Marginal Utility

by Tom Bozzo

A cool item in the Washington Post describes a new method for deflecting potential killer asteroids, published in Nature by a pair of NASA astronauts. (One of the co-authors, Edward Lu, happens to be an astrophysicist.) A relatively massive spacecraft — around 20 tons; large interplanetary probes such as Galileo and Cassini have fueled masses of a few tons — would rendezvous with an asteroid, then maneuver to use its gravitational pull to impart a very small velocity change on the asteroid. Over the times and distances involved, that would be sufficient to convert a hit to a miss without mucking about with nuclear weapons and/or trying to land on tumbling asteroids a la "Armageddon." This is important as there is a known asteroid that will come incredibly close to Earth in 2029 and may hit us in 2036.

The concept spacecraft would be propelled by a nuclear-electric (ion) drive, which would be able to impart a large velocity change on the spacecraft without requiring it to carry enormous amounts of chemical rocket fuel that would, among other things, strain if not vastly exceed existing construction and launch technologies. (Lower-powered solar-electric xenon ion drives have seen some applications on inner Solar System research probes and commercial satellites.) The traditional catch has been that anti-nuclear activists have opposed launching nuclear reactors into space, partly due to the possibility of terrestrial contamination in the event of a launch accident, and partly due to concerns over military applications of the technology. An impact from a 300-meter-plus asteroid would be a calamity of sufficient magnitude as to outweigh such concerns.

Now, the Bush administration had actually given nuclear-electric propulsion a shot in the arm via the Prometheus project, part of the Bush space exploration "vision" as recently as last year. After all, the Bushies are not likely to take dictation from anti-nuclear environmentalists.

But surely there must be a Bush administration incompetence angle. You betcha! The Mission to Gut the NASA Budget has reportedly extended to Prometheus; per the Post:

...research on nuclear-powered space vehicles has been cut dramatically to help fund President Bush's initiative to send humans to the moon and Mars.

Such foresight from our fearless leader! This is an area where a few billion dollars' worth of prevention are worth a few trillion (or more) of cure.


(Title reference here.)