The President articulated the obvious -- a space program has to go somewhere. His redirection of NASA back to the Moon in 15 to 20 years, then on to Mars, comes with both a timeline and cost reasonable in this environment.

However, ambiguities in his speech, such as omitting references to permanent lunar settlements, NASA's subsequent "Exploration Requirements" focusing on

Mars and the media's preoccupation with the glamour of a Mars mission a quarter-century away, have muddled the vision.

All those factors have made it seem as if all the unknown long-term costs of going to Mars must be addressed near-term, confusing a Congress that has to implement the redirection. Those factors also have increased the risk that even after expending billions of dollars, we may be left 25 years from now with but one or two flags-and-footprints missions to Mars and no permanent beachhead on either the Moon or Mars.

Consequently, the priority of the space community must be bringing the Moon-Mars focus back to the near-term. The focus must be on programs that proceed in stages, each with its own perceivable goal and associated cost estimates. Because those estimates will be near-term they will be easier for Congress to ascertain and periodically review. Staged, ratchet-like programs also ensure that infrastructure is left in place should there be any pause or reduction in funding.

To create that permanent beachhead, we must focus on the Moon. The Moon can be reached; the base there can grow incrementally and return benefits -- all in a more conceivable time frame. The most attractive feature of making the Moon the first permanent off-world human outpost is its proximity to Earth. The

Moon is close, a couple of days away; Mars is many months farther.

That proximity has many advantages. As far less rocket power is required to reach the Moon than is required for Mars, larger payloads can be sent or smaller, more affordable vehicles can be used.

Close proximity means more frequent trips, more people sent, and infrastructure more quickly established. Because of the shorter trip times, a focus on the Moon also is less risky than Mars. There is continuous access to a lunar outpost, whereas Mars is reasonably accessible only once every two years. With unexpected discoveries or dangers, new equipment or scientific instruments can be sent from Earth to the Moon relatively quickly.

A growing lunar facility would enable, decades sooner than a Mars base, a long list of desirable outcomes:

• Lunar Resources: Finding, mining and developing the techniques to use local resources (including energy, oxygen and metals) to evolve toward self-sufficiency and produce fuels to reduce the cost of space operations.

• Off-Earth Industrial Base: Development of infrastructure and test facilities to support the industrialization / commercialization of space and exploration of the solar system.

• Visibility: A lunar base overhead every night would provide a tangible reminder of our space achievements and an inspiration to further progress.

In addition, space tourism is more likely to develop quickly with a nearby destination like the Moon.

A Moon base also would provide a low-gravity, isolated, stable, vacuum environment with no magnetic field. Such an environment makes it possible to conduct cutting edge physics research, including nuclear materials experiments we might prefer done off-planet, medical and geriatric research, biological and genetic investigations that might be dangerous to conduct on Earth and astronomy from the far side of the Moon.

The Moon phase of the Moon-Mars Initiative can be done in digestible steps that can, as funding or interest fluctuates, be speeded up or slowed down with less risk of total cancellation than a Mars-oriented program.

An early module could be a habitation module, allowing extended crew stays. Later deliveries could be rovers, building cranes, mining equipment, kilns for metallurgy, telescopes for astronomy, medical labs and other scientific modules, and more habitation modules. This staging would allow for both short visits by scientific specialists and the gradual building of a permanent outpost.

All these activities on the Moon will set the stage a quarter-century from now for continuing on to Mars. By then we will have developed vastly improved propulsion technologies, greater experiences working in space and on other worlds, better technology for harsh off-world climates and a space infrastructure with many startup costs amortized, so that the incremental cost of taking that long next step to Mars would be much less daunting.

Most of all, unlike after Apollo, we will have established a beachhead in space from which there can be no retreat.

Jeffrey Liss is a Senior Vice President of the National Space Society.