It hasn’t gone perfectly.

Instead of coming home after about eight days, the spacecraft remains docked to the station, its return delayed indefinitely while teams continue to troubleshoot a series of problems — helium leaks and a few thrusters that stopped working at a critical moment in the flight — in the capsule’s propulsion system.

While the top priority is making sure NASA astronauts Sunita Williams and Barry “Butch” Wilmore return to Earth safely, the technical delays, and whether Boeing can overcome them, reflect not only the high stakes for the future of the Starliner program, but also the company’s future in space. Boeing desperately needs to demonstrate that it can fly astronauts safely, and overcome the kinds of technical challenges that have been plaguing the spacecraft — as well as the company’s commercial aviation division.

Once the mission is complete, NASA and Boeing must undergo a rigorous process to certify Starliner for regular crew rotation missions with a full contingent of four astronauts for regular six-month stays on the station. Only then can Starliner join SpaceX’s Dragon, which first flew astronauts for NASA in 2020, and deliver on a $4.2 billion contract NASA awarded Boeing a decade ago.

NASA is eager for Boeing’s Starliner to serve as a second American transportation system to the space station. SpaceX has been serving that function alone since 2020, but NASA says it needs two systems in case one goes down.

Years of setbacks, including a botched test flight without astronauts on board in 2019, have cost Boeing some $1.5 billion in cost overruns. It needs Starliner to start flying the regular crew rotation flights so that it can start getting paid for the missions.

“I have a great deal of confidence they are looking at it very hard and they would not commit to the de-orbit of a spacecraft that was unsafe,” said Wayne Hale, the former NASA space shuttle program director who also served as a flight director for 40 shuttle flights. “For Boeing, as well as SpaceX, they make their money off the post-certification missions. Those are revenue flights. They’d like to recoup their development costs, and in fact make a profit off the exercise. So it’s important.”

Starliner has sprung a series of small helium leaks that have confounded NASA and Boeing and have led to a number of delays in getting off the ground and then coming home. Originally, the teams said they thought the leaks were due to a bad seal, but they later said they were not sure what was behind them. They are also trying to figure out why five of the spacecraft’s small thrusters suddenly stopped working as the spacecraft approached the space station on June 6, forcing NASA to have Boeing back up the vehicle and refire the thrusters to bring them back online.

Initially, Starliner was supposed to come home June 18; then NASA pushed that back to June 26. The space agency delayed it again Friday to sometime in July, saying the teams needed more time to study the propulsion system problems.

There is no rush to fly the astronauts home, NASA said. It has also said the helium leaks don’t pose a risk to the return. Four of the five thrusters are now operating normally, and since the spacecraft is outfitted with 28 such thrusters there is plenty of redundancy, officials have said. The spacecraft can stay docked in space for up to 45 days, giving crew members a little breathing room to continue to troubleshoot the issues.

NASA and Boeing have repeatedly stressed that Starliner is healthy and could be used at any time to fly the astronauts back to Earth in the case of an emergency on the space station.

“We are taking our time and following our standard mission management team process,” Steve Stich, manager of NASA’s Commercial Crew Program, said in a statement. “We are letting the data drive our decision making relative to managing the small helium system leaks and thruster performance we observed during rendezvous and docking.”

Being able to resolve the thruster problem and the helium leaks will play a prominent role in the certification review, officials have said.

“We’ve got to go address the helium leaks,” Stich said during a media briefing last week. “We’re not going to go fly another mission like this with the helium leaks.” The teams also need to find out what’s “causing the thrusters to have low thrust,” he added. “So we’ve got some of that work to do after this flight.”

The certification process, however, is not the agency’s chief concern at the moment. For now, “the whole team has been focused on understanding what’s happening with this vehicle for the crewed flight test and our plan for return. So we haven’t looked ahead too much,” Stich said. “Later this summer, we’ll lay out all the work in front of us after this vehicle comes back with the crew and then figure out what the path forward is.”

In preparation for that work, Boeing and NASA want to collect as much data as possible on the systems. Already, Boeing has test-fired the thrusters while the spacecraft has been docked to the space station. Boeing and NASA are working with simulators on the ground to test different scenarios to try to get to the root of the problems and ensure the vehicle is safe.

The certification process is a “painstaking review,” Hale said. “And clearly these two issues need to be resolved” before NASA allows Boeing to fly a full crew of astronauts. He added that “thruster failures and helium leaks are something we dealt with all the time in the shuttle program. They were very common.”

Safety is paramount, and the tragedy of the space shuttle Columbia, which came apart in 2003 as it returned from orbit, is always in the back of people’s minds, he said. “Those lessons are not forgotten,” he said.

Complicating the matter is the fact that the helium and thruster problems are located within Starliner’s service module, which provides the bulk of the spacecraft’s engine power. Before returning to Earth, it is jettisoned and burns up in the atmosphere. Engineers, then, are keen to diagnose the problems while the hardware is still accessible. That, Stich said, will allow them to gain “valuable insight into the system upgrades we will want to make for post-certification missions.”

Since “the service module doesn’t come back, they have to get all the data they can from it now,” said Mike Massimino, a former NASA astronaut and a professor of mechanical engineering at Columbia University. “You’d want to stay on orbit as long as you can to get that data.”

Williams and Wilmore are more than happy to stay in orbit as well, he said, especially since Williams was last in space in 2012 and Wilmore in 2015.

“More time in space is a great thing,” he said. “I would want to be up there. They’ve both been waiting on that flight. Why rush through it?”