Deflecting an Asteroid Threat

Movies like to portray the ultimate defense against an asteroid threatening life on planet Earth as a nuclear weapon tipped missile. This makes little sense. We think of our Inter Continental Ballistic Missiles (ICBM) as being long range because they are compared to most of our other weapon systems. But in the sense of interplanetary affairs they are short range. Our ballistic missiles are designed to move high above the planet and then fall back onto a target. Most of them don’t have the ability to maneuver much at all and don’t carry enough fuel to leave Earth. The Saturn V missile that sent Apollo astronauts to the Moon dwarfs ICBMs and was a three stage rocket.

For rocks smaller than a few thousand meters in diameter, destroying them with a nuclear blast may be practical. But there are many unknowns about how the blast will affect the rock and what the result will be. If the blast shatters the rock into many pieces but does not destroy them, the threat to Earth may actually be magnified. For rocks larger than several thousand meters, multiple blasts would probably be needed. Again, this depends on the composition of the rock and the outcome still might be uncertain.

A much simpler strategy is to deflect the incoming asteroid while it is still far enough away to be moved gradually using much smaller amounts of force than a nuclear weapon. An impact strategy can be applied like one billiard ball striking another. Another strategy would be to apply a steady supply of force from a rocket engine that is attached to the asteroid. In any case, deflection strategies are made more effective and require less force if they are applied while the rock threat is still at a great distance from us.

The deflection at a distance strategy would work best by deploying a defensive network at a distance from Earth well before any threat is detected. This would allow deflection agents (of any type) to intercept the threat and deal with it while it is still far away. Creating this defensive network would be expensive when considered by itself. But if mankind is to continue advancing out into the Solar System, we’ll be going there anyway and will need navigation and communication systems across the areas we explore. At the same time as we deploy these systems, they can incorporate sensors that will provide early warning and they could also be integrated with some form of deflection agent.

Comments are closed.