The docking of Boeing’s Starliner spacecraft, carrying a crew of two, has been delayed after experiencing two helium leaks since entering orbit. Teams are working to fix the propulsion system, according to NASA.

The original docking with the International Space Station was scheduled for Thursday at 12:15 p.m. EST but the earliest docking could not occur before 1:33 p.m. ET, NASA says.

Butch Wilmore and Suni Williams, the astronauts on board, were around 198 meters (650 feet) from the outpost, officials say, adding that the thrusters of the reaction control system (RCS), which provide nuanced maneuvering ability, are currently having issues.

Ex-Navy test pilots Wilmore and Williams were manually piloting the Starliner and initiating “hot fire tests” in hopes of restarting the thrusters.

It is currently unclear if the helium leaks and the thruster issues are related.

After years of delays and two failed launches, Starliner lifted off from Florida on Wednesday. Previous setbacks included software that placed the Starliner on a bad trajectory during an uncrewed test, as well as finding flammable electrical tape in the cabin.

NASA and Boeing were aware of one helium leak in a Starliner thruster upon the first failed launch in May.

The teams decided not to repair the leak, stating that testing showed the leak rate to be within safety limits. Repairing the leak would have involved a complicated process with disassembling the Starliner in the factory.

Since beginning the mission, the Starliner has developed two more helium leaks, as posted on the NASA X account.

"Two of the affected helium valves have been closed and the spacecraft remains stable,” said the post.

Boeing spokesman Jim May also said that the leaks do not pose a safety concern for the test pilots or the overall mission, stating that the Starliner has helium reserves and that the thrusters will not be needed upon docking at the space station when the propulsion system is disabled.

The helium pressurizes the fuel lines of the thrusters for maneuvering the spacecraft, and engineers created a plan in case of additional leaks. The original leak was likely caused by a small faulty rubber seal.

Wilmore and Williams are the first crew members to fly on the Starliner.

Boeing and NASA are hoping to add a second provider with SpaceX having regular trips to the ISS already. The current trip goes toward the certification process for Boeing. This is also the sixth type of spacecraft built by the United States flying NASA astronauts.

Some information for this story came from Agence France-Presse and The Associated Press.