Two astronauts testing Boeing’s new Starliner spacecraft were scheduled to return to Earth on Wednesday night, but will instead remain on the International Space Station (ISS).
The craft’s return to Earth has already been delayed due to problems with some of its thrusters and a leak of helium pushing fuel into the propulsion system.
NASA is conducting a high-level review of technical issues before deciding when to bring its astronauts home.
Suni Williams and Butch Wilmore are in no danger, but what went wrong on the spaceship and what does that mean for their journey home?
The Starliner was launched on June 5, despite a small helium gas leak. Helium is used to push propellants into thruster systems used for space maneuvering and deceleration to re-enter Earth’s atmosphere.
The leak was extremely small and the engineers believed it would not affect the mission, so they proceeded with the launch.
However, there were four more helium leaks during the mission, and five of its 28 maneuvering thrusters broke 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 pushed back as engineers investigated the problems.
Then on June 18, NASA announced that the Starliner would begin its journey home at 10:00 p.m. EST on Wednesday, June 26 (03:00 Thursday, June 27 BST).
NASA previously said in a blog post that the leaks do not pose a safety risk to the astronauts because: “Only seven hours of free flight are required to perform a normal end-of-mission mission, and Starliner currently has enough helium in its tanks. to support 70 hours of free flight after disconnection.’
But just days later, after high-level meetings, NASA concluded that the planned return should be “adjusted” to a date in July. No further information was provided as to why the decision was changed.
NASA said that engineers on board wanted to study the spacecraft to get to the bottom of the malfunctions before re-entering Earth’s atmosphere. That’s because while the crew cabin parachutes to earth, the Starliner’s faulty lower “service module” burns up on re-entry, meaning the loss of some information about what went wrong.
The space agency emphasized that the astronauts were not stranded and that the Starliner was certified to return to Earth in the event of an ISS emergency.
What happens next is subject to a high level of “agency-level review” by NASA to decide what to do next.
The sequence of events raises questions about whether the launch should have continued despite the leak.
Dr Adam Baker, who heads Rocket Engineering, a UK company specializing in rocket propulsion systems, says he understands why the launch happened, but said it would be better to find the cause of the leak and fix it. .
“There is a risk that we will try to make things too perfect and that it will end up taking too long and too expensive, and as a result, public and political support will disappear,” he said.
“But I feel like they may not have considered the aggravation of the leak after launch enough. That’s something NASA and Boeing probably should have done.”
This would be extremely expensive as it would mean removing the rocket from the launch pad and removing the propulsion system from the spacecraft.
Another issue for NASA’s review is why these problems were not identified in either of the two previous unmanned Starliner flight tests, according to Dr Simeon Barber, who is a space scientist at the Open University.
“The problems we’ve seen in the last few weeks are not what we would expect at this stage of the Starliner development program,” he says.
“The whole point of it was to test what putting astronauts in the spacecraft’s control loop would do in terms of performance. Instead, we seem to be dealing with more fundamental issues that should really be resolved by now.”
Finally, there is the critical issue for NASA of identifying the root cause of helium leaks and nozzle problems. Until they do, any risk analysis of the astronauts’ safe return and any contingency plans will be incomplete, Dr. Barber said.
“Unless the root cause is understood, recovery decisions must be made based on incomplete information. If you don’t fully understand the cause of any failure, you can’t say with certainty that you don’t have a systemic problem that affects not only the primary propulsion system, but the backup sources as well.
As a last resort, NASA and Boeing may return their astronauts to SpaceX’s Dragon capsule, which would be very embarrassing for Boeing. But according to Dr. Baker, we’re not in that territory yet.
“With a new spacecraft, you should expect the unexpected,” he says. “This is a completely expected bump in the road and I don’t think it’s a major problem, other than it needs to be analyzed and fixed before the next crewed flight.”