WASHINGTON — A recent planetary defense exercise highlighted a different set of challenges governments would face about a threatening asteroid in a scenario where the impact is many years in the future.

NASA released June 20 a “quick look” report about the fifth in a series of tabletop exercises involving NASA and other government agencies, as well as international participants, regarding a hypothetical asteroid impact threat. The two-day exercise took place in early April at the Johns Hopkins University Applied Physics Lab (APL).

The previous such exercise, held in 2022, focused on the response to a short-term asteroid impact threat, which in that case involved a small asteroid that in the scenario ultimately hit North Carolina six months after discovery. That was intended to test how federal, state and local officials would respond, said Leviticus “L.A.” Lewis, a detailee from the Federal Emergency Management Agency (FEMA) to NASA’s Planetary Defense Coordination Office, at a June 20 briefing.

The April exercise instead focused on a long-term hypothetical scenario: the discovery of a near Earth object (NEO) that had a 72% chance of hitting Earth in 2038. In this exercise, participants had to grapple with uncertainties about its trajectory, with potential impact locations on a path that extended from Mexico and the United States to southern Europe and the Middle East, as well as the object’s size.

The exercise examined the initial response to such a discovery. “It’s the most likely scenario we would face if we’re successful in doing our search for the NEO population,” said Lindley Johnson, NASA’s planetary defense officer emeritus, at the briefing. “We will know years, even decades, in advance of a potential impact threat, and therefore have the necessary time to prepare for it.”

That long time frame, coupled with uncertainties, posed problems in the exercise. Participants developed three options for better understanding the impact threat. One involved getting more groundbased observations of the asteroid, which required waiting seven months until the asteroid was back in view from the Earth. Two others involved developing spacecraft missions, one a flyby spacecraft with an estimated cost of $200 million to $400 million, and the other a spacecraft to rendezvous with the asteroid at a cost of $800 million to $1 billion, to better understand the asteroid and its risk of impact.

Senior leaders participating in the exercise favored either of the spacecraft options, but argued the challenge would be obtaining funding for them. Political leaders, they noted, would want a better understanding of the asteroid risk before agreeing to fund missions that were intended to characterize that risk.

“Providing the right information and the right characterization of the situation for the decision to go do something — or not, as the prudent case may be — is one of the things we always worry about,” Johnson said. That means even a 14-year warning time can feel compressed.

“Examining how long it takes to pull a mission together, the flight time it takes to get to the asteroid and the launch windows that are available to get to the asteroid, that eats up a decade of time pretty fast, so that is certainly a concern looking at it from a technological standpoint,” he said.

Agencies like FEMA responsible for responding to disasters face a different problem from that long lead time. “Emergency managers and disaster responders are working every day. There’s always something happening,” Lewis said. “Figuring out where to put your resources to start working on this specific problem while still working on tornadoes, hurricanes, et cetera, is going to be a particular challenge.”

This tabletop exercise included for the first time international participants, with representatives from several space agencies as well as the United Nations Office for Outer Space Affairs. “In this exercise, we wanted to examine the processes by which we would come together, both interagency and internationally, to decide what is the right course of action,” Johnson said.

Lewis, though, noted that one issue was how to coordinate an international asteroid impact disaster response. “If we have a lot of time, maybe the U.N. is the right place, but it may not necessarily be under the Office for Outer Space Affairs.”

The exercise also demonstrated the importance of clear and accurate communications. “What is it that people would want to know, when would they want to know it, how to communicate it in an effective way,” said Terik Daly, planetary defense section supervisor at APL.

Johnson, who said he is “phasing into retirement” from NASA, noted more tabletop exercises are planned. “We’ll take a look at the outcomes and key gaps identified in this exercise and then we’ll try to craft the next exercise in such a way that forces us to address some of those outstanding issues and gaps,” he said.

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...