Why Indian-origin astronaut Sunita Williams’ return from space has been delayed
Problems with the capsule's propulsion system, used to manoeuvre the spacecraft, prompted NASA and Boeing to delay the flight home several times while they analysed the trouble
Uncertainty looms large over the return of the Starliner spacecraft, which took NASA astronauts Sunita Williams and Butch Wilmore to the International Space Station (ISS) earlier this month.
Following lift-off on June 5, the Boeing-built spacecraft docked at the ISS and was scheduled to begin its return journey towards Earth on June 26. However, it has now been postponed.
These astronauts will stay longer at the International Space Station as engineers troubleshoot problems on Boeing's new space capsule that cropped up on the trip there.
No return date finalised
NASA on Friday did not set a return date until testing on the ground was complete and said the astronauts were safe.
“We're not in any rush to come home,” said NASA's commercial crew programme manager Steve Stich.
Veteran NASA test pilots Butch Wilmore and Sunita Williams blasted off aboard Boeing's Starliner capsule for the orbiting laboratory on June 5. It was the first astronaut launch for Boeing after years of delays and setbacks.
The test flight was expected to last a week or so, enough time for Wilmore and Williams to check out the capsule while docked at the station. But problems with the capsule's propulsion system, used to manoeuvre the spacecraft, prompted NASA and Boeing to delay the flight home several times while they analysed the trouble.
Spacewalk postponed
They also wanted to avoid conflicting with spacewalks by station astronauts. But a spacewalk this week was cancelled after water leaked from an astronaut's spacesuit. The issue hasn't been resolved and the planned spacewalk next week was postponed.
As Starliner closed in on the space station a day after launch, last-minute thruster failures almost derailed the docking. Five of the capsule's 28 thrusters went down during docking; all but one thruster was restarted.
Starliner already had one small helium leak when it rocketed into orbit and several more leaks sprung up during the flight. Helium is used to pressurise fuel for the thrusters. Boeing said this week that the two problems aren't a concern for the return trip.
In delaying the astronauts' return, NASA and Boeing said they needed more time to collect information about the thruster trouble and leaks while the capsule was docked. Both are in the service module, a unit attached to the capsule that burns up during re-entry.
May stay at ISS for 45 days
NASA initially said the Starliner could stay docked at the space station for up to 45 days due to battery limits. But in-flight tests have shown that limit can be extended, Stich said.
Officials said they won't set a return date while they do ground tests of capsule thrusters in the New Mexico desert. They want to try to replicate the situation that occurred during docking.
“I want to make it very clear that Butch and Suni are not stranded in space," said Stich, adding that Starliner is designed for a mission of up to 210 days.
After the space shuttle fleet retired, NASA turned over astronaut rides to private companies. Elon Musk's SpaceX has made nine taxi flights for NASA since 2020. NASA plans to alternate between SpaceX and Boeing in ferrying crews to and from the space station.
(With agency inputs)
