In the doghouse

This is the fundamental design flaw that will cause the Starliner test flight to come to a disappointing end. The thrusters are clustered in four doghouse-shaped propulsion pods around the circular perimeter of the Starliner spacecraft's service module. Thermal modeling now shows these doghouses act like a thermos, trapping heat from the thrusters as they fire over and over in pulses.

“As we look back at OFT-2 now, with this newer lens of what we learned at White Sands, certainly we could have explored OFT-2 in a little more detail, either leading to some redesign of the doghouse to get the thermal environmental lower, or operate the thrusters differently," Stich said.

"It’s easier to do that in hindsight," he said. "If we had went back and thought about the whole integrated problem a little bit more, could we have done some kind of testing? What I would say is it’s very difficult to test the doghouse environment on the ground, where you’ve got thrusters that fire in multiple directions, and it's very hard on the ground to have a test facility, a vacuum chamber, that accommodates thruster firings in multiple directions.

"We thought, obviously, we had done enough analysis to show that the thrusters would be within the temperatures that they were qualified for," Stich said. "Clearly, there were some misses in qualification. We’re going to go through that data in more detail post-flight, and then figure out what we can do to go fix them.”

He said NASA is also re-evaluating its qualification and certification processes to determine if the agency should change any of its procedures to reduce the chance of any similar misses in the future.

Scott Hubbard, a former director of NASA's Ames Research Center and a member of the Columbia Accident Investigation Board, told Ars earlier this month that NASA and Boeing should revisit their decision to launch the Crew Flight Test with unresolved technical problems. "Was the decision well-supported, or did someone have 'launch fever?'" Hubbard asked.

Starliner's problems go back much further than 2022. Software woes cut short Starliner's first test flight in 2019 before it could dock at the International Space Station, and they forced Boeing to fly a second test flight, OFT-2, to gain confidence that the spacecraft could safely fly astronauts. NASA and Boeing then delayed the second unpiloted test flight nearly a year to overcome an issue with corroded valves in the ship's propulsion system.

Last year, just a couple of months before it was supposed to launch on the crew test flight, officials discovered a design problem with Starliner's parachutes and found that Boeing installed flammable tape inside the capsule's cockpit. All of that happened before Starliner reached the launch pad for the CFT mission.

SpaceX, which NASA has tapped to rescue the Starliner crew, has now launched eight operational long-duration crew missions to the International Space Station to date, plus an initial piloted test flight of the Dragon spacecraft in 2020, and several more fully private human spaceflight missions. SpaceX has finished all of its work in its initial commercial crew contract with NASA, and is now working off of an extended contract to carry the program through 2030, the planned retirement date for the ISS.

What's next for Starliner?

NASA officials said Saturday it is premature to decide whether the agency will require Boeing to conduct yet another test flight of the Starliner spacecraft, or if Starliner could be pressed into operational service after Boeing resolves the myriad problems with the craft's propulsion system.

In either case, don't count on another Starliner crew flight next year. NASA will have to continue leaning on SpaceX, which has shown it is up to the task of launching long-duration crews to the space station every six months. The agency's goal from the start of the commercial crew program has been to fully certify SpaceX and Boeing for operational crew missions, allowing NASA to alternate between Crew Dragon and Starliner missions, with each company flying once per year.

This would give NASA another layer of redundancy for getting its crews to the space station. Right now, the prime route is through SpaceX. NASA continues to fly one astronaut on each Russian Soyuz spacecraft, in exchange for a seat for a Russian cosmonaut on each SpaceX crew mission.

It's not yet clear if NASA will officially classify the situation with the Starliner Crew Flight Test as a "mishap" or a "loss of mission." Such a determination could trigger a more formal independent investigation, which might trigger longer delays in Starliner's next flight, in whatever form it takes.

One thing that could complicate the investigation into the thruster problem is that the control jets are located on the Starliner service module, which jettisons from the crew section of the spacecraft before reentry. The service module will burn up over the Pacific Ocean, so engineers won't have a chance to get their hands on the suspect hardware.

Assuming the investigation doesn't uncover any additional problems, and NASA and Boeing return Starliner to flight with astronauts in 2026, there will not be enough time left in the space station's remaining life—as it stands today—for Starliner to fly all six of its contracted missions at a rate of one per year. It's difficult to imagine a scenario where NASA elects to fly astronauts to the space station exclusively on Starliner, given SpaceX's track record of success and the fact that NASA is already paying SpaceX for crew missions through the end of this decade.

It is noteworthy to mention here that NASA has only given Boeing the "Authority To Proceed" for three of the potential six 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.

The commercial crew contracts are structured as Indefinite Delivery/Indefinite Quantity (IDIQ) agreements, where NASA can order individual missions from SpaceX and Boeing as needed. If SpaceX keeps performing well and the space station is actually decommissioned in 2030, it may turn out that NASA officials decide they just don't need more than three operational flights of Starliner.

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.

After retiring the International Space Station, NASA wants commercial companies to deploy human outposts in low-Earth orbit. Ideally, these future space stations will be cheaper to operate than the ISS, and open to use by NASA and money-making commercial ventures. Future space station operators will require transportation for crew and cargo, just as the ISS does.

Some companies involved in commercial space stations are in direct competition with SpaceX. For example, Blue Origin, Jeff Bezos's space company, has partnered with Boeing to ferry people to and from its proposed Orbital Reef space station using Starliner, rather than choosing SpaceX for the job.

But there are many open questions about when the first commercial space stations might be in orbit, and the market outlook for these projects. In the end, with human lives at stake and a bottom line to worry about, the owners of a private space station will almost certainly go with the less expensive, flight-proven vehicle to transport people to and from orbit.

NASA and its international partners haven't ruled out extending the life of the ISS beyond 2030. If that happens, Boeing's Starliner could be in the mix for more crew flights. However, once NASA and its partners give the "go" to nudge the ISS out of orbit, its fiery plunge through the atmosphere will not just be the coda to 30-plus years of space station operations, it may also mark the end of Boeing's foray into the realm of commercial human spaceflight.