The two astronauts testing Boeing’s new Starliner spacecraft were supposed to begin their way back to Earth on Wednesday evening, but will instead remain on the International Space Station (ISS).
The ship’s return to Earth had already been delayed due to problems with some of its engines and a leak of helium gas that pushes fuel into the propulsion system.
NASA is conducting a high-level review of technical issues before deciding when to bring the astronauts home.
Sonny Williams and Butch Wilmore are not in danger, but what went wrong with the spacecraft and what does it mean for their journey home?
Starliner was launched on June 5 despite a minor helium leak. Helium is used to push propellants into propulsion systems used to maneuver in space and slow reentry into Earth’s atmosphere.
The leak was so small that engineers thought it would not affect the mission, so they continued with the launch.
But four more helium leaks occurred during the mission, and five of 28 maneuvering thrusters cut off during approach to the space station, four of which were restarted.
The mission was supposed to last eight days, but the return date was postponed as engineers investigated the issues.
Then on June 18, NASA announced that Starliner would begin its journey home at 22:00 EDT on Wednesday, June 26 (03:00 Thursday, June 27, GMT).
NASA had previously stated in a post on its blog that the leaks do not pose any risk to the safety of astronauts because: “Only seven hours of free flight time are required to perform a normal end to the mission, and the Starliner currently has enough helium in its tanks.” To support 70 hours of free flight activity after undocking.
But just a few days later, following high-level meetings, NASA concluded that the scheduled return date should be “revised” to a date in July. No additional information was provided about the reason for the decision change.
NASA stated that aerospace engineers wanted to study the spacecraft to reach the bottom of the rifts before it re-enters the Earth’s atmosphere. That’s because while the crew capsule parachutes to Earth, the Starliner’s faulty lower “service module” will burn up upon reentry, meaning some information about what went wrong will be lost.
The space agency stressed that the astronauts were not stranded and that the Starliner was certified to return to Earth in the event of an emergency on the International Space Station.
What happens next is subject to a high-level, agency-wide review by NASA to determine what to do next.
The sequence of events raises questions about whether the launch should have gone ahead despite the leak.
Dr Adam Baker, president of Rocket Engineering, a British company specialising in rocket propulsion systems, says he understands why the rocket was launched, but says it would have been better to get to the source of the leak and fix it.
“There is a danger that by trying to make things too perfect, it ends up taking too long and too expensive, and as a result, public and political support disappears,” he said.
“But what I feel is that they may not have adequately taken into account the worsening of the leak after launch. This is something that NASA and Boeing probably should have done.”
This would have been very expensive, because it would have involved removing the rocket from the launch pad and removing the propulsion system from the spacecraft.
Another issue for NASA to examine is why these issues were not identified in any of the two previous unmanned flight tests of the Starliner vehicle, according to Dr. Simon Barber, a space scientist at the Open University.
“The problems we have seen in the past few weeks are not the kind we would have expected at this stage of the Starliner development program,” he says.
“The whole point of this was to test what putting astronauts in the control loop of the spacecraft could do in terms of performance. Instead, we seem to be dealing with more fundamental issues that should have already been resolved by now.”
Finally, for NASA, a crucial issue is determining the underlying cause of the helium leak and propulsion problems. Until they do, all analyzes of risks for the safe return of astronauts and any contingency plans will be incomplete, according to Dr. Barber.
“Unless the root cause is understood, they will have to make a return judgment based on incomplete information. If you do not fully understand the cause of any failure, you cannot say with certainty that you do not have a systemic problem that will impact not only the underlying payment system, but also On backup systems.
As a last resort, NASA and Boeing could return astronauts aboard a SpaceX Dragon capsule, which would cause major embarrassment for Boeing. But according to Dr. Becker, we’re not there yet.
“With new spacecraft, you have to expect the unexpected,” he says. “This is a completely expected bump in the road and I don’t think it’s a major concern, other than it needs to be analyzed and repaired before the crew’s next flight.”
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