If you believe Hollywood it’s easy to deal with an asteroid heading for Earth: simply blow it up with nuclear weapons. In practice that’s unadvisable, since shattering an asteroid, even if it was possible, would leave a large number of small bodies still on collision courses: in essence replacing a single bullet with a shotgun blast. This week in southern California attendees of the AIAA 2004 Planetary Defense Conference: Protecting Earth from Asteroids will discuss various alternative techniques that could be used divert an asteroid or comet. One concept, the Atlanta Journal-Constitution reports, is called Modular Asteroid Deflection Mission Ejector Nodes, or MADMEN. The concept is simple in design: construct a large number of small spacecraft that would fly to and land on a threatening asteroid, then drill into it and hurl away chunks of rock. The force that each ejected rock fragment would impart on the asteroid would be small, but multiplied by hundreds of spacecraft, and carried out over a long period of time, it would be enough to nudge the asteroid’s orbit just enough to prevent a collision with the Earth. MADMEN is only at the conceptual stage, with no plans by NASA or the Defense Department to actually fund the development of actual hardware for this or other projects.