The collision of the DART probe with the asteroid Dimorphos resulted in the ejection of more than five million kilos of material

The IEEC has participated in the first analyses of this NASA mission

DART has demonstrated great potential for active planetary defence against asteroid impact hazards

On 27 September 2022, NASA's DART (Double Asteroid Redirection Test) mission collided with its target, the asteroid Dimorphos, and changed its orbit. It was the first planetary defence test mission designed to change the course of an asteroid and its success was followed by intensive analysis of the collision, including study of the tonnes of rock that were displaced and hurled into space. The results of these analyses are published today in four papers in Nature, which involved teams from the Institute of Space Studies of Catalonia (IEEC — Institut d'Estudis Espacials de Catalunya) at the Institute of Space Sciences (ICE-CSIC), as well as from the Instituto de Astrofísica de Andalucía (IAA-CSIC).

The DART mission sought to demonstrate the usefulness of the kinetic impact method for deflecting potentially hazardous asteroids without using explosive charges. Its target was the Dimorphos satellite, about 160 metres in diameter, which orbits the asteroid Didymos (780 metres in diameter), forming a binary system. The impact of the spacecraft deflected the orbit of Dimorphos and shortened its translation period with respect to Didymos by more than half an hour, which was a success for the project.

Josep Maria Trigo, IEEC researcher at ICE-CSIC, has studied and interpreted the images of Dimorphos obtained by the Draco camera on board DART and also from the Italian probe LICIACube, as well as the effects produced in the environment of the binary system before and after the impact. The ICE-CSIC team's specialisation in the chondritic meteorites that make up these asteroids has made it possible to improve the interpretation of the processes occurring in them. The researcher has also contributed to the quantification of the impulse factor produced by the DART collision, the so-called beta factor, participating in three of the four articles published by Nature.

"Through these images we have seen the effects caused by the impact of DART, since for several weeks the measurements of the period of revolution of Dimorphos were hindered by the enormous amount of dust emitted from the crater left by DART. We cannot forget that Dimorphos is highly fractured by colossal impacts and appears to have a fragile rubble-pile structure," says Trigo.

Scientists have found that a probe like DART has great potential to be effective. "Humanity now has a plan in case it discovers an asteroid on a direct collision path with Earth. In fact, we could say that DART has ushered in a new era of active planetary defence against the danger of asteroid impact," explains Trigo.

The characterisation of the ejected material after the collision is another aspect that needed to be studied. Thus, from the moment of impact until several months later, the Hubble Space Telescope (HST) has been taking images of this material and characterising its evolution. Fernando Moreno, researcher at the IAA-CSIC, explains: “Although part of the material consists of particles ejected at high velocity, at several hundred metres per second, and which quickly disappears from the field of view of the cameras, we have been able to observe the low velocity component.”

This work presents a fundamentally morphological study of the evolution of this material, which has made it possible to determine the complex interaction between the asteroid system and the dust under the action of the radiation pressure produced by sunlight.

"As DART excavates the impact crater, the surface and subsurface structure of the asteroid plays a role. Large rocks are thrown but, to a large extent, we have seen that many have been weakened by space weathering on the asteroid's surface and, therefore, were preferentially shattered by the impact and immediately thrown into space in the opposite direction to the projectile as centimetre- to micrometre-sized particles, which are then subjected to the radiation pressure of the sunlight itself," says Trigo, co-author of the paper.

"This radiation pressure pushes micrometre-sized particles away to distances of several thousand kilometres in a couple of days, while the larger particles show spiral motions around the system and a complicated evolution over days. We see, for example, the appearance of a double tail, which could be related to the re-impact of a portion of the larger emitted particles or boulders on the surface of Didymos, or to the disintegration of those same boulders due to a high rotation speed or mutual collisions," says Moreno.

The DART mission's observations will soon produce more results. In addition, "we will soon gain a better understanding of the structure, composition and porosity of both asteroids thanks to the arrival of the European Space Agency (ESA) Hera mission to this binary system, which will allow us to delve even deeper into the dynamic origin and evolution of these bodies, representative of those that could threaten life on Earth," concludes Trigo.

Press release prepared in collaboration with the Communication offices of the CSIC, the Instituto de Astrofísica de Andalucía (IAA-CSIC) and the Instituto de Ciencias del Espacio (ICE-CSIC).

Main Image

Caption: The asteroid Dimorphos.
Credits: DART / NASA

Links

– DART
– IEEC
– ICE-CSIC
– IAA-CSIC

More information

This research is presented in several papers:

Cheng A., et al. «Momentum Transfer from the DART Mission Kinetic Impact on Asteroid Dimorphos», Nature.
Daly T., et al. «Successful Kinetic Impact into an Asteroid for Planetary Defense». Nature.
Li J.-Y., et al. «Ejecta from the DART-produced active asteroid Dimorphos». Nature.

The Institute of Space Studies of Catalonia (IEEC  — Institut d’Estudis Espacials de Catalunya) promotes and coordinates space research and technology development in Catalonia for the benefit of society. IEEC fosters collaborations both locally and worldwide and is an efficient agent of knowledge, innovation and technology transfer. As a result of 25 years of high-quality research, done in collaboration with major international organisations, IEEC ranks among the best international research centers, focusing on areas such as: astrophysics, cosmology, planetary science, and Earth Observation. IEEC’s engineering division develops instrumentation for ground- and space-based projects, and has extensive experience in working with private or public organisations from the aerospace and other innovation sectors.

IEEC is a private non-profit foundation, governed by a Board of Trustees composed of Generalitat de Catalunya and four other institutions that each have a research unit, which together constitute the core of IEEC R&D activity: the Universitat de Barcelona (UB) with the research unit ICCUB — Institute of Cosmos Sciences; the Universitat Autònoma de Barcelona (UAB) with the research unit CERES — Center of Space Studies and Research; the Universitat Politècnica de Catalunya · BarcelonaTech (UPC) with the research unit CTE — Research Group in Space Sciences and Technologies; the Spanish Research Council (CSIC) with the research unit ICE — Institute of Space Sciences. The IEEC is a CERCA (Centres de Recerca de Catalunya) center.

Contacts

IEEC Communication Office
Barcelona, Spain
E-mail: comunicacio@ieec.cat 

Lead Researcher at IEEC
Barcelona, Spain
Josep M. Trigo
Institute of Space Studies of Catalonia (IEEC)
Institute of Space Sciences (ICE-CSIC)
E-mail: trigo@ieec.cat