WASHINGTON — A former senior NASA official told a House panel July 24 he has little confidence the U.S. private sector will be ready in time to meet the international space station’s logistics needs during the gap between the space shuttle’s retirement in 2010 and the fielding of its successor.

At least six U.S. firms are vying to sell space station resupply services to NASA starting around 2010. NASA is giving two of those companies – Space Exploration Technologies Corp. (SpaceX) and RocketplaneKistler – a combined $500 million in financial assistance under the Commercial Orbital Transportation Services (COTS) program to develop and demonstrate their rival resupply systems. The other four firms are getting technical advice from NASA, but no cash.

Tommy Holloway, one time NASA program manager for the space shuttle and international space station programs, told the House Science and Technology space and aeronautics subcommittee that the COTS approach can work, but that it would be foolish to bet the future viability of the international space station on a handful of small companies that say they can develop and field new spacecraft in just a few short years.

“In the long haul, I would think it would be unlikely that COTS will be able to provide a substantial part of the logistics program in the most critical period following retirement of shuttle program,” Holloway said. “I hope I am wrong, but I expect it will be several years after that before routine commercial activities are viable.”

Holloway was testifying as the chairman of a congressionally chartered independent safety task force that issued a report in February raising an alarm about NASA’s logistics conundrum and other issues confronting the international space station.

Sitting beside Holloway on the panel was his former deputy and NASA’s current human spaceflight chief, William Gerstenmaier.

defended the COTS program, but made clear NASA was not betting the future of the international space station on its success.

Instead, the agency is taking a multi-pronged approach to space station logistics that includes lining up agreements to use European, Japanese and Russian re

systems if necessary and dedicating the final two space shuttle flights to hauling up two-to-three-years’ worth of spare parts.

As for COTS, Gerstenmaier said NASA should have a good idea by the end of next year how well RocketplaneKistler’s K-1 and SpaceX’s Falcon 9-launched Dragon system are coming along. Both firms have promised to fly their rival systems by late 2008 and conduct the first station-bound demonstrations in 2009.

the international space station with food, fuel, water and fresh equipment is expected to be one of NASA’s primary challenges once the shuttle retires in 2010.

The ISS Independent Safety Task Force that Holloway chaired recommended that NASA commit now to flying the two logistics missions currently identified on the space shuttle manifest as contingency flights. Those two flights are so essential to the space station’s future viability, according to the task force, that they ought to be flown even if that means NASA has to leave the Node 3 life-support module on the ground. Node 3 and a European-supplied cupola housing a robotic arm workstation are slated to launch in 2010 on NASA’s next to last shuttle mission.

testified that NASA has budgeted for those two flights and is working this summer to add the two logistics flights to its baseline manifest, but said the agency needs more data on how long space station hardware is lasting before deciding whether to give priority to launching Node 3 or conducting a second spares flight should the shuttle’s September 2010 retirement date arrive before all 15 remaining missions have been flown.

“Next year we will be in a much better posture to see what the future looks like,” Gerstenmaier said.

Christina Chaplain, the director of acquisition and sourcing management at the U.S. Government Accountability Office, told the subcommittee that dropping Node 3 would have a substantial impact on the quality of life aboard space station since the module would bring up advanced life-support equipment, including an additional crew toilet. Likewise, leaving the cupola on the ground would deprive crews of panoramic views of the outside of the space station as well as a new workstation that would come into play when vehicles such as those being developed under the COTS program berth with the station with the aid of the robotic Canadarm.

Chaplain also said a forthcoming report from her office would raise concerns about NASA’s ability to complete all 15 remaining flights before September 2010.

“NASA will need to launch one shuttle every 2.7 months – an aggressive schedule when compared to recent launch time frames,” Chaplain said. Since the 2003 Space Shuttle Columbia disaster, NASA has averaged about one launch per 11 months. While NASA’s current manifest is achievable, she said, it does not leave much room for weather-induced delays or other setbacks.

Chaplain’s testimony prompted Reps. Tom Feeney (R-Fla.) and Nick Lampson (D-Texas) to ask Gerstenmaier what would prevent NASA from flying the shuttle beyond 2010 if necessary to complete space station assembly.

said the September 2010 cutoff is driven by budget considerations, not technical concerns. NASA has budgeted $3.6 billion for the last full year of shuttle operations. For fiscal 2011, which begins Oct. 1, 2010, NASA has budgeted just $116 million for shuttle.

Extending space shuttle operations would further delay the fielding of the Orion Crew Exploration Vehicle and its Ares 1 launcher because NASA is counting on the savings from retiring the shuttle fleet to fund the final few years of Orion and Ares development, Gerstenmaier said.

When Lampson suggested that the White House and Congress could eliminate the either/or nature of NASA’s dilemma by providing more money, Gerstenmaier replied that it would be harder and harder to add a flight to the end of the schedule as the shuttle gets closer to retirement.

“We are in the process of terminating a lot of contracts and subcontracts at this point,” he said. “We could probably reasonably … put together an additional flight. Later this year and next year we will lose that capability as we turn off suppliers.”

said NASA’s manifest accounts for bad weather. NASA’s current shuttle manifest, he said, was laid out to get all 15 remaining flights done by July 2010, about two months ahead of the September 2010 cutoff.

Holloway said that while the shuttle team has the necessary flexibility to deal with short-term schedule upsets over the next three years, he told lawmakers “it would be most difficult to recover from a longer-term delay” such as the February hail storm that badly damaged the space shuttle’s external tank, forcing NASA to postpone its first launch of the year from mid

March to early June.

NASA’s next shuttle launch is slated for Aug. 7. Two more are on the books for 2007, although Gerstenmaier said that the December flight could slip into January.