When American astronauts Barry “Butch” Wilmore and Sunita Williams launched on a test mission to the International Space Station (ISS) on June 5, they expected to return home within days. However, their mission has taken an unexpected turn.

Nearly two months later, Wilmore, 61, and Williams, 58, remain aboard the ISS, with no clear timeline for their return. The pair now face the possibility of missing the entire summer—and perhaps even spending Christmas and New Year in space.

The astronauts flew to the ISS aboard a Boeing Starliner spacecraft, marking the first crewed test flight of this new spacecraft. The mission was intended to evaluate the Starliner’s performance before it becomes a regular mode of transport for astronauts. However, the spacecraft encountered several issues during its approach to the ISS, including leaks in the propulsion system and some thrusters failing.

While Wilmore and Williams safely reached the space station, their return to Earth has been put on hold until an alternative method can be arranged, should the Starliner be deemed unsafe for the journey home.

During a news briefing on Wednesday, NASA officials stated that no final decisions have been made regarding the astronauts’ return. “Our primary option is to bring Butch and Suni back on Starliner,” said Steve Stich, manager of NASA’s Commercial Crew Program. “However, we have made the necessary plans to ensure we have other options available.”