NASA’s Double Asteroid Redirection Test (DART) mission is the world’s first full-scale test of planetary defenses once morest possible asteroid impacts on Earth. Researchers from the University of Bern and the National Center of Competence in Research (NCCR) PlanetS are now showing that the impact of the DART spacecraft on its target might make the asteroid almost unrecognizable instead of leaving behind a relatively small crater. A media release from the University of Bern.
Source: University of Bern June 29, 2022.
June 29, 2022 – 66 million years ago, a giant asteroid impact on Earth likely caused the dinosaur extinction. No known asteroid is currently an immediate threat. However, should a large asteroid be discovered on a collision course with Earth, it may need to be deflected from its trajectory to avoid catastrophic consequences.
Last November, the DART spacecraft of the US space agency NASA launched as the first experiment of its magnitude for such a maneuver: Your task is to collide with an asteroid and deflect it from its orbit. In this way, valuable information for the development of such a planetary defense technology should be gained.
In a new study published in the Planetary Science Journal, researchers from the University of Bern and the National Center of Competence in Research (NCCR) PlanetS simulated this impact using a new method. Their results suggest that it might deform its target much more than previously thought.
Rubble instead of solid rock
“Contrary to what one imagines an asteroid to be, direct studies of space missions such as the Japanese Space Agency’s Hayabusa2 probe show JAXAthat asteroids can have a very loose internal structure – similar to a pile of rubble – which is held together by gravitational interactions and small cohesive forces,” says lead author Sabina Raducan from the Physics Institute and the National Center of Competence in Research PlanetS at the University of Bern.
However, previous simulations of the DART mission’s impact mostly assumed a much firmer interior of the target asteroid Dimorphos. “This might drastically change the outcome of the DART-Dimorphos clash planned for next September,” Raducan said. Instead of leaving a relatively small crater on the 160-metre-wide asteroid, DART’s impact, traveling at around 24,000 km/h, might completely deform Dimorphos. The asteroid might also be deflected much more sharply and eject larger amounts of material than previous estimates predicted.
An award-winning new approach
“One of the reasons why this scenario of a loose internal structure has not been thoroughly investigated is that the necessary methods were not available,” says Raducan. “Such impact conditions cannot be simulated in laboratory experiments, and the relatively long and complex process of crater formation following such an impact – in the case of DART a matter of hours – has made it impossible to realistically simulate these impact processes until now,” says the researcher.
“With our novel modeling approach, which takes into account the propagation of the shock waves, the compression and the subsequent flow of material, we were able for the first time to model the entire cratering process that occurs when small asteroids such as Dimorphos impact,” reports Raducan. For this achievement she was recognized by the European Space Agency at a workshop on the DART follow-up mission HERA ESA and awarded by the Mayor of Nice.
An extension of the expectation horizon is required
In 2024 the ESA send a space probe to Dimorphos as part of the HERA space mission. The aim is to visually examine the consequences of the impact of the DART probe. “In order to get the most out of the HERA mission, we need to have a good understanding of the possible consequences of the DART impact,” says study co-author Martin Jutzi from the Physics Institute and the National Center of Competence in Research PlanetS at the University of Bern. “Our work on the impact simulations adds an important potential scenario that compels us to expand our expectations in this regard. This is not only relevant in the context of planetary defense, but also adds an important piece of the puzzle to our understanding of asteroids in general,” concludes Jutzi.
publication
Sabina D. Raducan and Martin Jutzi: Global-scale Reshaping and Resurfacing of Asteroids by Small- scale Impacts, with Applications to the DART and Hera Missions, The Planetary Science Journal, June 2022, DOI: 10.3847/PSJ/ac67a7
https://iopscience.iop.org/article/10.3847/PSJ/ac67a7
