Asteroid Threat Assessment Project

Image of ground damage risk swath from a hypothetical asteroid scenario. — Hypothetical damage risk swath: Shows extent of regions potentially at risk to local ground damage, given ranges of potential damage sizes and locations (not representative of likelihood). *Lorien Wheeler, NASA/Ames*

The Asteroid Threat Assessment Project (ATAP) at NASA’s Ames Research Center leverages the center’s expertise in planetary science, atmospheric entry, supercomputing simulations, and risk assessment to evaluate the threat to Earth due to asteroid impacts.

The ATAP team supports NASA’s Planetary Defense Coordination Office and the National Near-Earth Object Preparedness Strategy and Action Plan, working with a multi-agency modeling working group to develop national threat assessment capabilities that will be employed if an actual asteroid impact threat is discovered.

To pursue this goal, the ATAP team develops state-of-the-art models across four key areas: impact risk assessment, impact hazard modeling, atmospheric entry, and asteroid property characterization.

Risk Assessment

The ATAP team uses their Probabilistic Asteroid Impact Risk (PAIR) model to estimate the severity and likelihood of damage that could result from potential asteroid impacts, including modeling of asteroid entry and breakup, blast waves, thermal radiation, tsunamis, and global climatic effects. PAIR utilizes fast running engineering models to sample over the range of possible entry parameters and potential asteroid physical properties.

Impact Hazard Modeling and Simulation

Utilizing a variety of high-performance computing codes (including NASA’s Cart3D, USM3D, and NERO; Lawrence Livermore Lab’s ALE3D; and the open source GeoClaw) the ATAP team runs high-fidelity physics-based simulations of potential hazards that could result from an asteroid impact, including blast waves, thermal radiation, and tsunamis. These high-fidelity models are used to simulate the hazards that could result from specific entry cases and to investigate how various scenario parameters affect the resulting hazard. The ATAP team leverages the insights gained from these high-fidelity hazard models to develop and verify fast-running engineering models of hazards for use in risk assessment.

Atmospheric Entry

Image from a simulation of an asteroid entering Earth's atmopshere — Simulation of a 120-meter asteroid entering the atmosphere at 20 kilometers per second (km/s) and impacting the ground, releasing the energy equivalent of about 100 megatons of TNT. After the impact occurs, the blast wave propagates over the region (colored by contours of local Mach number). The recoil up the entry corridor and blast from the ground impact are clearly visible. *Michael Aftosmis, Marian Nemec, NASA/Ames*

The ATAP team leverages Ames’ expertise in atmospheric entry to study the details of how an asteroid would potentially interact with Earth’s atmosphere. The team has adapted existing atmospheric entry computational tools to the asteroid entry scenario to investigate radiation emissions. In addition, they have utilized a variety of experimental techniques, including using the Ames ARCJet Complex to investigate how various meteorite and similar terrestrial rock materials respond to the extreme conditions that occur during atmospheric entry.

Asteroid Property Models

ATAP leverages NASA expertise in planetary science to model physical parameters of potential impactors, perform experimental measurements of relevant meteorite properties, and generate a database of light curves from the atmospheric entries of observed bright meteors, called bolides. The team combines statistical techniques with knowledge about the population of near-Earth asteroids to develop models representing the ranges and likelihoods of relevant asteroid properties, such as size, density, and porosity. These models are used in ATAP’s risk assessments and by collaborators who study planetary defense mitigation missions.

ATAP has significantly increased the available measurements for several key meteorite properties, including high-temperature thermal conductivity and acoustic velocities. The team has developed a method to identify bolide entries in data from the Geostationary Lightning Mapper on the Geostationary Operational Environmental Satellites (GOES) satellite network. The resulting data is hosted on the publicly accessible and regularly updated Bolides Detections from Geostationary Lightning Mapper website.

Planetary Defense Exercise and Scenario Support

ATAP combines its various areas of expertise to support numerous hypothetical asteroid impact exercises, including biannual international Planetary Defense Conference exercises, NASA/FEMA interagency planetary defense tabletop exercises, and international observing campaign exercises performed during the close approach of several real asteroids. These efforts are helping to make sure that all the key agencies and international organizations know how to work together to assess such a threat and develop the most effective mitigation strategies.

ATAP is supported by NASA’s Planetary Defense Coordination Office.