The return of Boeing’s Starliner capsule to Earth will be delayed a few more days due to thruster troubleshooting and a planned spacewalk.
NASA announced today (June 18) that Starliner will complete its first manned mission to the International Space Station (ISS) no later than June 26, approximately three weeks after launch. Landing that day is scheduled for 4:51 a.m. EDT (0851 GMT) at White Sands Spaceport in New Mexico. We will broadcast this live on Space.com via NASA Television.
The two-astronaut mission, known as Crew Flight Test (CFT), was originally supposed to spend about a week on the ISS, but its departure from the ISS was significantly delayed. NASA and Boeing are using the extra time to continue assessing Starliner’s thruster problems, which thwarted its first ISS docking attempt on June 6. Additionally, a postponed ISS maintenance spacewalk will now take place on June 24, two days before Starliner’s scheduled launch.
“We want to give our crews a little more time to look at the data, do some analysis, and make sure they’re actually ready to come home,” Steve Stich, NASA’s Commercial Crew Program manager, said during a livestreamed teleconference. journalists today. Starliner can be separated from docking in emergency situations, but otherwise testing continues to learn more about the vehicle’s systems.
Relating to: Thruster failures and helium leaks can’t stop Boeing’s Starliner astronaut test flight – but why are they happening?
Stich reiterated that five of Starliner’s 28 reaction control thrusters failed during the final phase of the ISS rendezvous on June 6, but four eventually came back online. (Starliner was successful in its second docking attempt, which took place a few hours later on June 6.) The evaluation of what happened is ongoing. As part of that effort, Boeing and NASA ground crew members conducted a propeller hot-fire test with astronauts over the weekend, after which Stich said everyone “felt very confident.”
Due to abnormally low pressure first observed during docking, one of the thrusters did not fire during the test and will remain offline during return to Earth. (The Canadarm2 robotic arm on the space station was also used to view the thrusters via a robotic camera, according to ISS Program Manager Dana Weigel, who participated in the teleconference.)
The docking of the CFT was a little more complicated than the only other time the Starliner approached the ISS; this was accomplished during an uncrewed test flight in May 2022. This uncrewed mission, called Orbital Flight Test 2 (OFT-2), also faced interfering thruster problems. with placement.
But “meeting [for CFT] It was a little more challenging in terms of the propulsion system. In other words, it fired its thrusters a little more frequently,” Stich said. Additionally, teams are running hardware simulations at NASA’s Marshall Space Flight Center in Alabama to model ongoing helium leaks on the Starliner.
A small helium leak in one of the Starliner’s reaction control system (RCS) thrusters was first discovered on the pad in early May after the capsule’s launch attempt was aborted due to a valve problem on the United Launch Alliance Atlas V rocket.
Many new helium leaks emerged during the mission, and fault tree analysis is ongoing to find out what happened. While Stich said the helium leaks and RCS thruster problems had different causes, Mark Nappi, vice president and program manager of Boeing’s commercial crew program, said data review continues to reveal more information about what’s going on.
The helium leak from the launch pad was not an immediate safety issue, but as NASA and Boeing investigated the issue further, they uncovered a design vulnerability in the RCS system that could affect Starliner reentry. Agency officials later approved a 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 are testing Starliner’s various systems in orbit, and ground crews continue to analyze data to better address thruster and helium leak issues.
Stich emphasized that the tests conducted in orbit on Saturday, June 15 gave the team confidence that Starliner was recovering. “Saturday was a big day to realize that the helium leaks were decreasing, the thrusters were recovering, and we could rely on the thrusters for the rest of the flight,” he said.
He said the tone of the conversation had changed, although evaluations of what happened continued. “I think we’re just doing the normal job we’re doing right now. What are the contingencies that could happen?” [with] Disconnection time frame? Once we get to that, let’s look at how we handle each of these contingencies should something happen and then look at the procedures we have in place. Are we ready to implement these?
The delayed mission return also includes a planned June 13 spacewalk, which was postponed due to “spacesuit discomfort” during preparation. NASA astronaut Matt Dominick, the ISS crew member who suffered the discomfort during today’s press conference, will not go out during the rescheduled spacewalk on June 24 to prevent it from happening again, Weigel said.
Weigel told Space.com that docking of the Starliner would be a priority if the June 24 spacewalk is postponed again, and that spacewalking NASA astronauts Tracy Caldwell Dyson and Mike Barratt will wait until after the Starliner departs to perform extravehicular activity. told.
CFT is a developmental mission. Throughout the launch and flight campaign, Boeing and NASA emphasized that mission timelines are highly variable due to Starliner flying its first mission with humans on board. Wilmore and Williams said much the same thing, based on their experience with the U.S. Navy flying complex aircraft.
“We’ve always said this is a test flight and we’ll learn some things. Here we are,” Nappi said at today’s press conference. “We learned that our helium system, although manageable, wasn’t performing. It’s still performing as designed. So we need to go figure that out.”
Nappi emphasized that the performance of most RCS thrusters was good, trending towards nominal, while helium leaks “showed to be stable and lower than measured.” [before]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, the team is working to learn more about Starliner.
“This is an opportunity to fully understand the performance of the system without schedule or time pressure,” Nappi said. He noted that aside from technical issues, the mission met 77 of the original 87 flight test targets; the remaining 10 will be evaluated during docking and landing.
Relating to: NASA evaluates potential impacts of helium leaks and more on Boeing’s Starliner astronaut test flight
Starliner, along with SpaceX’s Dragon capsule, was tasked by NASA to send agency-led crews from American soil to the ISS. (Russia also leads and launches cosmonaut-led crews on the long-serving Soyuz spacecraft.) CFT aims to certify Starliner for the first operational ISS rotation mission, called Starliner-1, expected to launch in 2025.
Dragon and Starliner were first tasked in 2014 to send NASA astronauts aloft by 2017, but funding and technical issues extended the timeline by several years. SpaceX, which based its Crew Dragon spacecraft on the company’s ISS cargo capsule, launched its first astronaut test mission in 2020 after just one uncrewed test flight. Starliner’s first crewed mission occurred four years later and required two uncrewed tests, in part because the spacecraft was a new design.
RELATED STORIES:
— Boeing’s Starliner rolls down launch pad to replace ‘buzzing’ rocket valve (photo)
— Meet the crew aboard Boeing’s 1st Starliner astronaut flight
— Boeing’s Starliner spacecraft won’t fly special missions yet, officials say
Starliner’s path to CFT was delayed after the capsule experienced problems on its first uncrewed test mission in December 2019 and failed to reach the ISS as planned. (However, astronauts often say that with developmental programs like Starliner, timelines are difficult to predict because unexpected situations can always arise.)
Boeing fixed these time-consuming glitches. The coronavirus pandemic that emerged in early 2020 further delayed the launch of the second uncrewed ISS mission, pushing it to May 2022. The CFT was next expected to launch in 2023, but that flight was postponed after problems with parachute loading and flammable tapes emerged. last year.
The CFT then underwent two scrubbing operations on the pad due to issues with Atlas V and ground equipment. The first occurred on May 6, about two hours before launch, due to a “buzzing valve” that required a return to a company facility to replace. The second launch attempt, on June 1, was canceled less than four minutes before liftoff due to a problem with the ground launch sequencer.