Starliner Ready to Come Home

Boeing’s Starliner capsule is two days away from returning to Earth after an eventful crewed flight test. NASA said today they will close the hatches tomorrow with undocking set for Friday afternoon. The weather is looking good for landing in New Mexico six hours later, but even if there is a delay for any reason, they will not be reopened until Starliner is back on terra firma. Helium leaks and thruster failures led NASA to decide to bring Starliner home empty instead of carrying the two NASA astronauts who were aboard when it launched.

After years of delays, the Starliner Crew Flight Test (CFT) lifted off from Cape Canaveral Space Force Station, FL on June 5. During the one-day trip to the International Space Station, five of the 28 Reaction Control System (RCS) thrusters did not perform as planned and four helium leaks were detected in addition to one discovered before launch.

Over the past two months, Boeing and NASA have been trying to figure out what happened. Tests on the ground and in space provided some answers, but also raised more questions. In the end, NASA decided not to risk the lives of the two NASA astronauts, Butch Wilmore and Suni Williams, because thruster performance was uncertain and they had an easy alternative — keep them on the ISS and make them part of the next regular crew exchange, bringing them back on SpaceX’s Crew Dragon in February.

Unlike previous eras where NASA only had one human-rated spacecraft — Mercury, Gemini, Apollo, and the space shuttle — NASA decided in 2014 that it wanted two dissimilar crew space transportation systems to take astronauts to and from the ISS so if anything went wrong with one it would have an alternative. The ISS has been permanently occupied by international crews rotating on regular schedules for almost 24 years and NASA plans to continue operating it at least until 2030.

NASA selected Boeing and SpaceX to build the new systems through Public-Private Partnerships where the government and the companies invest in development, but the companies retain ownership. NASA paid Boeing $4.2 billion and SpaceX $2.6 billion.  Once NASA certifies the systems as safe for NASA astronauts, it purchases transportation services under fixed price contracts. If there are cost overruns, the companies have to pay, not the government.

The companies are encouraged to find non-NASA customers to close the business case. SpaceX has done that. In addition to launching missions to the ISS for NASA every six months since 2020, it has launched four private astronaut missions so far with another waiting on the launch pad right now for the weather to cooperate.

Boeing is years behind SpaceX, however, and has had to spend $1.6 billion of its own money to fix problems that have arisen so far. It hoped this flight test would be the final step towards certification with operational flights beginning in February 2025, but that is not to be.

NASA decided during a Flight Readiness Review on August 24 to bring Starliner back to Earth empty because they are not comfortable that they understand how the thrusters will perform.

During a pre-departure news conference today, NASA Commercial Crew Program Manager Steve Stich and ISS Program Manager Dana Weigel conceded that Boeing-NASA tensions were high during that meeting. Stich called it a “tense technical discussion” while Weigel pointed out that the final decision on crew safety was NASA’s to make.

From a Boeing standpoint they certainly know their spacecraft and they’re analyzing risks and what they think the capability is with the Starliner vehicle. But Boeing is not in a position, and it would be unfair to ask them, a risk versus risk trade for the scenario that NASA was weighing, which was bringing [Butch and  Suni] home in the Starliner crewed or coming up with an alternate plan….

The agency is in a bit of a different position in terms of our understanding about the risks and what’s available to us without Starliner. … And even Boeing stated that as part of the review … acknowledging that that part is really in NASA’s hands in terms of making that trade.” — Dana Weigel

NASA decided to leave Butch and Suni aboard the ISS to become part of Crew-9, which is about to replace Crew-8 for the next six-month increment. Two of the four original members of Crew-9 will launch to the ISS on September 24 while the other two will have to wait for another opportunity so Butch and Suni can have their seats to return to Earth in February.

Butch and Suni are experienced NASA astronauts and Navy test pilots who have spent long-duration missions on the ISS already. There are plenty of supplies on the ISS and cargo spacecraft routinely deliver more.  Northrop Grumman’s NG-21 Cygnus is there right now and a SpaceX Cargo Dragon will launch next month.

As for Starliner, it will undock autonomously on Friday at 6:04 pm ET and land six hours later at 12:03 am ET in White Sands, New Mexico. Two uncrewed Starliner flight tests landed there in 2019 and 2022.

Starliner pushes away from the ISS using springs so NASA is not concerned about a collision. About 90 seconds later, forward-facing RCS thrusters will engage to move Starliner out and away from the ISS. The five thrusters that failed during docking were in the aft end of the Service Module and four of them quickly resumed operation. NASA doesn’t anticipate any problems departing the area around the ISS.

The thrusters and the helium leaks — thought to be caused by bad seals — are all in the Service Module, which does not return to Earth. That’s one of the reasons they’ve kept Starliner docked to the ISS these past two months so they could conduct tests while they could.

Now the RCS thrusters just have to put Starliner on the path back towards Earth and hold it in the right attitude while the larger Orbital Maneuvering and Attitude Control (OMAC) thrusters make the one-minute deorbit burn at 11:17 pm ET to put the Crew Module on the trajectory to White Sands. The two modules then will separate and the Service Module will burn up in the atmosphere.

Everything is set for Friday, but if weather or anything else gets in the way there are backup landing opportunities every four days.

How long it will take Boeing to fix Starliner is unknown, but NASA says the earliest it will fly again is August 2025.