Killer comets and cosmic catastrophes

There are small issues regarding public safety: the concern for the safe use of firecrackers is one of them. And there are some big issues, for example, those that involve threats to the very existence of humanity. One such threat is astronomical: one comet or asteroid could destroy all human life. It just has to have sufficient mass and hit Earth almost anywhere.

A giant impact could happen in the next few years or the next several million. Nobody yet knows when such a disaster will occur. But most astronomers think an impact is inevitable, because our planet, like others, is a target in a cosmic shooting gallery. Things are flying about in the solar system, and the probability that collisions will eventually occur here is extremely high. A big body will sock our planet and disrupt the geological and meteorological processes that we have come to regard as normal. Homo sapiens may have become extinct before this happens, but if a giant impact occurs while humans still inhabit this world, conditions that develop may threaten the survival of our species, if they do not end it outright.

Many theorists have argued that the extinction of the dinosaurs resulted from conditions produced by an asteroid or comet when it collided with Earth at the transition from the Cretaceous to the Paleogene period, about 65 million years ago. And the most credible explanations of the Tunguska Event of 1908 involve hypotheses that an extraterrestrial body striking our atmosphere created the devastating blast that some witnesses thought signaled the beginning of the end of the world.

We are prudent to think about the matter. But since the experts cannot point to an immediate threat, motivating our legislators to fund a massive search for big bodies on collision courses with Earth, and to fund the development of technologies for neutralizing such threats, will be difficult. The Federal budget is gargantuan. But getting our government to spend more money, especially now, at a very difficult time for our economy, for solutions to problems that may not materialize before the successors to humans start worrying about these things, may be impossible.

Nevertheless, some work is underway. NASA reports that up to July 1, 2010, observers have detected 7136 Near-Earth Objects (NEOs). The NASA Near Earth Object Program aims to "detect, track and characterize potentially hazardous asteroids and comets that could approach the Earth." (http://neo.jpl.nasa.gov/faq/#purpose) And some scientists have already considered a few ways to prevent giant impacts. (The most effective will probably not involve nuclear weapons.)

Some well-educated amateurs can help. They can track some NEOs already identified. Good telescopes require a substantial investment, but many people can afford them. Just as important as having a telescope of sufficient power, however, is the commitment to spending considerable amounts of time capturing and analyzing images.

A giant impact is one of the greatest threats to our civilization; it is surely one of the quickest ways that life on Earth could end. But since we have no idea when the threat will materialize, directing scarce resources toward effective solutions is very challenging. Even so, at the very least, observers ought to continue their efforts to detect the astronomical objects that might threaten our survival. And researchers, at the very least, ought to continue to develop ways for averting collisions with bodies when they are finally discovered to be headed our way. Yet much more work needs to be done. Redoubling our efforts is not just a good idea: our lives may someday depend on it.