I got a call yesterday from a producer at Fox News, who asked me if I wanted to comment on a proposal by two California physicists to build a "Death Star" that would protect our planet from incoming asteroids. The answer to a question like that is inevitably going to be "Of course!" so I appeared on Fox News earlier this morning to discuss the idea. (View the story here.)
Conceptual illustration shows how DE-STAR could vaporize an asteroid and power a space probe at the same time...if we could ever build such a thing. (Credit: Philip M. Lubin) The proposal, which was announced by press release and press conference, comes from cosmologist Philip Lubin of the University of California at Santa Barbara and engineer Gary Hughes of California Polytechnic State University. Calling it a Death Star immediately makes the idea sound both sexy and goofy. The researchers use the term Directed Energy Solar Targeting of Asteroids and exploRation (DE-STAR), which isn't much better. Setting aside the name, though, the idea is interesting. Lubin and Hughes envision building a scalable, phased array, space-based laser system, powered by large solar panels. Solar power is abundant and uninterrupted in space; developing large, lightweight photovoltaic arrays would be a useful technology for future space stations or power-hungry scientific experiments. Laser beams could be useful for characterizing the composition of near-earth asteroids, and for conducting experiments on how laser heating or laser vaporization could alter an asteroid's orbit. And phased arrays are an intriguing way to create a steerable light beam from a flat surface without turning it. DE-STAR begins to look less convincing when you consider the scale of what Lubin and Hughes are proposing. The scientists speculate loosely about a 10-kilometer wide DE-STAR 4 capable of vaporizing a 500-meter-wide asteroid in about one year. Such a device is well beyond the capability of today's engineering and space infrastructure, and its cost would certainly be in the hundreds of billions of dollars, if not more (Lubin and Hughes did not discuss budget). Space-based lasers obviously would have enormous military value, raising delicate political concerns and violating current treaties. At any rate, talking about Death Stars is fun but the really meaningful challenge is finding a way to build a technology test bed to see if the DE-STAR concept makes sense. There are many other promising suggestions of how to deflect an Earth-approaching asteroid. Whacking it with a kinectic impactor, pulling it with a heavy mass (aka "gravity tractor"), attaching a rocket to the surface, or even painting or covering the asteroid to alter the push of solar radiation all might prove more cost-effective. The old blast-it-with-a-nuke approach could work as well, though the goal would be to alter the asteroid's course, not to disintegrate it. For any deflection scheme, the single biggest obstacle is that we currently cannot detect small asteroids before they hit. The Russians had exactly zero warning that a meteor was incoming over Chelyabinsk. NASA's funding in this area is puny, as I posted earlier. Or as I mentioned on Fox News, the total federal spending on asteroid detection is about 1/5th of the free postage budget allocated to Congress every year. That's an easy statistic to harp on, since everybody loves bashing Congress. The real point is that early detection is both fairly cheap and an essential preliminary step before anybody starts building an expensive, complicated asteroid defense. Companies like the B612 Foundation, Deep Space Industries, and Planetary Resources have plans to build private detection networks. But why is our government walking away from such a low-cost, high-payoff, and universally useful task?
