A key challenge in asteroid-deflection modeling is predicting how an irregular body will respond to a proposed intervention. Simulations of Golevka, Bennu and Itokawa found that targeting different sides of the same asteroid could produce as much as a fivefold difference in velocity change, The Register reported. The study was led by Sandia physicist Nathan Moore and published in Icarus, according to KRQE.
A prediction, not a mission test
The findings are predictions from computer simulations, not results of a deflection attempt on an actual asteroid. As Newswise reported, the model represents rocks breaking up at the surface but cannot yet reliably determine whether the whole asteroid would fracture. That leaves an important uncertainty: a deflection effort would aim to change an object’s course without creating fragments that could still threaten Earth.
The model combines Sandia’s ALEGRA and SPARTA codes to calculate different parts of the problem, according to The Register. The combined approach is reported to run more than 1,600 times faster than earlier methods, allowing researchers to test more modeled scenarios.
Why shape matters
The simulations account for three-dimensional asteroid shapes rather than treating the bodies as spheres, a common simplification in earlier modeling, Moore told KRQE. Researchers can also vary the blast’s size, distance and target side, Newswise reported.
The modeling builds on earlier research into X-ray-based deflection. Lab experiments reported by Science News used X-rays to heat free-falling mock asteroids, producing vapor that pushed them away. Simulations based on those experiments suggested the method could deflect some asteroids up to about 4 kilometers wide.
NASA’s DART mission demonstrated that a spacecraft can be directed at a near-Earth object. Sandia’s calculations address a different proposed method: changing an asteroid’s motion with X-rays from a nuclear detonation. The simulations offer predictions about how shape and orientation may affect that approach, but do not establish how a real deflection mission would perform.
The wider tracking challenge
NASA’s graphic counted more than 1,400 known potentially hazardous asteroids as of early 2013. The designation reflects their size and orbits that pass close to Earth’s orbit; it does not mean they are expected to hit Earth. NASA says continued observation and tracking can refine their orbits and improve predictions of future close approaches and impact probabilities, according to NASA Science.
From test to response planning
NASA reported that its DART spacecraft struck Dimorphos in the Didymos system on Sept. 26, 2022, shortening Dimorphos’ orbit around Didymos by 32 minutes—a demonstrated kinetic impact, unlike Sandia’s simulated X-ray approach. The European Space Agency says its Hera mission will study the aftermath of that impact, providing follow-up data on a different asteroid system and deflection technique. The International Asteroid Warning Network, coordinated by NASA, is a worldwide collaboration of asteroid astronomers and modelers that supports international responses to near-Earth-object threats, according to IAWN. The United Nations Office for Outer Space Affairs says the Space Mission Planning Advisory Group lays out frameworks, timelines and options for response activities. These are coordination roles, not evidence that Sandia’s model is an approved mission.
