In an update released late Friday evening, NASA said it was “adjusting” the date of the Starliner spacecraft’s return to Earth from June 26 to an unspecified time in July.

The announcement followed two days of long meetings to review the readiness of the spacecraft, developed by Boeing, to fly NASA astronauts Butch Wilmore and Suni Williams to Earth.

“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."

The NASA update did not provide any information about deliberations during these meetings, but it is clear that the agency’s leaders were not able to get comfortable with all contingencies that Wilmore and Williams might encounter during a return flight to Earth, including safely undocking from the space station, maneuvering away, performing a de-orbit burn, separating the crew capsule from the service module, and then flying through the planet’s atmosphere before landing under parachutes in a New Mexico desert.

“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.

They can gather more data about the performance of the vehicle on long-duration missions—eventually Starliner will fly operational missions that will enable astronauts to stay on orbit for six months at a time.

Saved 62% of original text.