The story so far: Veteran American astronauts Sunita Williams and Barry ‘Butch’ Wilmore have been docked at the International Space Station (ISS) since June 6. They have faced delays, space debris threats, helium leaks and technical issues with Boeing’s Starliner spacecraft they travelled on. The two NASA astronauts who travelled to the ISS last month said on Wednesday (July 10), that they were confident the capsule would safely bring them back to Earth.
However, their return has been delayed indefinitely as NASA and Boeing work to figure out the cause of multiple failures of thruster—a small rocket engine used to control the movement, or direction, of spacecraft by providing short bursts of propulsion—and the problem of helium leaks.
During a brief press conference from the space station, Barry Wilmore, 61, who has flown twice before, said they were “completely confident” about the return journey. Despite the problems that beset their journey to the space station, The Washington Post quoted Wilmore as saying that the ‘Starliner’ spacecraft’s performance was “really impressive”.
When he manually took control of the autonomous spacecraft as it neared the ISS on June 6, he noticed that the thrust was not as strong. He later stated that, at that moment, the reason for this fault was not known since it had just occurred. You could tell the thrust was weaker, but it was still quite impressive.”
Indian-origin Sunita Williams, 58, also on her third spaceflight, said she was confident that the spacecraft would bring them back home safely. However, it is still uncertain when that will happen. NASA and Boeing are now working to figure out why five of the spacecraft’s ‘reaction control thrusters’ got non-functional while it approached the space station.
Four of the five thrusters eventually started working again, which allowed Starliner to dock successfully. NASA has decided not to depend on the fifth thruster on the journey back to Earth. The spacecraft has 28 thrusters in total on its service module.
On top of those issues, Starliner has developed five small helium leaks in its propulsion system. NASA has stated that the leaks are minor and that the spacecraft has enough helium, which is used to pressurize the propulsion system, ensuring a steady and reliable flow of fuel to the engines for efficient operation to complete the mission.
In a separate briefing on Wednesday (July 10), Steve Stich, head of NASA’s commercial crew programme, stated that, if the tests showed no major problems with the thrusters, the crew could return by end-July. He added that they would review the data step by step and decide the best time to undock from the space station.
This is Starliner’s first mission with humans on board, serving as a test to evaluate the vehicle’s performance before NASA approves it for carrying four astronauts to the space station for up to six months. SpaceX, the other company NASA uses for crew transport, has been flying astronauts to the space station in its Dragon capsule since 2020.
Williams and Wilmore were originally scheduled to stay on the space station for about 10 days. The undocking and return of Starliner, initially set for June 18, were postponed to June 22, then June 25 and later to July 2. Ultimately, NASA delayed the return indefinitely to better understand the spacecraft’s issues. The White Sands Missile Range in New Mexico is the new testing theatre, where the Starliner’s flights to and from the ISS are being replicated to figure out the reason for the glitches.
According to Stich, they were actually taking the time to thoroughly check everything and make sure there were no surprises left. In a briefing late last month, he clarified that the members of the crew were not stuck in space and that no rescue operation was planned. Stich said Wilmore and Williams were not stranded in space and they would be brought back on the Starliner when the time proved right.
On Wednesday (July 10), he reiterated that the main plan was to return Wilmore and Williams on the Starliner and there was no reason to change that as of now. He also mentioned SpaceX’s Dragon spacecraft, noting that they had two vehicles and two different systems to bring the crew back. That gave them more time to review the data and decide if any changes were required.
The SpaceX spacecraft, which transported four astronauts to the ISS in March, can take more people in an emergency. However, this would be the last resort if the Starliner were not functional. He also mentioned that there had been no talk of sending another Dragon to rescue Wilmore and Williams.
NASA has consistently stated that the Starliner was approved to fly the astronauts home in an emergency. Late last month, Wilmore and Williams had to board Starliner when a satellite broke apart in orbit, possibly endangering the space station. The debris floated by without causing any damage. NASA flight director Ed Van Cise said the Starliner was working very well. While on the station, Williams and Wilmore have continued testing the spacecraft, in the process putting four astronauts aboard it to check out the life-support systems.
Williams said that being on the space station felt like returning home. It felt good to float around and work there with the ISS team. She also said that it was great to be up there and was not complaining about staying a few extra weeks.
(Girish Linganna is a Defence and Aerospace Analyst based out of Bengaluru. He is also Director of ADD Engineering Components, India, Pvt. Ltd, a subsidiary of ADD Engineering GmbH, Germany. The views expressed in this article are of the author only.)
