NASA’s plan to human-rate commercial crew vehicles in parallel with their private development using federal seed money may not produce safety levels acceptable for U.S. and U.S.-partner astronauts, members of a key House panel worried Sept. 14.

In testimony before the House Science, Space and Technology Committee, Associate Administrator William Gerstenmaier outlined plans to start certifying commercial vehicles next February under a “hybrid” process designed to insert some of the rigor of standard Federal Acquisition Regulation (FAR) procurement into the Space Act Agreements (SAAs) the agency is using to help fund commercial vehicle development.

But Joseph Dyer, chairman of the independent Aerospace Safety Advisory Panel, cautioned that the parallel development and certification is a “workaround” that may not produce the desired results, particularly as uncertain budgets generate downward pressure on safety spending.

“It’s not yet clear to us how waivers and deviations will be approved, who is accountable, and how the process shall be administered,” said Dyer, a naval aviator who retired as a vice admiral. “[And] both from the Congress’s and NASA’s perspective, budget and budget stability are a significant challenge.”

Gerstenmaier, who runs the Human Exploration and Operations Mission Directorate, said NASA is restricted to spending $406 million on commercial crew development this fiscal year in the absence of a fiscal 2013 budget figure from Congress, and will need on the order of $830 million a year beginning in fiscal 2014 to meet its plan to fly humans in a commercial vehicle by the end of 2017.

Gerstenmaier testified that, collectively, the private companies using NASA funds to develop commercial crew vehicles — Boeing, Sierra Nevada and SpaceX, in the most recent round — are investing only 10-20% of their internal funds in the effort. But under their SAAs, the space agency has no direct way to evaluate company spending as part of an estimate of what it will cost to fly astronauts on their vehicles.

Ultimately, he said, NASA probably will pick just one of the contenders to supply transportation services to the International Space Station, at a cost the agency is budgeting at the roughly $62 million a seat it pays Russia for Soyuz transportation and training. The competition in development probably will help hold that cost down, while the parallel certification will avoid costly rework later on, he said.