Prime contractors on NASA’s next-generation human space exploration vehicles are finding it unusually difficult to obtain the space-qualified electronics and other components they need to stay on schedule, a situation they say will likely get worse if there is instability in the space agency’s out-year funding for the projects.

Testifying before the House Science space and aeronautics subcommittee, Lockheed Martin Vice President and Orion Program Manager Cleon Lacefield said today that the lead times for radiation-hardened electronic parts and other specialized hardware is a major challenge for meeting schedule.

“I think our supply chain in the United States is very fragile,” Lacefield said. “When we look at the triple-e parts needed for avionics, all the electronic components, in the environment that we see, which is a radiation environment in deep space, those components are very hard to find in the United States right now.”

Lacefield’s remarks were echoed by Jim Chilton, exploration vice president at Boeing , who is responsible for Space Launch System (SLS) stage development. Chilton told Aviation Week his company, too, is finding it difficult to purchase needed parts in the small lots needed for civil space development when the dwindling list of suppliers of all types of space-qualified hardware is hard-pressed to keep up with demand from customers that order in larger quantities.

Both programs have flight test schedules to meet, beginning with Lockheed Martin . NASA plans to fly an Orion testbed on a Delta IV launch vehicle in 2014 to evaluate how well its thermal protection system performs in a planetary return simulated by a two-orbit, high-apogee trajectory. Lacefield said the supply chain problem extends beyond electronic components able to withstand the environment outside the Van Allen Belts, and include the weight-saving composite parts that make up about 40% of the Orion capsule ’s structure.

“We have outsourced those composites across the country so that we would be able to meet the schedules of the 2014 flight,” he said, adding that the supply chain issue threatens pre-flight checkouts as early as next year. “We have outsourced across all of the electrical components to get the parts that we need by the time that we need to do the vehicle checkout on the pad next March, the electrical checkout, and we are waiting on those parts to enable us to do the vehicle checkout on the pad in Florida,” Lacefield said.

Boeing is working toward a 2017 first flight of the initial SLS version, with a new core stage, space shuttle/Ares I-heritage five-segment solid-fuel strap-on boosters, and a modified Delta IV upper stage . Like Lacefield, Chilton said the supply-chain issue will be a challenge in meeting that flight schedule .

Both men, and Dan Dumbacher, NASA ’s deputy associate administrator for exploration systems development , argued for steady funding from Congress to give space-component suppliers the business stability they need to keep the problem from getting worse.

“We are seeing lead times that we have never seen before,” Lacefield said.