There is cause for serious concern in U.S. President Barack Obama’s 2011 budget request for NASA, which points the agency’s human spaceflight program in a direction that at least two U.S. lawmakers described as a radical departure from previous plans, five years in the making, to replace the space shuttle and return astronauts to the Moon.

The good news is that NASA, unlike many other U.S. federal agencies, is slated for a 1.5 percent funding increase next year, to $19 billion. Also on the positive side of the ledger is a commitment to support the international space station at least through 2020 and to provide a significant funding boost over the next several years for science, particularly in the area of climate monitoring.

But the White House has slammed the door on a strategic initiative hatched by the previous administration — and endorsed by Congress in two separate NASA authorization bills — to get U.S. astronauts out of low Earth orbit, where they have been confined since the Apollo program ended in 1972. U.S. taxpayers since 2005 have invested some $9 billion in the now-doomed Constellation program, mostly on the Orion crew capsule and its Ares 1 launcher. Those vehicles were intended to replace the space shuttle fleet, which is to be retired in the next year or so, and later to launch Moon-bound astronaut crews.

The cancellation of Ares 1 had been widely anticipated, especially after an independent panel concluded this past summer that NASA could save time and money by relying on commercially developed vehicles to ferry astronaut crews to and from the space station. But few thought the administration would detonate the entire Constellation program — including Orion and the Ares 5 heavy-lift rocket. Those vehicles, or something like them, will be needed to get astronauts to destinations beyond low Earth orbit. So while the White House can say it has a plan for space station crew transport — the budget allocates $6 billion over five years to develop commercial space taxi services — it has a long way to go to answer the question of what comes next for NASA’s human spaceflight program.

Administration officials have implied that Constellation was undone by poor management and bad technical choices, but there’s little evidence to support that. Former Lockheed Martin chief Norm Augustine, who chaired the panel tasked last year to review NASA’s human spaceflight plans, said the program would likely succeed given enough time and money.

The problem was that Ares 1 was not going to be finished before its only near-term destination, the international space station, was slated to be deorbited thanks to a budget omission that everyone knew about but did nothing to fix until it was too late.

The panel effectively presented the White House with two choices: Kill Ares 1, or walk away from the space station in 2015, a nonstarter if NASA is to ever lead another big international project.

Scrapping Orion and Ares 5, however, goes beyond Augustine’s recommendations, leaving NASA with no discernible plan for what the panel characterized as meaningful exploration.

Seeking to dispel the notion that the United States has written off manned missions to deep space, NASA officials said the budget request commits significant sums of money — notably, in the years following 2011 — to developing breakthrough technologies that they said will revolutionize space travel.

This is not reassuring. In the decade before 2004, when NASA was handed its now-defunct mandate to return to the Moon in preparation for missions to Mars, the agency poured billions of dollars into high-profile technology development programs, including the X-33 reusable rocket, the Space Launch Initiative and the Project Prometheus nuclear power and propulsion effort. All were aimed at developing game-changing technologies for space exploration; all went nowhere.

Open-ended technology programs keep contractors busy, and that’s not to be completely dismissed at a time of legitimate concerns about the erosion of the U.S. space industrial base, propulsion being a prime example. But since they are not tied to specific mission requirements and milestones, their budgets invariably get raided, not only by NASA managers seeking to bail out troubled programs, but also by lawmakers with pet projects to feed. The most useful innovations tend to be developed in response to specific mission requirements; history shows that pushing technology in hopes that a future application will reveal itself is more likely than not to waste money.

In its landmark report that gave impetus to the Constellation program, the Columbia Accident Investigation Board (CAIB) warned against betting on breakthrough technologies to field a next-generation space transportation system.

The White House, with its plan to rely on the private sector to deliver astronauts to  orbit, cannot be accused of that. But it is taking a different kind of gamble, one that assumes industry, freed from onerous NASA oversight, will come up with a system that costs less and flies sooner without compromising safety. This seems at odds with a key point made by the CAIB: Crew safety should hold absolute sway over competing priorities like lower costs and reusability.

There is no reason to believe that U.S. industry — which lest anyone forget includes highly experienced NASA contractors like Boeing and Lockheed Martin — with proper financing, cannot come up with an alternative means for getting astronauts to and from the space station. But given the fundamental responsibility NASA and its contractors have to ensure astronaut safety to the greatest extent possible, any commercial taxi service is bound to cost a lot more and take longer to field than its proponents would have everyone believe.

Whatever the merits of the commercial strategy, what the White House has done here is throw NASA back to square one in its long-overdue space shuttle replacement effort, continuing a pattern that has spanned several administrations and produced nothing. Some lawmakers have vowed to save Constellation, but any rear-guard action is probably futile and could wind up extending the U.S. human spaceflight hiatus.

Instead, Congress should give the commercial strategy a chance to succeed. At the same time, NASA’s congressional stakeholders must insist that the administration identify specific post-space station exploration goals — a mission to an asteroid, for example — and come up with a realistic and funded development program for achieving them. What the president has offered so far has the look, feel and smell of a dead-end vision that maximizes the risk and minimizes the potential reward of human spaceflight.