming out. Five of 28 such thrusters malfunctioned, though four were later recovered.

NASA and Boeing engineers then spent weeks attempting to better understand the issues as the Starliner remained docked to the space station. With little else to do, Starliner’s crew — NASA astronauts Butch Wilmore and Suni Williams — helped out with tasks on board the orbiting laboratory.

Ultimately, the weeks of research into the leaks and propulsion hiccups and additional ground tests did reveal the possible root causes of the issues plaguing Starliner. In short, parts of the propulsion system were likely getting too hot or exposed to propellant vapor, causing some materials to bulge or corrode.

Still, that hypothesis didn’t do much to help Boeing and NASA officials understand exactly how damaged Wilmore and Williams’ Starliner spacecraft was. Nor did the finding provide any concrete answers on how great an impact the issues might have on the flight home.

Ultimately, on August 24 — nearly three months after Starliner’s arrival at the space station — NASA determined it would fly home without its crew, deeming the vehicle too risky to carry people.

Boeing's Starliner spacecraft is docked to the International Space Station on July 3, 2024. This long-duration photograph was taken at night from the orbital complex as it soared 258 miles above western China.

It’s finally time for the Starliner capsule to come home — and a good performance Friday night could be crucial for Boeing and its astronaut spacecraft program.

The vehicle is returning without the two astronauts — Suni Williams and Butch Wilmore — that it carried into space. NASA deemed the Starliner unsafe to carry humans on the return trip because of issues that cropped up during the first leg of the mission.

The Starliner is set to leave its docking port at the International Space Station around 6 p.m. ET Friday before spending about six hours traveling through orbit as it slowly makes its descent toward home. 

Close to midnight, the capsule will reach one of the most important and treacherous legs of its test flight: reentry. The milestone will require the Starliner to orient itself carefully as it plunges into the thickest part of Earth’s atmosphere while still traveling at orbital speeds — typically more than 17,000 miles per hour (about 27,400 kilometers per hour.) 

As with every spacecraft that returns from orbit, the pressure and friction will put immense strain on the vehicle. The process can heat up the spacecraft’s exterior to more than 3,000 degrees Fahrenheit (1,649 degrees Celsius).

Then, as the Starliner vehicle free-falls through the air, a set of parachutes — which Boeing redesigned and tested as recently as January — must safely slow the capsule down before it reaches terra firma.  

Here’s when and where to catch the action on Friday night (all times are approximate and subject to change):