NASA could return Starliner astronauts on Boeing or SpaceX

NASA leadership has been in deep discussion this week over whether the agency's astronauts should return on board. BoeingThe Starliner capsule failed or the alternative was to use a SpaceX ship to rescue the crew.

The agency's concern with Starliner, which carried NASA astronauts Butch Wilmore and Suni Williams to the International Space Station in early June, stems from its failure to identify a root cause for why several of the spacecraft's thrusters failed during docking, a person familiar with the situation told CNBC.

This week, NASA has been discussing the possibility of returning to the empty Starliner and instead using SpaceX’s Crew Dragon spacecraft to return its astronauts. There is no consensus among those responsible for making the decision, said that person, who called the outcome of NASA’s ongoing discussions unpredictable given the variety of factors involved.

The Starliner “Calypso” capsule has been in space for 59 days and counting. The mission is intended to be the final step in proving that Boeing's long-delayed spacecraft is safe for extended crewed missions to and from the International Space Station.

Boeing's crewed flight was initially planned for a minimum of nine days, but has been extended several times as the company and NASA conduct tests both on the ground and in space in an attempt to understand the thruster problem.

While NASA and Boeing leaders have publicly characterized the extensions as a data-gathering exercise, concerns raised in recent days reveal there is less internal confidence about whether Starliner is safe to return astronauts than the agency has disclosed.

Ars Technica was the first to report NASA's mixed view of the Starliner situation. NASA had previously noted that SpaceX serves as a backup, but has attempted to downplay that possibility, calling Boeing's Starliner the “primary option” for a return.

For its part, Boeing says it has the “flight rationale” to return Starliner with astronauts on board, meaning the company believes the spacecraft can return without too much risk.

“We remain confident in the Starliner spacecraft and its ability to safely return with the crew. We support NASA's requests for additional data, analysis and data reviews to confirm the spacecraft's safe undocking and landing capabilities,” a Boeing spokesperson said in a statement to CNBC on Friday.

If Starliner returns empty, the most likely alternative would be to bring back astronauts using SpaceX’s Crew Dragon, removing two astronauts from the Crew-9 mission, which is currently planned to send four people in the coming weeks. That would free up two seats for Wilmore and Williams.

NASA did not respond to CNBC's request for comment on ongoing discussions about Starliner, but told Ars Technica in a statement that the agency is “evaluating all options for return.”

“No decision has been made and the agency will continue to provide updates on its planning,” NASA said.

Following tests conducted over the weekend, NASA has observed that 27 of Starliner's 28 thrusters appear to be functioning properly. The thrusters, also known as reaction control system or RCS engines, help the spacecraft move in orbit.

But from an engineering perspective, not having a root cause for why five of the boosters failed on the flight to the ISS means there remains a risk that more boosters could fail during the return flight.

Mark Nappi, vice president of Boeing's Starliner program, said during a July 25 press conference that booster testing has resulted in “very significant” findings that “are likely the root cause.” But despite that, the company has yet to identify the root cause.

“We'll continue to tear down that hardware so we can eventually test this,” Nappi said at the time.

NASA must now decide whether it is willing to trust that the unknown problem with Starliner's thrusters will not arise again, or even potentially lead to other problems.

The lack of consensus at NASA emerged when the Commercial Crew Program Control Board met earlier this week to discuss Starliner’s return. PCBs are a standard part of NASA’s decision-making process, dating back to the space shuttle era, and are an effort to make sure any risks can be escalated to the highest levels of authority at the agency.

The PCB, chaired by commercial crew program director Steve Stich, has not reached a decision on whether to move forward with a flight readiness review, the agency’s next major step in setting a date for Starliner’s return. The next PCB meeting is expected to take place in the coming days, and NASA noted in a blog post Thursday that return planning will continue into next week.

If any PCB member disagrees with the decision to return Starliner with crew, the decision will be moved up the chain of command until the dissent is addressed. At present, discussions within the PCB do not have a predictable outcome as NASA staff consider the level of risk involved in returning Starliner with crew.

NASA often emphasizes that “astronaut safety remains the agency's highest priority” when making decisions about human spaceflight, an inherently risky endeavor.

But the choice facing NASA has other ramifications, threatening Boeing’s participation in the agency’s Commercial Crew Program. Boeing’s losses on Starliner already total more than $1.5 billion because of repeated setbacks and years of delays in the spacecraft’s development.

If NASA backs Boeing and returns Wilmore and Williams aboard Starliner, the agency is accepting an amount of risk that cannot currently be quantified. A major failure during the return, with the astronauts' lives at stake, would put NASA leadership under pressure to end Boeing's contract and its involvement in the program.

If NASA decides to send Starliner back empty, it will be a vote of no confidence in Boeing that could lead the company to cut its losses and withdraw from the program.

Moreover, if NASA adopts the SpaceX alternative and Starliner returns home without incident, the agency could face criticism for being seen as overreacting to a situation it publicly stated for weeks was not a significant risk.