Nuclear weapons could be used to stop earth-bound asteroids, but in most instances, they are not the best option, said Apollo astronaut Rusty Schweickart during a public lecture this Wednesday in San Francisco.

The venerable scientist explained that all but the largest heavenly bodies can be redirected by rear-ending or towing them with an unmanned spacecraft. But last year, NASA issued a report stating that using nukes is the best strategy to prevent a catastrophic collision with earth.

Although Schweickart has a great deal of faith in the agency, enough to risk his life piloting their lunar lander, he feels that they issued the misleading statement – under immense political pressure. It was a nefarious excuse to put nuclear weapons in space.

His own organization, the B612 Foundation, intends to use gentler tactics to alter the course of an asteroid by 2015.

Right now, humans are not tracking most of the objects that could cause serious damage to earth, but in the next century, as powerful new telescopes come online, we will begin watching many of them. When that day comes, we will know which ones stand a chance of hitting earth, and it will be time to make some tough decisions.

Since tracking asteroids contains an element of uncertainty, there will be a lot of false alarms, so it may not be necessary to take action at all. If it must be stopped, should we bump it, drag it, or blow it off course?

The astronaut compares our current situation to standing blindfolded in a batting cage. Right now, we can't do anything, but we know that some balls are hurling towards us. In a few years, our blindfold will come off, and the whole world will be forced to decide – together – when to duck.

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Image: Don Davis / NASA Photo: Jessica Culler