NASA continues to delay return of Boeing Starliner, astronauts from ISS

July 25 (UPI) -- There still is no return date set for the Starliner astronauts aboard the International Space Station, officials with NASA and Boeing said Thursday.

NASA Commercial Crew Program Manager Steve Stich in a conference call Thursday morning said the agency has made significant progress in assessing the Starliner's return capability but there is no official plan to bring the astronauts home.

"We don't have a major announcement today relative to a return date. We're making great progress, but we're just not quite ready to do that," he said.

Stich said NASA needs to first conduct a review that won't happen until the first week of August before the agency can consider a return date.

It has now been almost two months since astronauts Butch Wilmore and Sunita Williams docked to the ISS on June 5 for what was supposed to be a weeklong mission to test Boeing's long-delayed Starliner spacecraft.

The troubled mission has gone through numerous technical and software-related issues , which delayed it by about four years.

In the weeks leading up to its fateful launch, Starliner experienced issues with a vibrating oxygen valve and a small but persistent helium leak. After liftoff, the crew identified several other helium leaks, as well as failures of the reaction control system thrusters.

Boeing and NASA, meanwhile, have been troubleshooting copies of the malfunctioning RCS thrusters at a facility in White Sands, N.M. Stich on Thursday's call said the tests revealed a "bit of a bulge" in the Teflon seal, which was consistent with in-flight observations.

Boeing Vice President and Commercial Crew Program Manager Mark Nappi said in the call that the Starliner service module in White Sands had been exposed to propellant for about three years, "so it was a really good test case to go and do some leak checks on and then take that hardware apart.

"We did those leak checks. We found leaks," he said.

Nappi added the team will continue to test-fire the thrusters this weekend.

"The last several weeks have been really useful in understanding thruster and helium anomalies and how to address these problems for future flights," he said. "That's been the real goal here."

When asked about whether NASA had a contingency plan to bring the Starliner astronauts home, Stich said the agency has considered SpaceX 's Crew Dragon spacecraft, but the focus has been on returning Boeing's craft to Earth.

"Obviously the backup option is to use a different system. I would rather not go into all those details until we get to that time -- if we ever get to that time," Stitch said. "We really have our team focused on, as we close in on this final flight rationale, returning Butch and Suni on Starliner."

SpaceX, which along with Boeing is contracted under NASA's Commercial Crew Program, ran into its own issue earlier this month when its highly successful Falcon 9 rocket suffered an anomaly that resulted in the loss of a payload of 20 Starlink satellites.

The rocket had over 300 successful launches and only three failures since its debut in 2015.

The most recent failure, besides being a stain on Falcon's otherwise illustrious track record, highlighted NASA's vulnerability in having just two vendors.

"It reminds other potential customers that it's in their interest for there to be multiple providers," astrophysicist and satellite tracker Jonathan McDowell said in an interview with Space.com .

"Maybe they should give some launches to some of SpaceX's rivals, even if they're not the cheapest, just to maintain the alternative, if SpaceX has another downtime."

Boeing and NASA have repeatedly insisted that Wilmore and Williams are not "stranded" in space and that their extended stay aboard the ISS was to gather more data about the Starliner.

The astronauts, for their part, have remained optimistic. Wilmore earlier this month said in a press conference broadcasted from the ISS that they are " absolutely confident " in Starliner's capability.

"I feel confident that, if we had to, if there was a problem with the International Space Station, we would get in [the Starliner spacecraft] and we could undock, talk to our team, and figure out the best way t o come home," he said.

NASA and Boeing, however, haven't been able to ward off the bad publicity. The Atlantic writer Marina Koren in an article titled " NASA Should Ditch the Spin " said NASA bears responsibility "for its uneven supervision of Starliner's development leading up to launch and its overly guarded communications to the public since, which have done more to fan rumors about the state of the mission than dispel them."

Boeing already is under intense scrutiny for abandoning safety and quality control protocols after a fuselage blowout on an Alaskan Airlines jet in January.