Some active asteroids have been proposed to be formed as a result of impact events1. Because active asteroids are generally discovered by chance only after their tails have fully formed, the process of how impact ejecta evolve into a tail has, to our knowledge, not been directly observed. The Double Asteroid Redirection Test (DART) mission of NASA2, in addition to having successfully changed the orbital period of Dimorphos3, demonstrated the activation process of an asteroid resulting from an impact under precisely known conditions. Here we report the observations of the DART impact ejecta with the Hubble Space Telescope from impact time T + 15 min to T + 18.5 days at spatial resolutions of around 2.1 km per pixel. Our observations reveal the complex evolution of the ejecta, which are first dominated by the gravitational interaction between the Didymos binary system and the ejected dust and subsequently by solar radiation pressure. The lowest-speed ejecta dispersed through a sustained tail that had a consistent morphology with previously observed asteroid tails thought to be produced by an impact4,5. The evolution of the ejecta after the controlled impact experiment of DART thus provides a framework for understanding the fundamental mechanisms that act on asteroids disrupted by a natural impact.
|Early online date||01 Mar 2023|
|Publication status||Published - 20 Apr 2023|
Bibliographical noteFunding Information:
This work was supported by the DART mission, NASA contract no. 80MSFC20D0004 and by the Italian Space Agency (ASI) through the LICIACube project (ASI-INAF agreement AC no. 2019-31-HH.0). Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the NASA. J.-Y.L. acknowledges the support provided by NASA through grant HST-GO-16674 from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, under NASA contract NAS 5-26555. L.K. acknowledges support from the NASA DART Participating Scientist Program, Grant no. 80NSSC21K1131. R.L., D.A.G. and T.J.S. acknowledge funding from the NASA/GSFC Internal Scientist Funding Model (ISFM) Exospheres, Ionospheres, Magnetospheres Modeling (EIMM) team, the NASA Solar System Exploration Research Virtual Institute (SSERVI) and NASA award no. 80GSFC21M0002. R.M. acknowledges support from a NASA Space Technology Graduate Research Opportunities (NSTGRO) Award (contract no. 80NSSC22K1173). P.M. acknowledges funding support from the Horizon 2020 research and innovation programme of the European Union under grant agreement no. 870377 (project NEO-MAPP), the CNRS through the MITI interdisciplinary programmes, CNES and ESA. F.F. acknowledges funding from the Swiss National Science Foundation (SNSF) Ambizione grant no. 193346. J.O. has been funded by grant no. PID2021-125883NB-C22 by the Spanish Ministry of Science and Innovation/State Agency of Research MCIN/AEI/10.13039/501100011033 and by the European Regional Development Fund “A way of making Europe”. G.T. acknowledge financial support from project FCE-1-2019-1-156451 of the Agencia Nacional de Investigación e Innovación ANII (Uruguay). T. Kohout is supported by the Academy of Finland project 335595 and by institutional support RVO 67985831 from the Institute of Geology of the Czech Academy of Sciences. F.M. acknowledges financial support from grants CEX2021-001131-S funded by MCIN/AEI/10.13039/501100011033 and PID2021-123370OB-I00. Research by M.G. is supported, in part, by the Academy of Finland grant 345115. J.M.T.-R. acknowledges financial support from the project PID2021-128062NB-I00 funded by Spanish MCIN/AEI/10.13039/501100011033. We thank J. DePasquale (STScI) for generating the animation included in Supplementary Video .
© 2023, The Author(s).
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