The release of NASA’s budget last week seemed to confirm what has long been clear to everyone. The ambition to return to the moon via the Constellation program is  not a realistic goal.

The administration’s proposal reflects a change of course based on the recommendations of a report by a blue ribbon panel. The Augustine commission advised President Obama last fall to re-evaluate NASA’s $100 billion approach to space exploration.

The new federal budget makes it clear that the Constellation program will never get off the ground. It scraps plans to develop two Ares rockets and an Orion crew capsule for space exploration, investing billions instead in rocket science and other research.

It’s a disappointing reality: We can’t afford the 2003 vision of a return to the moon as a first step toward Mars, relying on the same program as well for transportation to the International Space Station. Obama’s new approach relies on NASA and private companies to come up with new approaches to space exploration.

It will be a difficult challenge, but NASA’s engineers and scientists are capable of devising more flexible and less expensive strategies for venturing into space. And it strikes us as logical to separate this quest from a short-term problem: How to carry astronauts to the international space station and other destinations in low earth orbit.

Private companies, spurred by an interest in federal contracts, will pursue development of low-cost commercial rockets for this purpose. American free enterprise is adept at finding cost-effective solutions to difficult technical problems, and the Obama budget devotes billions towards this goal.

The budget also calls for a substantially increased investment in earth science research, using satellites to monitor global warming and carbon levels in the atmosphere, among other things. And it extends funding for international scientific collaboration in space, extending Space Station funding until 2020.

The abrupt end of the Constellation program may be wrenching, especially to companies and communities that have depended on the program for high quality jobs. In those areas, the argument that the new approach will eventually create jobs is small comfort. But new challenges and new approaches are likely to bring breakthroughs that we cannot anticipate.

The White House plan sets out without a specific space objective. The general goal is to develop technology ”“ spacecraft, orbiting fuel depots and robotics ”“ that can serve a variety of missions. This “Flexible Path” seems to be the best route to Mars, and to other destinations.