NASA has made public a summary of the biennial Planetary Defense Interagency Tabletop Exercise held in April 2024. The exercise was conducted to inform and assess the US’s ability to respond effectively to the threat of a potentially hazardous asteroid or comet. Multiple other agencies were involved, including the Federal Emergency Management Agency and the Department of State Office of Space Affairs.
Although there are no known significant asteroid impact threats for the foreseeable future, hypothetical exercises provide valuable insights by exploring the risks, response options, and opportunities for collaboration posed by varying scenarios, from minor regional damage with little warning to potential global catastrophes predicted years or even decades in the future.
“The uncertainties in these initial conditions for the exercise allowed participants to consider a particularly challenging set of circumstances,” said NASA’s Lindley Johnson. “A large asteroid impact is potentially the only natural disaster humanity has the technology to predict years in advance and take action to prevent.”
During the exercise, participants considered potential national and global responses to a hypothetical scenario in which a never-before-detected asteroid was identified that had, according to initial calculations, a 72% chance of hitting Earth in approximately 14 years. The preliminary observations described in the exercise were insufficient to precisely determine the asteroid’s size, composition, and long-term trajectory. To complicate the hypothetical scenario, essential follow-up observations would have to be delayed for at least seven months, a critical loss of time, as the asteroid passed behind the Sun as seen from Earth’s vantage point in space.
Conducting exercises allows government stakeholders to identify and resolve potential issues as part of preparation for any real-world situation. It was held at the Johns Hopkins Applied Physics Laboratory in Maryland and brought together nearly 100 representatives from across US government agencies and, for the first time, international collaborators on planetary defence.
This exercise was the first to use data from NASA’s DART (Double Asteroid Redirection Test) mission, the first in-space demonstration of a technology for defending Earth against potential asteroid impacts. The DART spacecraft, which impacted the asteroid moonlet Dimorphos on Sept. 26, 2022, confirmed that a kinetic impactor could change an asteroid’s trajectory. Applying this or any type of technology to an actual impact threat would require many years of advance planning.
To help ensure agencies will have the time needed to evaluate and respond to a potentially hazardous asteroid or comet, NASA continues the development of its Near-Earth Object Surveyor, an infrared space telescope specifically designed to expedite the discovery and characterisation of most of the potentially hazardous near-Earth objects many years before they could become an impact threat. The proposed launch date of NASA’s NEO Surveyor is June 2028.
NASA will publish a complete after-action report for the tabletop exercise later, including strengths and gaps identified from analysis of the response, other discussions during the exercise, and recommendations for improvement.
“These outcomes will help to shape future exercises and studies to ensure NASA and other government agencies continue improving planetary defence preparedness,” said Johnson.
NASA established the Planetary Defense Coordination Office in 2016 to manage the agency’s ongoing planetary defence efforts. Johns Hopkins APL managed the DART mission for NASA as a project of the agency’s Planetary Missions Program Office.
