NASA is in the final stages of vetting a review on the feasibility of accelerating the crew transport portion of its Commercial Orbital Transportation Services (COTS) program, according to Associate Administrator for Exploration Systems Rick Gilbrech.

NASA is funding SpaceX and Orbital Sciences Corp. to develop cargo capability for the International Space Station (ISS) under COTS, but so far has held off on greenlighting the crew transfer portion of the program, known as "COTS D." Only SpaceX has been actively working on a COTS D concept, with Orbital focused exclusively on cargo at this point.

SpaceX CEO Elon Musk has said he's confident his company's Dragon vehicle could be ready to transfer crew by 2011, provided NASA gives the go-ahead soon (Aerospace DAILY, May 15). Some lawmakers are pushing for the acceleration of COTS D to reduce the expected gap in U.S. human spaceflight capability between the space shuttle's 2010 retirement and the debut of the Orion in 2015.

Gilbrech, speaking June 4 in Washington, wouldn't comment yet on the feasibility study's results, or on Musk's optimism. But he cautioned that "we have to be realistic about when capability D can be executed." He further warned that if NASA is tasked to move COTS D up but not given money to do so, funds would likely have to be reprogrammed from exploration or commercial ISS cargo resupply, and "neither of those are good outcomes in my mind." If exploration took the hit, the spaceflight gap could be extended even further, and if ISS resupply becomes a billpayer, it could put further pressure on station logistics, he said.

SpaceX's first cargo-only COTS A demonstration is set for March 2010. Both SpaceX and Orbital are making good progress to reach COTS C, Gilbrech said, which involves sending pressurized cargo up to the ISS and demonstrating re-entry. But to make the leap to COTS D, "then you've got to worry about all the life support systems, rendezvous and docking, launch abort systems have to be developed and proved out," he said.

Some observers have questioned NASA's willingness to actually accelerate COTS D, speculating that the agency might consider such a move to undercut the Orion development. But if NASA does decide to move COTS D up and money is provided, Gilbrech said NASA would prefer to hold a "full and open competition" for the program.