NASA’s March report to Congress on deflecting Near-Earth Objects offers some startling assessments. Specifically, the report says this: “Nuclear standoff explosions are assessed to be 10-100 times more effective than the non-nuclear alternatives analyzed in this study. Other techniques involving the surface or subsurface use of nuclear explosives may be more efficient, but they run an increased risk of fracturing the target NEO. They also carry higher development and operations risks.”
Fair enough re setting off a nuke on the surface of an asteroid. But aren’t we jumping the gun on other nuclear options when alternatives seem available? That’s certainly the view of Rusty Schweickart, founder of the B612 Foundation, which is all about spreading the word on the threat these objects may pose to Earth. Alan Boyle discussed these matters with Schweickart in a recent post, from which this on the non-nuclear option:
Schweickart argues that the so-called “nuclear standoff” option should be used only as a last resort. He contends that 98 percent of the potential threats can be mitigated by using less extreme measures. For example, he favors the development of a “gravity tractor” – a spacecraft that would hover near an asteroid for years at a time, using subtle gravitational attraction to draw the space rock out of a worrisome path.
To kick it up a notch, Schweickart said a threatening NEO could first be hit with a kinetic impactor – say, a scaled-up version of the Deep Impact bullet that hit Comet Tempel 1 back in 2005 – and then the orbital track could be fine-tuned using the tractor. Navigational sensors aboard the tractor would check to make sure the NEO was on a completely safe path.
“This combination is obviously the way to go,” he said.
We’ve got to get this issue straightened out, because we still don’t know how much of a threat really exists from these objects. That makes the NEO hunt a key part of future space strategy. Schweickart discusses an infrared telescope in an inner-Solar System orbit as one way to get the job done, but read the rest of Boyle’s post for the details, and note the continuing analysis of 99942 Apophis, whose orbital wanderings may ratchet up public awareness of potential impactors once again.