NASA will need to conduct an emergency space walk on the International Space Station next week.

Two Americans on the ISS are getting ready for a space walk to free a stalled rail car after it got stuck while flight controllers in Houston were trying to move it on the outside orbiting lab, four inches from where it locks down, according to an Associated Press report.

The car will need to be securely attached to guide rails before any visiting spacecraft can dock with the station, and since Russia plans to send supply ship up on Monday that will dock on Wednesday, the ISS needs to get the issue fixed immediately.

A stuck brake handle is the probable cause of the issue. The system transports people and equipment, including the large robot arm used on the station. Scott Kelly, NASA’s astronaut who is in the midst of a year-long stay aboard the ISS, as well as Timothy Kopra, who arrived recently, may be conducted the space walk as soon as Monday, although it may not happen until Tuesday.

Fortunately, the car ended up in the middle of the rail and not near the end, making it easier to access.

The space walk is expected to take about three hours, and the astronauts may deal with some other longer-term issues along the way.

In the meantime, NASA on Friday decided to establish regular crew missions to the ISS from Boeing Space Exploration of Houston. Boeing and SpaceX will send two crew launches to the station each year, which would set up a “sustainable future” aboard the ISS, NASA said in a statement.