NASA and Boeing have delayed the return of the CST-100 Starliner spacecraft from the International Space Station until at least early July to continue investigating problems with its propulsion system. In a statement released late June 21, NASA announced that plans announced three days before Starliner was to depart the station on June 25 and land at White Sands, New Mexico, early June 26, were no longer being fulfilled. Crew Flight Test (CFT). The mission with NASA astronauts Butch Wilmore and Suni Williams on board.

Unlike the previous three delays, NASA is not announcing a new Starliner launch date. Instead, NASA said it was only “evaluating future return options” for the spacecraft following its planned July 2 spacewalk, the second of a pair of spacewalks planned for the ISS.

“We are taking our time and following standard mission management team,” Steve Stich, NASA’s commercial crew program manager, said in a statement. “We let the data guide our decisions to manage engine performance and the minor helium system leaks we observed during rendezvous and docking.”

He added that NASA plans to conduct an agency-wide review of Starliner before launch “given the length of the mission.” The Starliner was only scheduled to spend eight days at the station, but the latest delay means it will spend about a month there.

At a June 18 briefing in which NASA announced that Starliner would return on June 26, Stitch and others expressed confidence that the spacecraft would be ready by then. Testing confirmed that all but one of the reaction control system engines performed well and that helium leaks in the engine system were reduced when checked during engine testing.

“We really like the opportunity on the 26th, ^before He said this was a great opportunity to get into the White Sands spaceport,” Stitch said at the time, as the pre-dawn landing time meant winds were likely to be light.

The extra time will allow for more data collection and work around two planned spacewalks, he said in a statement. “We are using the extra time strategically to pave the way for some important activities on the station, while completing preparations for Butch and Suna’s return to Starliner and gaining valuable information about the system upgrades we will want to make for post-certification missions.”

But agency officials have previously said they planned the spacewalks to avoid conflicts with potential Starliner launch dates. Dana Weigel, NASA’s ISS program manager, said at a June 18 briefing that if the first of two spacewalks scheduled for June 24 is postponed, docking of the Starliner, scheduled for June 25, will be prioritized. “We’ll make sure we work within the Starliner schedule.”

However, in the same briefing, officials emphasized that they did not comply with the schedule. “We have an opportunity to expand a little bit, and it really is an opportunity,” Mark Nappi, Boeing’s vice president and commercial crew program manager, said at the time. He noted that the originally planned eight-day stay was the minimum period that could be extended if necessary to collect data, especially since the service module containing the propulsion system did not return to Earth at the end of the mission.

“This is an opportunity to fully understand system performance without schedule or time pressures. “We have time,” he said. “We will let the data guide our decisions.”

NASA’s statement did not say that Starliner could remain on the station for a long time, only that “due to the large amount of material in orbit, the crew did not have enough time to leave the station” and that no other mission was planned for the station. In a mid-August briefing just after Starliner docked on June 6, Stitch said the spacecraft could stay on the station for 45 days.

NASA has not given an exact date for Starliner’s next return to Earth. However, at a June 18 briefing, NASA flight manager Mike Lammers, who is supporting the CFT mission, said landing opportunities occur “every four days,” depending on the station’s orbit and the location of landing sites in the southwestern United States. This means the next landing opportunity after the spacewalk will be around July 4th.

NASA emphasized both in the June 18 briefing and in its final statement that Starliner could return Wilmore and Williams now if an emergency required an immediate return. “So far we don’t see a scenario where the Starliner won’t be able to bring Butch and Suna home,” Stitch said at the briefing. “While the service module is in orbit, we spend a little more time getting the data and learning as much as possible.”