NASA again postponed the return to Earth of Barry Wilmore and Sunita Williams, the the astronauts are stranded on the International Space Station completion Boeing’s Starliner capsule is damaged in the middle of this year.

The spacecraft crew arrived at the ISS in June. The purpose is to test the comprehensive capabilities of the Starliner, including the launch, docking, and return systems. The mission is scheduled to last one week. Five of the capsule’s 28 thrusters failed to engage before docking with the ISS. Boeing claims that its technology can guarantee the safe return of astronauts. However, NASA expressed doubts and concluded that the risk was too high. The agency has delegated the task of SpaceX.

Elon Musk’s company launched the Crew-9 mission in September to, among other things, bring back Williams and Wilmore. Until now, the trapped astronauts are scheduled to back in February aboard the Crew Dragon rocket. However, NASA announced that it expects the expedition to return to the Earth’s surface after the arrival of Crew-10, which will be sent in late March 2025 at the earliest.

The adjustment will allow SpaceX and NASA engineers to finish development of the new Dragon spacecraft, which will be delivered to the company’s facility in Florida early next month.

“The creation, assembly, testing, and final integration of a new spacecraft is a painstaking endeavor that requires a great deal of attention to detail,” said Steve Stich, manager of NASA’s Commercial Crew Program, in a statement. “We appreciate the hard work of the SpaceX. team in expanding the Dragon fleet in support of our missions and the flexibility of the station program and expedition crew as we work together to complete the readiness of the new capsule for flight.

NASA said the Crew-9 and Crew-10 crews must complete a “handover period,” during which the ISS residents share experiences and knowledge with the newcomers. This process ensures proper performance of onboard science experiments and maintenance of the orbital complex.

NASA and SpaceX specialists are examining several options for coordinating the next delivery of the crew. They determined that the March launch for Crew-10 was “the best option to meet NASA’s requirements and achieve the space station’s goals for 2025,” according to an agency press release .

A Long Haul

The ISS received two resupply flights in November, ensuring the crew had enough food, water, clothing, and oxygen. However, some experts have warned of potential health risks for Wilmore and Williams after spending more than nine months in space.

The scientific community has been studying the effects of spaceflight on the human body since the 1970s. In the years since the first lunar landing, it recognize the conditions such as loss of bone mass, weakened heart function, vision problems, and the development of kidney stones.

A recent study from University College London REFLECT that the structure and function of the kidneys can also suffer permanent damage, although this is more aggressive in the cases of astronauts very far from Earth, which does not happen in the ISS.

NASA points out that crews on ISS expeditions typically make long stays, with an average duration of six months. It added that some astronauts carry out missions of up to a year to contribute to research on human adaptation to space flight, with a view to future lunar and Martian exploration.

This story originally appeared on WIRED in Spanish and translated from Spanish.