WASHINGTON — Members of a NASA safety panel said they see good progress on the development of both exploration systems and commercial crew vehicles, but warn future progress could be hindered by a “bottleneck” of reviews they face.

The Aerospace Safety Advisory Panel (ASAP), meeting March 1 at NASA’s Marshall Space Flight Center, didn’t note any new major safety-related problems involving the two commercial crew vehicles under development, Boeing’s CST-100 Starliner and SpaceX’s Crew Dragon, or NASA’s Space Launch System and Orion programs.

However, members raised concerns about the fact that the simultaneous development of the vehicles could strain NASA’s ability to perform qualification and other safety reviews. That had the potential to create additional schedule pressure on those programs.

“There’s going to be a wall of verification and qualification processes which a finite number of people at NASA are going to have to wade through,” said former astronaut Sandra Magnus. She said companies, and NASA, had to be aware of how to deal with that impending wave of reviews. “This is a potential bottleneck that’s coming up.”

Neither Magnus nor other panel members offered specific solutions to the problem, beyond trying to spread out the work where possible. “Anything that the community can do now to sort of meter that work” would help, she said. “But I think that’s really the next thing we’ll have to keep an eye on as a safety panel.”

Other panel members said that they saw no evidence of schedule pressures in general creating safety issues for the vehicles under development. “The commercial crew program has shown us on the panel that, in spite of a very challenging set of circumstances they’re facing right now, they’re doing an excellent job of making decisions,” said George Nield, associate administrator for commercial space transportation at the Federal Aviation Administration.

He acknowledged, though, that the schedules published by the program, which call for both uncrewed and crewed test flights of both companies’ vehicles by the end of this year, may not be realistic. “It’s very challenging to be able to make the dates that are now being worked to,” he said. “But, encouraging to us is that we don’t see any sign of schedule pressure negatively impacting the decisions that are being made.”

Several factors are affecting the schedule for SLS and Orion, including development of the core stage of the SLS, the service module for Orion and software. Donald McErlean, a former engineering fellow at L-3 Communications, noted that NASA’s plans call for the delivery of the core stage of the first SLS to the Stennis Space Center “very late this year” for engine tests. “While that is certainly a schedule challenge,” he said, “it is within the realm of possibility.”

ASAP endorsed a proposal last year to build a second mobile launch platform for SLS, which would shorten the gap between the first and second SLS missions. That gap, of at least 33 months, is driven by the time needed to modify the existing platform to accommodate the larger version of SLS that will be used on the second and subsequent missions. However, NASA did not request funding for a second mobile launcher in the budget proposal.

“We continue to urge that NASA look for prudent and safe ways to shorten the timeframe between flight operations to mitigate the erosion of launch operations experience,” said Patricia Sanders, chair of the panel.