NASA Prepares Planetary Defense Exercise for Tunguska-Scale Asteroid Impact
Scientists developing risk models and simulations to address fundamental uncertainties about how asteroids behave during atmospheric entry and impact.
What happened
NASA's Asteroid Threat Assessment Project, led by Lorien Wheeler at Ames Research Center, is using probabilistic modeling and computer simulations to evaluate asteroid impact risks. The agency's Probabilistic Asteroid Impact Risk (PAIR) model assesses the range and likelihood of damage from potential impacts. A planetary defense exercise currently under development for the 2027 Planetary Defense Conference is based on a hypothetical Tunguska-sized object impact scenario.
Context
Planetary defense efforts face significant obstacles in predicting impact consequences. Critical variables remain uncertain: asteroid size, composition, structure, density, and impact location all influence whether an object will airburst in the atmosphere or strike the ground, and how much energy will be released. Even with historical data from the 1908 Tunguska airburst, scientists cannot fully predict fragmentation behavior during atmospheric entry, the height and force of an airburst, or the distribution of damage across blast waves, heat, cratering, and potential tsunamis. These modeling efforts and assessment methods inform mitigation missions and emergency response planning, making improved risk evaluation essential for planetary protection.