Boeing’s Starliner capsule’s return to Earth will be delayed by several days due to problems with the thrusters and the planned spacewalk.
NASA announced today (June 18) that Starliner will end its first human mission to the International Space Station (ISS) on June 26 at the earliest, nearly three weeks after its launch. It is scheduled to land at White Sands Space Harbor in New Mexico at 4:51 a.m. EDT (0851 GMT) that day. We’ll be streaming it live here on Space.com via NASA TV.
The two-astronaut mission, known as the Crew Flight Test (CFT), was originally scheduled to spend about a week on the ISS, but its departure from the ISS was greatly delayed. NASA and Boeing are using the extra time to continue evaluating the thruster problems that marred the Starliner’s first attempt to dock with the ISS on June 6. Additionally, a delayed spacewalk for ISS maintenance will now take place on June 24, two days before Starliner’s scheduled departure.
“We want to give our teams a little more time to look at the data, do some analysis and make sure we’re really ready to come home,” said Steve Stich, NASA’s commercial crew program manager, during a live teleconference with reporters today. The Starliner can disengage in an emergency, but otherwise testing is underway to learn more about the vehicle’s systems.
Related: Thruster malfunctions and helium leaks can’t stop Boeing Starliner astronauts’ test flight — but why do they happen?
Stich reiterated that five of the Starliner’s 28 reaction control rocket engines failed during the final phase of the rendezvous with the ISS on June 6, although four of them eventually came back online. (The Starliner succeeded in its second attempt to connect, which occurred a few hours later on June 6.) An evaluation of what happened is ongoing. As part of that effort, Boeing and members of NASA’s ground team conducted a heat test of the jet with the astronauts over the weekend, and after that, Stich said, everyone is “feeling very confident.”
One thruster was not fired during the test due to abnormally low pressure first observed during docking and will remain offline during return to Earth. (Canadarm2, a robotic arm on the space station, was also used to view the jets with a robotic camera, according to ISS program manager Dana Weigel, who also participated in the teleconference.)
Docking the CFT was slightly more complicated than the only other time the Starliner approached the ISS, which was during an uncrewed test flight in May 2022. That uncrewed mission, called Orbital Flight Test 2 (OFT-2), also faced problems with jets that interfered with docking.
But “meeting [for CFT] was a bit more demanding on the powertrain. In other words, it fired the jets a little more often,” Stich said. In addition, the teams are running hardware simulations at NASA’s Marshall Space Flight Center in Alabama to model the Starliner’s ongoing helium leaks.
A small helium leak in one of the Starliner’s Reaction Control System (RCS) nozzles was first discovered on the pad in early May after the launch attempt was called off due to a problem with a rocket valve in the United Launch Alliance Atlas V capsule.
Several new helium leaks appeared during the mission and a fault tree is being analyzed to determine what happened. Stich said the helium leaks and problems with the RCS jets appear to have different causes, while Mark Nappi, vice president and program manager of Boeing’s commercial crew program, said a review of the data continues to reveal more about what’s going on.
The helium leak on the launch pad was not an immediate safety concern, but further investigation by NASA and Boeing revealed a design vulnerability in the RCS system that could affect the Starliner’s return. Agency officials subsequently certified the new reentry mode after testing the idea on the ground in simulations with the CFT crew, veteran NASA astronauts Barry Wilmore and Suni Williams, both former U.S. Navy test pilots.
Wilmore and Williams tested various Starliner systems in orbit, and ground teams continued to analyze the data to better address problems with the nozzle and helium leakage.
Stich emphasized that in-orbit testing on Saturday (June 15) gave the team confidence that the Starliner was recovering. “Saturday was a big day of understanding that the helium leaks had gone down and also understanding that the jets had recovered and we could count on the jets for the rest of the flight,” he said.
Although an assessment of what’s going on is ongoing, he said the tone of the conversation has changed. “I think now we’re doing the normal business that we do, what are the contingencies that could happen.” [with] disconnection time frame? And when we get to how we handle each of these contingencies if something were to happen, and then look at the procedures that we have in place. Are we ready to execute them?”
The mission’s delayed return also includes the planned June 13 spacewalk, which was postponed due to a “spacesuit discomfort” issue during donning. NASA astronaut Matt Dominick, an ISS crew member experiencing discomfort, will not go outside during the rescheduled June 24 spacewalk to prevent it from happening again, Weigel said during a news conference today.
Weigel told Space.com that if the June 24 spacewalk is delayed again, the priority will be to disconnect the Starliner, and NASA astronauts Tracy Caldwell Dyson and Mike Barratt will wait until the Starliner leaves to conduct an extravehicular activity.
CFT is a development mission. During the launch and flight campaigns, Boeing and NASA emphasized that mission timelines are therefore changing greatly as the Starliner flies its first-ever mission with humans on board. Wilmore and Williams said much the same thing based on their experience with the US Navy flying complex aircraft.
“We’ve always said it’s a test flight and we’ll learn some things. So here we are,” Nappi said during today’s press conference. “We found that our helium system, while manageable. It still works as we designed it. So we need to find out.”
Nappi emphasized that the performance of most of the RCS thrusters is good and heading towards nominal values, while the helium leaks “show that they are stable and lower than what was measured. [before]The team is working to learn more about the Starliner while the service module, which provides most of the spacecraft’s fuel and power, is still attached to the spacecraft as it will be jettisoned just before landing.
“This is an opportunity to fully understand system performance without time or time pressure,” Nappi said. Aside from technical issues, the mission met 77 of the original 87 flight test objectives, he noted; the remaining 10 will be evaluated during stall and landing.
Related: NASA is considering the potential effects of a helium leak and more on the Boeing Starliner astronaut test flight
Starliner, along with SpaceX’s Dragon capsule, are tasked with sending agency-led crews to the ISS from American soil. (Russia also conducts and launches cosmonaut-led crews on its long-duration Soyuz spacecraft.) CFT aims to certify the Starliner for the first operational spin mission to the ISS, called Starliner-1, which is expected to launch in 2025.
Dragon and Starliner were first tasked in 2014 to send NASA astronauts aloft by 2017, but financial and technical issues pushed the timeline back several years. SpaceX, whose Crew Dragon spacecraft is based on the ISS cargo capsule, launched its first astronaut test mission in 2020 after a single unmanned test flight. Starliner’s first human mission came four years later and required two unmanned tests, in part because the spacecraft has a new design.
The Starliner’s journey to the CFT was delayed after the capsule experienced problems on its first unmanned test mission in December 2019 and failed to reach the ISS as scheduled. (Astronauts often say, however, that timelines are difficult to estimate in development programs like Starliner because something unexpected can always happen.)
Boeing has been addressing these issues, which has taken time. The outbreak of the coronavirus pandemic in early 2020 further delayed the launch of the second unmanned ISS mission to May 2022. The next CFT launch was expected in 2023, but the flight was delayed after problems with parachute loading and flammable tape were discovered. last year.
The CFT then underwent two scrubs on the pad due to issues with the Atlas V and ground equipment. The first, on May 6, occurred roughly two hours before takeoff due to a “buzzing valve” that required a return to the company’s facility for replacement. A second launch attempt on June 1 was aborted due to a problem with the ground launch sequencer less than four minutes before liftoff.