HOUSTON -- The International Academy of Astronautics presented its outline for a 50-year exploration program here Oct. 13. The plan features robotic missions and human habitation of the moon and, eventually, Mars, the examination of near-Earth asteroids and the construction of large telescopes to scan space for Earth-like planets.

In an interim report on its "Next Steps in Exploring Space" study, to be completed in October 2003, IAA officials said the most important breakthrough for the endeavor is not technology but a better exploitation of the public's inherent interest in space exploration.

Public interest here at WSC, at least, was evident. IAA officials outlined their program to a standing-room-only ballroom audience that appeared not to mind the Sunday 9 a.m. schedule.

Wesley T. Huntress, a former NASA associate director for science and the director of the IAA study, said today's space program lacks a direction that can attract the public. The main problem, he said, is that NASA and the world's other space agencies have no target destination.

IAA is proposing one. It includes placing huge telescopes into space at points further out than low Earth orbit but close enough to be accessible by astronauts for servicing. Near-Earth asteroids would be examined, and possibly mined for minerals and used to test materials needed for Mars exploration. The moon would become a robotic colony, and perhaps would serve as a base for a small group of astronauts conducting science.

And finally, there is Mars, "the ultimate destination of this study," Huntress said. "Water is the key, the thread."

The challenges are daunting. Nuclear-powered spacecraft almost certainly will be needed, and a new deep-space shuttle as well. But tapping latent public enthusiasm is the indispensable ingredient that may be just as challenging.

"What is clear is that none of this will happen if we go on as we are, with astronauts doing nothing more than zero-g tumbles in low Earth orbit," Huntress said.