Boeing's Starliner spacecraft, stricken with thruster problems and helium leaks, has left the International Space Station, wrapping up a disappointing test flight that has clouded the long-term future of the Starliner program.
Astronauts Butch Wilmore and Suni Williams, who launched aboard Starliner on June 5, closed the spacecraft's hatch Thursday in preparation for departure Friday. But it wasn't what they envisioned when they left Earth on Starliner three months ago. Instead of closing the hatch from a position in Starliner's cockpit, they latched the front door to the spacecraft from the space station's side of the docking port.
The Starliner spacecraft undocked from the International Space Station at 6:04 pm EDT (22:04 UTC) Friday. If all goes according to plan, Starliner will ignite its braking rockets at 11:17 pm EDT (03:17 UTC) for a minute-long burn to target a parachute-assisted, airbag-cushioned landing at White Sands Space Harbor, New Mexico, at 12:03 am EDT (04:03 UTC) Saturday.
The Starliner mission set to conclude this weekend was the spacecraft's first test flight with astronauts, running seven years behind Boeing's original schedule. But due to technical problems with the spacecraft, it won't come home with the two astronauts who flew it into orbit back in June, leaving some of the test flight's objectives incomplete.
This outcome is, without question, a setback for NASA and Boeing, which must resolve two major problems in Starliner's propulsion system—supplied by Aerojet Rocketdyne—before the capsule can fly with people again. NASA officials haven't said whether they will require Boeing to launch another Starliner test flight before certifying the spacecraft for the first of up to six operational crew missions on Boeing's contract.
A Noncommittal From NASA
For more than a decade, the space agency has worked with Boeing and SpaceX to develop two independent vehicles to ferry astronauts to and from the International Space Station (ISS). SpaceX launched its first Dragon spacecraft with astronauts in May 2020, and six months later, NASA cleared SpaceX to begin flying regular six-month space station crew rotation missions.
Officially, NASA has penciled in Starliner's first operational mission for August 2025. But the agency set that schedule before realizing Boeing and Aerojet Rocketdyne would need to redesign seals and perhaps other elements in Starliner's propulsion system.
No one knows how long that will take, and NASA hasn't decided if it will require Boeing to launch another test flight before formally certifying Starliner for operational missions. If Starliner performs flawlessly after undocking and successfully lands this weekend, perhaps NASA engineers can convince themselves Starliner is good to go for crew rotation flights once Boeing resolves the thruster problems and helium leaks.
In any event, the schedule for launching an operational Starliner crew flight in less than a year seems improbable. Aside from the decision on another test flight, the agency also must decide whether it will order any more operational Starliner missions from Boeing. These "post-certification missions" will transport crews of four astronauts between Earth and the ISS, orbiting roughly 260 miles (420 kilometers) above the planet.
NASA has given Boeing the "Authority To Proceed" for only three of its six potential operational Starliner missions. This milestone, known as ATP, is a decision point in contracting lingo where the customer—in this case, NASA—places a firm order for a deliverable. NASA has previously said it awards these task orders about two to three years prior to a mission's launch.
Josh Finch, a NASA spokesperson, told Ars that the agency hasn't made any decisions on whether to commit to any more operational Starliner missions from Boeing beyond the three already on the books.
"NASA’s goal remains to certify the Starliner system for crew transportation to the International Space Station," Finch said in a written response to questions from Ars. "NASA looks forward to its continued work with Boeing to complete certification efforts after Starliner’s uncrewed return. Decisions and timing on issuing future authorizations are on the work ahead."
This means NASA's near-term focus is on certifying Starliner so that Boeing can start executing its commercial crew contract. The space agency hasn't determined when or if it will authorize Boeing to prepare for any Starliner missions beyond the three already on the books.
When it awarded commercial crew contracts to SpaceX and Boeing in 2014, NASA pledged to buy at least two operational crew flights from each company. The initial contracts from a decade ago had options for as many as six crew rotation flights to the ISS after certification.
Since then, NASA has extended SpaceX's commercial crew contract to cover as many as 14 Dragon missions with astronauts, and SpaceX has already launched eight of them. The main reason for this contract extension was to cover NASA's needs for crew transportation after delays with Boeing's Starliner, which was originally supposed to alternate with SpaceX's Dragon for human flights every six months.
The commercial crew contracts are structured as fixed-price Indefinite Delivery/Indefinite Quantity (IDIQ) agreements, where NASA can order individual missions from SpaceX and Boeing as needed. NASA and its international partners plan to decommission and retire the ISS in 2030. SpaceX and NASA are working to extend the service life of each reusable Crew Dragon spacecraft from five to 15 missions, and SpaceX will bring online a new, fifth Crew Dragon for its fleet next year.
With plenty of service life remaining in SpaceX's Dragon fleet, NASA could decide that more Dragon missions, along with the handful of Starliner flights already on order, are enough to keep the ISS fully staffed through 2030. But that would mean NASA turning its back on a decade-and-a-half of established policy. Apart from ensuring redundancy for crew transportation to the space station, one of the reasons for selecting two contractors in 2014 was to allow Boeing and SpaceX to compete on technical ability and price. A decade later, there's a clear winner on these criteria.
Boeing has not issued a public statement on its long-term commitment to the Starliner program since NASA's decision to end Starliner's Crew Flight Test (CFT) mission, but we do have second-hand information from Boeing's CEO, Kelly Ortberg, relayed through NASA Administrator Bill Nelson. "He expressed to me an intention that they will continue to work the problem once Starliner is back safely, and that we will have our redundancy and our crewed access to the space station," Nelson told reporters on August 24.
The fixed-price structure of NASA's commercial crew contracts places Boeing on the hook for cost overruns on the Starliner program, which has been significant. As of July, Boeing has reported nearly $1.6 billion in financial charges to pay for delays and unanticipated technical problems on Starliner. More financial losses for the Starliner program are likely in the year ahead to cover fixes for the thruster problems and helium leaks that plagued the ongoing test flight.
Until now, NASA has paid Boeing roughly $2.7 billion of the $4.6 billion total potential value of its commercial crew contract, according to Finch. The Starliner contract NASA awarded Boeing in 2014 originally had a maximum value of $4.2 billion, but contract modifications since 2014 have added $400 million to the deal. Most of the money NASA has paid Boeing to date has been for Starliner development costs, while the remaining funds under the contract cover future service payments for operational flights.
So, if Boeing walked away from Starliner, the company would be giving up nearly $1.9 billion on potential revenue from NASA, still more than the $1.6 billion in losses it has taken on the program so far.
Ready for Departure
Since deciding last month to fly Starliner home without its crew, NASA managers have reviewed plans for the spacecraft to depart the space station in autopilot mode. The preparations included updating Starliner's software parameters to enable the autonomous undocking. Then, last Thursday, NASA officials convened a Flight Readiness Review and cleared Starliner to return to Earth.
"Everybody polled 'go' in that review, pending the operational status of the vehicle and the landing weather," said Steve Stich, NASA's commercial crew program manager. "So we're proceeding toward undock and landing on Friday."
As Starliner approached the space station on June 6, five of the ship's 28 Reaction Control System (RCS) thrusters dropped offline, requiring Wilmore to take manual control while ground controllers tried to recover some of the control jets.
Engineers tested thrusters and analyzed data for over two months to track down the cause of the thrusters' failure. Ground teams were able to bring four of the five failed thrusters back online, but NASA officials could not assure themselves the same thrusters, or perhaps more, won't overheat again and fail as Starliner departs the station and heads for reentry.
Investigators found that repeated pulses of the RCS jets led to rising temperatures in the thrusters. This likely caused a seal in each of the problematic thrusters to bulge and deform, restricting the flow of propellant, according to NASA officials.
Stich said Wednesday that possible solutions to the problem on future Starliner flights range from changing the way the ship fires its thrusters to prevent overheating, to changing the seal design, to modifying the doghouse-shaped propulsion pods where the thrusters reside on the spacecraft's service module. The design of these "doghouses" cause them to retain heat like a thermos, exacerbating the thermal problem.
Boeing and NASA also must resolve helium leaks that plagued the Starliner test flight. Engineers believe a separate set of degraded seals is causing helium leaks, which the spacecraft uses to pressurize the propulsion system and drive propellants into its thrusters. Ground controllers have closed valves to isolate the helium system and close off the leaks while Starliner has been docked at the space station. Those isolation valves will open before Starliner departs the space station, but NASA officials say the spacecraft has more than enough helium for the six-hour flight from undocking until landing Friday night.
Wilmore and Williams originally planned to stay at the space station for around eight days, but will now remain as residents on the complex until February, when they will come home in a SpaceX Dragon spacecraft.
Dana Weigel, NASA's ISS program manager, said Wednesday that the Starliner astronauts, both veterans of previous six-month stays on the space station, are fully trained to perform spacewalks, operate the lab's robotic arm, and conduct maintenance and scientific experiments. They will be fully integrated into the space station's long-duration crew, which usually includes seven residents. With the Starliner crew's extended stay, the station crew size has grown to nine people.
The crew shakeup forced NASA to remove two astronauts from the next SpaceX Dragon crew flight launching to the ISS later this month, leaving two seats empty to accommodate Wilmore and Williams when the Dragon spacecraft returns to Earth early next year. This upcoming SpaceX crew rotation will bring the station crew size back to its usual complement of seven US astronauts and Russian cosmonauts.
This story originally appeared on Ars Technica.
