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Scientists Use Supercomputers to Predict Asteroid Damage on Earth

Video from a simulation of an airburst from an altitude of about 10 kilometers (km), generated by a meteoroid with an entry speed of 20 km/s and a diameter of about 60 meters. The energy release is equivalent to 10 megatons of TNT. The vertical extent of the domain is about 50 km and the horizontal extent is over 80 km. The first half of the movie shows propagation of the primary and secondary shockwaves with Mach contours; the second half shows convection and dissipation of the meteoroid wake with temperature contours. Michael Aftosmis, Marian Nemec, NASA/Ames

What would happen if a big meteor was speeding toward Earth? Since 2008, NASA has been leading the U.S. effort to provide warnings and reduce the potential hazards of asteroid impacts on Earth. Specifically, NASA's Planetary Defense Coordination Office has been chartered to "coordinate the detection, tracking, and characterization information of NEOs [near-Earth objects] from all organizations, domestic and international, within the astronomical observation community."

Scientists working on the Asteroid Threat Assessment Project (ATAP) at NASA's Ames Research Center in Silicon Valley are using specialized software and supercomputers to calculate risks and assess possible damage that might occur when asteroids enter the planet's atmosphere.

The ATAP team's Probabilistic Asteroid Impact Risk (PAIR) model captures the key physics involved in an asteroid's entry and airburst blast, a phenomenon that occurs when an incoming asteroid or comet explodes in the Earth's atmosphere. PAIR is able to efficiently model millions of hypothetical impact cases to provide estimates of damage caused by blast waves, thermal radiation, tsunamis from ocean impacts, and large-scale global effects. The team also uses NASA's computational fluid dynamics software called CART3D—originally developed to model heat shields for aircraft and spacecraft—to run high-fidelity simulations of hypothetical impact blasts on the Pleiades supercomputer. Using these simulations, the team can accurately predict the shock wave arrival times and damage from the heat and pressure waves generated by such events.

This movie shows a simulation of an airburst at an altitude of about 10 kilometers, produce by a small meteoroid 60 meters in diameter entering the atmosphere at 20 kilometers per second—about 44,740 miles per hour! The energy released is equivalent to 10 megatons of TNT.

Luckily for us, such large asteroid impacts are rare, but that means recorded data is also limited. To fill in the gaps in observational data, the ATAP scientists are running large-scale simulations based on data from the relatively small (20-meter) asteroid that airburst over Chelyabinsk, Russia in 2013. The results are then used to validate and refine the PAIR model's damage and risk predictions. Simulation results for the Chelyabinsk airburst closely matched documented ground pressures and shock arrival times at specific locations covering 15,000 square miles of the surrounding countryside. These highly accurate simulations are fed back into the PAIR model to improve damage predictions for future impacts.

In February of this year, taking into account the knowledge gained from Chelyabinsk simulations, the team presented new work at the Ames-hosted Tunguska Workshop to re-examine the 1908 Tunguska asteroid event in Siberia. Also, in a new NASA in Silicon Valley podcast, ATAP team members Donovan Mathias and Eric Stern talk about their paths leading to asteroid research.

—Jill Dunbar, NASA/Ames Research Center