Asteroid aftermath: NASA’s DART impact captured by ESO telescope

22 Mar 2023

An artist's illustration of NASA's DART spacecraft colliding with the asteroid Dimorphos. Image: ESO/M. Kornmesser

Humanity’s first planetary defence test presented an opportunity for astronomers to learn more about the asteroid, by analysing the expelled material.

The aftermath of NASA’s Double Asteroid Redirection Test (DART) has been analysed by astronomers to learn more about the asteroid’s composition.

Last September, the DART spacecraft completed its 10-month journey when it successfully collided with the asteroid Dimorphos in humanity’s first planetary defence test.

The mission was an experiment to see if an asteroid’s path can be changed by crashing into it, using a technique known as kinetic impact. This effort was proven to be successful and marked humanity’s first time purposely changing the motion of a celestial object.

But the collision into Dimorphos also created an opportunity for astronomers to learn more about the asteroid by analysing the expelled material.

The collision’s aftermath was observed by the European Southern Observatory’s (ESO) Very Large Telescope. The first results of these observations have been published this week in two papers.

Brian Murphy, a PhD student at the University of Edinburgh and a co-author of one of the studies, said asteroids are some of the “most basic relics” of what larger objects within the solar system were created from.

By analysing the ejected material from the collision, it is hoped that astronomers can learn more about how the solar system was formed.

One research team followed the evolution of the cloud of debris for a month with the ESO telescope’s Multi Unit Spectroscopic Explorer. This team was led by Cyrielle Opitom, an astronomer at the University of Edinburgh.

This analysis found that the ejected cloud was bluer than the asteroid was before the impact, which suggests the cloud could be made of very fine particles.

Another team studied how the DART impact altered the surface of the asteroid. This team was led by Stefano Bagnulo, an astronomer at the Armagh Observatory and Planetarium. The results of this study suggest more pristine material could be lurking under the surface of the asteroid.

The analysis of the data is ongoing, but Opitom said the research took advantage of a unique opportunity, as it “cannot be repeated by any future facility.”

“This makes the data obtained with the [Very Large Telescope] around the time of impact extremely precious when it comes to better understanding the nature of asteroids,” Opitom said.

At the time of the DART impact, the James Webb Space Telescope and the Hubble Space Telescope took simultaneous observations of the collision to observe the results with various instruments.

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Leigh Mc Gowran is a journalist with Silicon Republic