President Bush's plan to steer NASA towards the Moon and Mars is, for now, more talk than action. The lunar landings, and most of the spending, will come long after he leaves office. Let's accept that his motives go beyond election-year grandstanding, however. Did he make the right decision?

Yes, with reservations. Having decided correctly to ground the shuttle and scale back investment on the space station, Bush chose — probably with an eye on US public opinion — to keep sending astronauts into space. The alternative was to cut NASA back to being a research-only agency. Scientists were fooling themselves if they thought that the money saved from the space shuttle would go on space telescopes. It would simply have disappeared.

The Moon is a useful, nearby place to find out whether human spaceflight still has a viable future. Arguments based on destiny or the 'human spirit' only go so far. In the end, astronauts need something to do out there. A small, 'tended' (rather than permanently occupied) lunar base can help settle the old, but never fully resolved, debate over sending humans or robots into space. The two will work together at first, just as in a modern factory on Earth. We can hope that NASA's twenty-first-century lunar exploration will advance the science of telerobotics in a meaningful way. If astronauts and machines are assigned work based solely on their merits and cost-effectiveness, we may see human visits to the base become less frequent as engineers learn to achieve the same tasks remotely. This evolution could be one of the new Moon programme's most valuable products, and could change the way we approach Mars exploration. Maybe when the time comes to send humans to Mars, we'll find that we don't need to.

But to reach that point, NASA should not prejudice the new Moon programme to favour astronauts over their robotic assistants. This will require clarity of purpose and honest decisions about engineering and funding priorities. Bush's plan calls on NASA to reinvent itself and break some ingrained bad habits. A tall order, but a good one.