Starliner’s Crew Flight Test Comes to an End

Boeing’s Starliner capsule undocked from the International Space Station at 6:04 pm ET Friday and landed in New Mexico six hours later just after midnight Saturday. That brings to an end the Crew Flight Test although the crew — NASA astronauts Butch Wilmore and Suni Williams — are not aboard. Concerns about Starliner’s thrusters led NASA to decide to leave them on the ISS and bring Starliner back to Earth empty.

The capsule, named Calypso, autonomously separated from the ISS.  Springs pushed it away initially and then Starliner’s Service Module Reaction Control System (RCS) thrusters fired 12 times to move it further away to begin the trip back to Earth.

#Starliner has undocked from the @Space_Station and will begin its journey back to Earth.@NASA and @BoeingSpace are targeting approx. 12am ET Sept. 7 for the landing and conclusion of the Crew Flight Test mission at the White Sands Space Harbor, New Mexico landing site. pic.twitter.com/uB0DgmUUPW

— NASA Commercial Crew (@Commercial_Crew) September 6, 2024

The rest of the six-hour reentry went according to plan with a 58 second deorbit burn at 11:17 pm ET using four of Starliner’s larger Orbital Maneuvering and Attitude Control (OMAC) thrusters.  After the burn the Service Module separated from the Crew Module and was put on a flight path to burn up in the atmosphere. The Crew Module continued back to Earth with touchdown at White Sands Space Harbor, part of the White Sands Missile Range in New Mexico, at 12:01 am ET on Saturday, September 7 (10:01 pm Friday local time). Infrared imagery from NASA aircraft showed the nighttime parachute deployment and landing.

NASA reported that all 12 RCS departure burns went fine. Those thrusters on the Service Module are the reason no one is aboard Starliner on this last leg of its journey, however.

Launched on June 5, Starliner arrived at the ISS exactly two months ago on June 6. During its approach, five of the 28 RCS thrusters in the Service Module didn’t operate because software “deselected” them. Starliner also experienced four helium leaks in addition to one discovered prior to launch.

Four of the thrusters later came back online, but ground- and space-based tests over the subsequent weeks left enough questions in NASA’s mind that they decided not to risk putting Butch and Suni onboard for the return trip. Instead they will become part of the next regular crew rotation, Crew-9, and return with them on SpaceX’s Crew Dragon in February.

What Boeing and NASA have determined so far is that overheating caused “poppet” seals in some of the aft thrusters to swell, restricting the flow of propellant. Boeing developed models to explain what happened and was confident the thrusters would be fine for reentry, but NASA didn’t agree.  Butch and Suni are NASA astronauts and it was NASA’s decision to make.

The Crew Module has 12 of its own RCS thrusters of a different design. NASA tested them when Starliner moved away from the ISS and one didn’t fire, but they are in two redundant strings of six so there was no effect on the landing.  Nonetheless, it is another thruster malfunction Boeing will have to investigate.

In an emailed post-landing statement, Mark Nappi, Boeing Vice President and Program Manager for Commercial Crew, said “I want to recognize the work the Starliner teams did to ensure a successful and safe undocking, deorbit, re-entry and landing” and Boeing “will review the data and determine the next steps for the program.”

In a separate message to Boeing Defense, Space and Security (BDS) employees, Ted Colbert and Kay Sears said “While this may not have been how we originally envisioned the test flight concluding, we support NASA’s decision for Starliner and are proud of how our team and spacecraft performed through this adjusted mission to safely return home uncrewed.” Colbert is President and CEO of the BDS business segment. Sears is Vice President and General Manager for Space, Intelligence & Wespons Systems within BDS. They added:

“In a journey, there are obstacles and unexpected challenges. It is during these moments that we discover our strength and capabilities. We are immensely proud of the way our team handled these hurdles with resilience and a steadfast focus on safety and quality.

“Thank you for your unwavering commitment to our shared vision. Let us move forward with a renewed determination.”  Ted Colbert and Kay Sears, BDS

Steve Stich, NASA’s Commercial Crew Program Manager, called it “an important test flight for NASA in setting us up for future missions on the Starliner system” and there “was a lot of valuable learning that will enable our long-term success. I want to commend the entire team for their hard work and dedication over the past three months.”

This is the third flight of Starliner, but the first with a crew — albeit one way. An uncrewed Orbital Flight Test (OFT) in 2019 experienced significant problems and Boeing decided to refly it before putting people on board.  It was two-and-a-half years before they were ready to try again. Orbital Flight Test-2 (OFT-2) went well  in 2022, but other problems arose after that and this Crew Flight Test was delayed until now.

Starliner is Boeing’s competitor to SpaceX’s Crew Dragon to ferry astronauts to and from the ISS every six months. NASA’s goal is to fly one Starliner and one Crew Dragon every year. It wants two dissimilar systems for redundancy and competition.

SpaceX has been launching crews for NASA since 2020, but Boeing is far behind. It hoped this flight would lead to NASA certification of Starliner and the beginning of operational flights in February 2025, but NASA has already said it will use a Crew Dragon for that rotation. The earliest Starliner will fly again is August 2025 and that’s only if Boeing can fix the problems and win NASA certification by then.

Starliner is being built as a Public-Private Partnership and Boeing, not the government, must pay for cost overruns. Boeing has spent $1.6 billion of its own money already.

 

This article has been updated.