WASHINGTON -- An international planetary defense force to fend off threatening comets and asteroids. Space traffic control to avoid spacecraft run-ins with Earth orbiting junk. Establishing an inter-linked, all-for-one, global navigation satellite system.

These were a few of the thorny issues tackled by a world-class brain trust of space experts. The cadre of officials divided up into various working groups.

Their soon-to-be issued report comes to a general consensus: A shakeout is needed regarding how 21^st century international cooperation in space is promoted, initiated, and carried to fruition.

The report, International Space Cooperation: Addressing Challenges of the New Millennium, is based on the deliberations of nearly 80 experts from 17 nations and three multinational organizations. The group met last March in Seville, Spain for three and a half days of intense discussions.

A worrisome issue for the new millennium is dealing with the "real and credible threat" of future impacts on Earth of asteroids and comets, the report notes. "Whereas the probability of an impact is low, such an event could cause a global catastrophe for all living things on the planet. The threat therefore warrants serious and immediate attention," the experts advise.

The working group on Earth-threatening asteroids and comets stressed that:

• Current detection efforts to spot, catalog, and keep and eye on are inadequate, limited, poorly funded, and not conducted in a coordinated manner;
• The general public and government decision-makers are poorly informed on the nature and seriousness of the threat;
• An international study should be initiated on how the world's space prowess, properly augmented with interceptors and other devices, might be used to counter any near-term comet or asteroid threat. In the long term, a dedicated International Planetary Defense System may be in the offing;
• Any planetary defense system "should deflect rather than fragment" an incoming near Earth object. However, the option of using nuclear devices "must be preserved", as they are probably the only effective option for very large bodies or those for which little warning time is available.

An international approach to detecting Earth-threatening asteroids and comets and responding to the threat they pose, the working group recommended, can be best served through an "effective executive body" operated under the auspices of the United Nations.

Keeping a sharp eye on the sky is mandatory.

Along with augmenting ground-based sensor abilities in both northern and southern hemispheres here on Earth, space-based systems are required, the working group noted.

One possibility: A large infrared space-based telescope stationed at the L2 Lagrangian point - a special locale distant from our planet. From this site, an observatory could spot objects that are otherwise extremely hard to detect here on Earth.

Also deemed important, is for the lofting of more rendezvous, landing, and sampling space probes to comets and asteroids. There is a continuing need to fully understand the inner and outer makeup of cosmic interlopers, the group stated.

The space experts concede that there exists a "giggle factor" associated with asteroid and comet impacts. Movies and television may partly be one reason for this. On the other hand, another factor might be in play too.

A "psychological denial that such improbable events could actually happen to us or our children," might be at work as well, the study group said.

"I consider the report of the working group the most comprehensive paper ever produced regarding near Earth object policy issues, to be further developed at [a] world-wide level," said Hans Haubold of the UN Outer Space Office in Vienna, Austria, who co-chaired the gathering.