PLANETARY SECURITYMethod for Decoding Asteroid Interiors Could Help Aim Asteroid-Deflecting Missions
Knowing how the density is distributed inside an asteroid could help scientists plan the most effective defense. For instance, if an asteroid were made of relatively light and uniform matter, a DART-like spacecraft could be aimed differently than if it were deflecting an asteroid with a denser, less balanced interior. Astronomers have found a way to determine an asteroid’s interior structure based on how its spin changes during a close encounter with Earth.
NASA hit a bullseye in late September with DART, the Double Asteroid Redirection Test, which flew a spacecraft straight at the heart of a nearby asteroid. The one-way kamikaze mission smashed into the stadium-sized space rock and successfully reset the asteroid’s orbit. DART was the first test of a planetary defense strategy, demonstrating that scientists could potentially deflect an asteroid headed for Earth.
Now MIT researchers have a tool that may improve the aim of future asteroid-targeting missions. The team has developed a method to map an asteroid’s interior structure, or density distribution, based on how the asteroid’s spin changes as it makes a close encounter with more massive objects like the Earth.
Knowing how the density is distributed inside an asteroid could help scientists plan the most effective defense. For instance, if an asteroid were made of relatively light and uniform matter, a DART-like spacecraft could be aimed differently than if it were deflecting an asteroid with a denser, less balanced interior.
“If you know the density distribution of the asteroid, you could hit it at just the right spot so it actually moves away,” says Jack Dinsmore ’22, who developed the new asteroid-mapping technique as an MIT undergraduate majoring in physics.
The team is eager to apply the method to Apophis, a near-Earth asteroid that is estimated to pose a significant hazard if it were to make impact. Scientists have ruled out the likelihood of a collision during Apophis’ next flybys for at least a century. Beyond that, their forecasts grow fuzzy.
“Apophis will miss Earth in 2029, and scientists have cleared it for its next few encounters, but we can’t clear it forever,” says Dinsmore, who is now a graduate student at Stanford University. “So, it’s good to understand the nature of this particular asteroid, because if we ever need to redirect it, it’s important to understand what it’s made of.”
Dinsmore and Julien de Wit, assistant professor in MIT’s Department of Earth, Atmospheric and Planetary Sciences (EAPS), detail their new method in a study appearing today in the Monthly Notices of the Royal Astronomical Society.
