Sandia model: asteroid orientation changes X-ray deflection velocity up to 5× in simulation
Simulations of Bennu, Itokawa and Golevka show that the side hit by an X-ray pulse sets the deflection velocity. The method is over 1,600 times faster than the old one.
Physicists at Sandia National Laboratories, led by Nathan Moore, have published in Icarus a computational method for predicting how a kilometer-scale asteroid of arbitrary shape responds to a stand-off X-ray pulse. The article appeared on 24 October 2026. In simulations of three real bodies, the orientation of the asteroid at the moment of intercept changed the deflection velocity by up to a factor of five doi.org
Icarusdoi.orgOpen source ↗.
Most earlier models treated asteroids as spheres, because this simplifies the calculation. According to Moore, the new approach keeps both realistic topography and detailed physics doi.org
Icarusdoi.orgOpen source ↗.
Two-stage calculation
The method has two steps. First, one-dimensional radiation-hydrodynamics calculations predict gas ejection, accounting for radiation scattering, heating, phase change, shock hydrodynamics and thermal re-emission in a coupled manner doi.org
Icarusdoi.orgOpen source ↗. Then Direct Simulation Monte Carlo (DSMC) gas dynamics, which scales better in three dimensions, gives the vapor evolution and surface pressure over the whole body
doi.org
Icarusdoi.orgOpen source ↗.
According to the release, the team combined two Sandia codes: ALEGRA, normally used for fast high-energy experiments, and SPARTA, a DSMC code. The asteroid model is built from high-resolution 3D imagery from spacecraft flybys. Moore said the new algorithm is over 1,600 times faster than the old models.
Orientation matters
The authors computed deflection of asteroids (101955) Bennu, (25143) Itokawa and (6489) Golevka for near-field and far-field irradiation. Compared with the minimum response of each body, orientation at intercept raised the deflection velocity by up to nearly 2× for Bennu, 4× for Itokawa and 5× for Golevka doi.org
Icarusdoi.orgOpen source ↗.
In one case described in the release, the deflection velocity was 3.9 mm/s from one angle and 0.8 mm/s from another. For a different asteroid, the change in rotational speed after deflection varied by a factor of 17. The paper also discusses changes in rotational velocity doi.org
Icarusdoi.orgOpen source ↗.
The authors also mapped the pressure fields onto a loosely compacted, Itokawa-like boulder assembly. Solid ejecta from shock-wave fracturing and rubble ejecta proved highly asymmetric doi.org
Icarusdoi.orgOpen source ↗.
Limitations
The model currently considers only the breakup of rocks on the surface. Moore said the breakup of the entire asteroid cannot yet be predicted accurately. The simulation also needs fairly accurate shape data from all sides of the asteroid, which may not be available in a real case.
