Researchers at Sandia National Laboratories have developed a method to make asteroid deflection modeling faster and more detailed. Their simulations also demonstrated just how much asteroid shape and orientation can complicate efforts to deflect a threatening space rock. Sandia researchers, led by staff physicist Nathan Moore, were looking for a way to better model how X-rays from a nuclear detonation near an asteroid can change its trajectory, as explained in a recently published research paper . “Before, the calculations were so time-consuming, one could not do very many of them,” Moore told The Register . “So it was very difficult to explore different scenarios, different asteroids, or different mission concepts.” The complexity of those calculations forced earlier researchers to make compromises, often modeling asteroids as spheres or simplifying the physics involved. Perfectly spherical asteroids are rare, and their irregular shapes present an additional challenge for those keeping an eye on the skies to avert a potential asteroid apocalypse. To overcome the computational problem and enable better modeling of irregular asteroid shapes, Moore and his team combined two high-fidelity simulation codes already in use at Sandia: ALEGRA, which models radiation heating and high-energy material dynamics, and SPARTA, which simulates the behavior of low-density gases. As Moore explained to us in an email, both codes are good at one particular part of asteroid impact modeling, but bad at the other. “ALEGRA … can very accurately simulate the vaporization of the rocky surface, but the calculation becomes more inefficient for matter at low densities,” Moore told us. “This is a problem for asteroid deflection simulations, because as the gas expands around the asteroid, the calculation time goes up.” Earlier asteroid simulations using ALEGRA typically modeled asteroids as spheres to reduce calculation times. “SPARTA is more efficient at low gas densities,” Moore said. “The problem is, conversely, SPARTA gets more difficult to run at high gas densities. So the key here was using both codes.”…