The best thing Congress can do to ensure there is no gap between the retirement-bound space shuttle and its replacement vehicle is to give NASA enough money to accelerate development of the Crew Exploration Vehicle (CEV). For its part, NASA must make sure that it pursues a CEV design that takes advantage of existing technology — a safe, reliable design that will get the job done, not one that entails another push for revolutionary technology that may or may not be attainable in the near future.

Sens. Kay Bailey Hutchison (R-Texas) and Bill Nelson (D-Fla.), the chairman and ranking member, respectively, on the Senate Commerce, Science and Transportation science and space subcommittee, introduced language in a 2006 NASA authorization bill that would require the agency to keep flying the shuttle until a replacement vehicle has flown already. The full Commerce Committee approved the bill June 23.

On its face, the language sounds like a common sense idea. Even NASA Administrator Mike Griffin has said the United States must have its own means of getting astronauts to and from space.

But the language is in fact a bad idea because it would serve as a beachhead for those who would like to keep flying the three remaining space shuttles indefintely.

The shuttle is an amazing machine capable of launching large payloads into orbit and bringing a lot of experiments or even whole satellites back to Earth. But two accidents and 14 deaths in 17 years have proved it to be too unreliable to count on for much longer. Mr. Griffin rightly has insisted on retiring the shuttle fleet no later than 2010. A CEV that is properly designed and managed as well as adequately funded should deliver a good, reliable and safe replacement vehicle around that time.

The language in the Senate’s version of the NASA authorization bill would put the CEV schedule at risk because of the very real possibility that funding for the development effort would be siphoned-off to feed the shuttle program’s insatiable appetite.

The bill also would require NASA to develop a plan for the transition to the CEV and a new heavy-lift vehicle that “uses the personnel, capabilities, assets and infrastructure of the space shuttle to the fullest extent possible.”

While that seems to be the direction NASA is headed at the moment — Mr. Griffin has spoken publicly of his preference for a shuttle-derived vehicle for the nation’s heavy-lift launch needs — that is the kind of decision best left to engineers, not lawmakers.

The Senate bill does have its good points. It directs NASA to make use of commercial launch vehicles to “fulfill appropriate mission needs, including the support of low-Earth orbit and lunar operations.” When a viable commercial capability exists, the government should use it, not compete with private industry. Congress could go further and require NASA to use microgravity services available aboard commercially owned aircraft rather than operating its own aircraft for that purpose.

The bill directs NASA to ensure the CEV is capable of transporting six passengers and to develop autonomous rendezvous and docking technology, which would aid not only NASA vehicles but also some of the private vehicles that are being developed to take cargo to the space station.

The bill also authorizes NASA to hold competitions to foster the development of new technology and make cash awards totaling as much as $50 million in a single year. It is a great idea that also should be funded.

The subcommittee also did the right thing by rejecting a proposed amendment that would have established funding minimums for aeronautics research, solar probes and planet-finding programs.

Like many of their colleagues, Sens. Hutchison and Nelson have been strong supporters of NASA and its new administrator. They should do everything they can to give him the tools he needs to turn the agency around, but the bill needs to be amended in conference to make sure it does not tie his hands.