U.S. lawmakers seeking more funding for programs they believe are being shortchanged in NASA’s 2013 budget request should not view the agency’s Commercial Crew Program as their cash cow. Unless, of course, their goal is to lengthen the period during which the United States is dependent on Russia to ferry astronaut crews to and from the international space station.

During separate hearings in March, Rep. Frank Wolf (R-Va.), who chairs the House Appropriations subcommittee that funds NASA, and Sen. Kay Bailey Hutchison (R-Texas) suggested that narrowing the field of commercial crew competitors sooner than the agency plans would free up 2013 funding that could be redirected to robotic planetary exploration and to the heavy-lift Space Launch System (SLS) and Orion deep-space capsule, respectively. Wolf asked about the feasibility of merging the proposals of companies competing to provide crew taxi services into a single “all for one and one for all” project.

Nobody was thrilled with NASA’s 2013 budget request, but it’s a bit easier to sympathize with Wolf’s desire to beef up the planetary program, which was hit especially hard. Not only was NASA forced to bow out of the cooperative ExoMars mission with the Europeans — at considerable expense to its reputation as a partner in international projects — there is nothing solid on the agency’s planetary exploration horizon beyond the Osiris-Rex asteroid sample-return mission in 2016 and a Discovery probe currently in the selection process.

Sen. Hutchison’s complaint is that the nearly $3 billion allocated between SLS and Orion next year falls short of what Congress called for in the NASA Authorization Act of 2010. This is true, of course, but that legislation hardly reflects current budgetary realities; it calls for nearly $20 billion in total funding for NASA next year, which is about as likely as getting blood from a stone.

NASA has no firm destination for the hugely expensive SLS/Orion combo, which isn’t expected to make its crewed debut before 2021. Moreover, it is far from clear that the agency can afford the other systems that will be needed to carry out meaningful deep-space exploration missions.

If the United States intends to send astronauts beyond low Earth orbit some day, it obviously will need a heavy-lift rocket and accompanying crew capsule. But short of a major shift in U.S. national priorities, and a budget to match, the time urgency for fielding these vehicles just isn’t there.

The Commercial Crew Program, meanwhile, offers the only near-term hope of restoring independent U.S. crew access to space. NASA officials believe a commercial taxi service to the space station could be available by 2017. Space development programs rarely stay on schedule so that timetable might be a bit ambitious even assuming full funding, but the same holds true for SLS and Orion. What’s difficult to dispute with any credibility is that commercial crew services will not be available on the current schedule if the program’s 2013 budget is milked.

It is plausible that merging elements of the various commercial crew concepts being developed, as Wolf suggested, would reduce costs. One could imagine, for example, pairing a crew-carrying variant of Space Exploration Technologies Corp.’s Dragon cargo capsule, which has made one successful test flight to date atop the company’s fledgling Falcon 9 rocket, with United Launch Alliance’s Atlas 5, a rocket with an extensive track record of success.

Those companies are of course free to join forces, but if they prefer not to, the government can hardly impose such a solution — or any solution, for that matter — in a commercial procurement. Further, there is no guarantee that pairing Dragon and Atlas 5 — assuming that’s even feasible — would translate into sufficient commercial crew savings to make a difference, in 2013, on the planetary or SLS/Orion programs. A couple of hundred million dollars is a relatively small percentage of the SLS/Orion budget and NASA has yet to define a planetary exploration campaign in the wake of its ExoMars exit.

Sen. Hutchison argued that NASA should reduce the number of commercial crew competitors, ostensibly by selecting a winner sooner than currently planned. That’s also worth exploring. The notion that the market can sustain two operational crew transport providers simply isn’t realistic, and while an extended competition would enable NASA to select a winner with more confidence, the agency might not have that luxury.

The problem is, not enough is known about the potential cost-cutting alternatives to NASA’s current commercial crew strategy to make a strong case for shifting some the program’s proposed 2013 funding to Mars exploration or SLS/Orion. Doing so is far less likely to make a positive impact on robotic planetary or deep-space human exploration than it is to merely extend the time during which NASA funds for space station crew transport must be spent in Russia.