NASA astronauts still aboard ISS as engineers fix helium leak on Boeing Starliner

Boeing's Starliner capsule finally launches

The Starliner capsule blasts off on its first test flight with astronauts. Here's the view provided by NASA as the mission launched from Florida.

Two NASA astronauts are still aboard the International Space Station after the Boeing Starliner that was supposed to ferry them back to Earth suffered a leak.

Barry "Butch" Wilmore and Suni Williams have been on the ISS for almost two weeks as Boeing and NASA engineers work to fix helium leaks on the Starliner.

Williams, 58, and Wilmore, 61, do not have a specified return date but will come back to Earth no earlier than June 26. This will give their teams more time to analyze data from Starliner, NASA said on Friday.

FILE - NASA astronauts Suni Williams and Butch Wilmore take their historic ride on Boeing's CST-100 Starliner as it makes its first human spaceflight on Wednesday, June 5, 2024, from Cape Canaveral Space Force Station Space Launch Complex 41. (Ricardo Ramirez Buxeda/Orlando Sentinel/Tribune News Service via Getty Images)

"We are taking our time and following our standard mission management team process," Steve Stich, manager of NASA’s Commercial Crew Program, said in a statement. "We are letting the data drive our decision making relative to managing the small helium system leaks and thruster performance we observed during rendezvous and docking."

Stich also said that given the extended duration of the mission, "it is appropriate for us to complete an agency-level review, similar to what was done ahead of the NASA’s SpaceX Demo-2 return after two months on orbit, to document the agency’s formal acceptance on proceeding as planned."

The first piloted test flight of SpaceX’s Demo-2 in 2020, however, did not experience problems like the ones seen during Starliner’s first flight with astronauts.

Starliner launched on June 5, the third attempt in just under a month to get the spacecraft safely into the atmosphere. It experienced one helium leak before blasting off and two more leaks before docking with the ISS, NASA previously said.

Despite the issues, Stich said Starliner is "performing well" in orbit while docked with the ISS.

"We are strategically using the extra time to clear a path for some critical station activities while completing readiness for Butch and Suni’s return on Starliner and gaining valuable insight into the system upgrades we will want to make for post-certification missions," Stich said.

NASA said the crew is not pressed for time to leave the ISS, noting that the space station is well-stocked with supplies in orbit.

Starliner also remains cleared for return in case of an emergency on the space station that requires the crew to leave orbit and come back to Earth, NASA said.

FOX Business contributed to this report. This story was reported from Los Angeles.