A nuclear asteroid deflection can vary nearly fivefold by which side is hit

A Sandia National Laboratories team reports in Icarus new simulations of how nuclear-blast X-rays heat an asteroid's surface, eject material and push its orbit when the object has a realistic irregular shape. Irradiating one side of the same simulated asteroid changed linear velocity by 3.9 millimeters per second; another side produced only 0.8 millimeters per second, a nearly fivefold difference. For another object, the spin change varied by a factor of 17 with direction. A new algorithm ran more than 1,600 times faster than the old model, allowing full-scale complex surfaces. The result is not mission approval for “nuking an asteroid”; it says defenders must first measure 3D shape, orientation and material before choosing aim point and lead time.