CIENTISTS have warned of the theoretical hazards of wayward asteroids and comets. Jupiter's encounter with the real thing brings those warnings into focus.
It also gives a sense of reality to legislation voted by the House Committee on Science, Space, and Technology for dealing with the possible danger. If passed by the full Congress, this would direct the National Aeronautics and Space Administration to submit a plan by next February for a 10-year program to catalog ``all comets and asteroids that are greater than one kilometer [0.6 miles] in diameter'' traveling along orbits that intersect that of the earth. It would make military space-surveillance equipment available for the survey. Other nations would be invited to share the work.
This is a sensible and inexpensive scheme. More than two years ago, a NASA workshop authorized by Congress determined that a global network of six telescopes, each with mirrors two to three meters in diameter, would be sufficient to build the catalog. Such telescopes should cost $6 million to $8 million apiece.
Unfortunately, this recommendation was overshadowed by a companion study of ways to defend Earth from cosmic missiles. Critics dismissed its schemes for using high-powered rockets and nuclear explosives as welfare for the weapons industry. That gave the entire subject of asteroid-comet danger a bad name.
The House committee is wise to revisit the issue. The Jovian impacts have validated theoretical estimates of a moderate-size asteroid's punch. The likelihood of a collision between Earth and an object a kilometer wide or larger is very low. But scientists have not exaggerated the catastrophic damage it would cause. Much of the human species, along with many other species, would be destroyed if Earth took the kind of pounding Jupiter endured. It is only prudent to identify objects that will cross Earth's orbit and see if any pose a danger.
There is no need for a standby asteroid defense system. A well-planned surveillance network should spot potential colliders several years - even decades - in advance. There would be plenty of time to decide how to deal with them.
Congress should enact its committee's legislation. If NASA then submits a sound action plan, Congress should fund that too. The money spent would be both an insurance premium and an investment that generates new knowledge of the solar system.