Asteroids headed for a collision with the Earth, if found early enough, can be acted upon to prevent the potentially devastating consequences of an impact. One technique to divert an asteroid, called kinetic impact, uses a spacecraft to crash into the body at high speeds.This approach delivers the momentum of the spacecraft, while also providing an additional boost of momentum through the production of impact crater ejecta exceeding the asteroid’s escape velocity. Researchers at Lawrence Livermore National Laboratory (LLNL) have been studying the effectiveness of the kinetic-impactor strategy by carrying out 3D simulations of the process.In a new paper published in Icarus(link is external), LLNL planetary defense researchers find that asteroid deflection by kinetic impact is sensitive to a range of asteroid characteristics, including strength, porosity, rotation and shape. These and other asteroid properties may not be well constrained before an actual deflection mission is staged, leading to variability in the deflection outcome. By simulating a range of initial conditions for the target asteroids, researchers were able to quantify, for example, how greater target strength decreases the delivered momentum impulse and how, for an asteroid of constant size, added porosity can result in more effective deflections, despite the dampening of the shock waves produced during an impact