VOA科学技术2024--Spacecraft Problems Could Keep NASA Astronauts at Space Station until February（在线收听）

Two American astronauts could remain at the International Space Station (ISS) until February if the spacecraft that transported them cannot be fixed to safely bring them home.

The U.S. space agency NASA said last week it had not yet made return plans for astronauts Butch Wilmore and Suni Williams. The two have been aboard the ISS since June 6.

The American astronauts were expected to stay in space for only a week. But technical issues with the Boeing-built Starliner spacecraft have so far prevented a return trip.

The trip that carried Wilmore and Williams was a test flight for Starliner that marked the first time the spacecraft successfully carried astronauts to space.

NASA looking for a solution

NASA officials held a news conference Wednesday to discuss the ongoing situation with Starliner and the astronauts at the ISS. They said the agency is still working with Boeing to find a solution for the spacecraft's technical difficulties. Investigations have centered on helium leaks and thruster problems with Starliner.

But if those issues cannot be resolved in the coming weeks, NASA said it could decide to use SpaceX's Crew Dragon spacecraft to bring the astronauts back to Earth. NASA has been using SpaceX's Crew Dragon to regularly carry astronauts and supplies to the ISS since 2020.

If NASA decides to use Crew Dragon, it said it would leave two of four seats open during the spacecraft's next planned launch to the ISS in late September. Wilmore and Williams would then make the trip back to Earth with Crew Dragon.

NASA officials told reporters they had brought in additional experts to examine Starliner's leak issues and thruster failures. At the same time, the space agency is looking more closely at SpaceX as a backup solution to get the astronauts back home.

The agency's space operations mission chief, Ken Bowersox, said NASA's current thinking is that "we could take either path." He added that during a recent meeting, "We heard from a lot of folks that had concern, and the decision was not clear." NASA has said a final decision should be made by mid-August.

Boeing representatives did not take part in the news conference. But the company issued a brief statement Wednesday repeating its position that Starliner could still be fixed to safely transport the astronauts. "We still believe in Starliner's capability and its flight rationale," Boeing said.

The Boeing statement said if NASA did decide to change Starliner's mission, the company would "take the actions necessary to configure Starliner for an uncrewed return."

Steve Stich is the commercial crew program manager for NASA. He said the agency was not seriously considering launching a separate SpaceX flight to pick up Wilmore and Williams.

Problems with thruster's seals

Officials said tests run by Boeing and NASA on Earth have reproduced Starliner's thruster problems. This has suggested to engineers a possible issue with the thruster's seals. But Stich noted it was not clear what is causing the seal issues.

The thrusters are important for permitting Starliner to back away from the ISS during its separation operations. At the same time, engineers are seeking to find the cause of helium leaks in the spacecraft's propulsion system. The first leak happened before the launch, but more appeared during flight.

Boeing has faced repeated delays as it struggles to complete NASA's flight testing process before it can receive approval to start running official trips to the ISS.

Words in This Story

thruster - n. an engine that produces propulsion by releasing a jet of fluid or a stream of particles

rationale - n. a group of reasons for a particular decision or belief

configure - v. to arrange something or put its parts together in a particular form or pattern

propulsion - n. a force that pushes something forward