Dimorphos From Wikipedia, the free encyclopedia Jump to navigation Jump to search Dimorphos Radar images of Didymos and its satellite Dimorphos by the Arecibo Observatory in 2003 Discovery[1] Discovered by Petr Pravec et al.[a] Discovery date 20 November 2003 Designations Designation Didymos I Pronunciation /daɪˈmɔːrfəs/ Named after Greek word for "having two forms"[2] Alternative names S/2003 (65803) 1 Orbital characteristics[1] Semi-major axis 1.19±0.03 km Eccentricity < 0.05 Orbital period 0.4971±0.0004 d or 11.93±0.01 hr Satellite of 65803 Didymos Physical characteristics[1] Mean diameter 0.170±0.030 km or 170±30 m Absolute magnitude (H) 21.3±0.2 (difference from primary)[1] Dimorphos is a small asteroid satellite that was discovered in 2003. It is the minor-planet moon of a synchronous binary system with 65803 Didymos as the primary asteroid. After being provisionally designated as S/2003 (65803) 1 with informal nicknames such as "Didymos B" and "Didymoon", the Working Group Small Body Nomenclature (WGSBN) of the International Astronomical Union gave the satellite its official name on 23 June 2020.[3] At a diameter of 170 metres (560 ft), it is one of the smallest astronomical objects that has been given a permanent name.[2] Dimorphos is the target of NASA's Double Asteroid Redirection Test (DART), a mission spacecraft of which was launched on 24 November 2021 with a planned impact between 26 September and 1 October 2022. The DART mission is a test of planetary defence against asteroids.[4] A flyby mini-satellite named LICIACube, provided by the Italian Space Agency, will photograph the collision. The European Space Agency's Hera mission will observe the asteroid after the impact.[5] Contents 1 Discovery 2 Naming 3 Characteristics 4 Exploration 5 Notes 6 References Discovery[edit] The primary asteroid was discovered in 1996 by Joe Montani of the Spacewatch Project at the University of Arizona. The name Didymos was officially approved in 2004.[1] Petr Pravec of the Ondřejov Observatory in the Czech Republic found in 2003 that the asteroid had a satellite orbiting it. With his collaborators, he confirmed from the Arecibo radar delay-Doppler images that Didymos is a binary system.[6] Naming[edit] The name is derived from a Greek word Dimorphos, meaning "having two forms".[7] The name was suggested by planetary scientist Kleomenis Tsiganis at the Aristotle University of Thessaloniki. The justification for the new name reads: "As the target of the DART and Hera space missions, it will become the first celestial body in cosmic history whose form was substantially changed as a result of human intervention (the DART impact)". Tsiganis further explained that the name "has been chosen in anticipation of its changes. It will be known to us in two very different forms, the one seen by DART before the impact, and the other seen by Hera a few years later".[2] Prior to the IAU naming, the nickname "Didymoon" was used in official communications.[8] Characteristics[edit] Shape model of Didymos and its satellite Dimorphos, based on photometric lightcurve and radar data The primary body of binary system, Didymos, orbits the Sun at a distance of 1.0–2.3 AU once every 2 years and 1 month (770 days). The pathway of the orbit has an eccentricity of 0.38 and an inclination of 3° with respect to the ecliptic. It was known to be closest to Earth in November 2003 with a distance of 7.18 million km. It is expected to come around that near after 120 years.[9] Dimorphos moves mostly in a circular, equatorial orbit around Didymos, with an orbital period of 11.9 hours. Its orbit is retrograde relative to the ecliptic plane since Didymos's rotation is retrograde.[10] It measures approximately 160 metres (520 ft) in diameter, compared to Didymos which is 780 metres (2,560 ft) across.[11] Exploration[edit] On 24 November 2021, NASA launched the Double Asteroid Redirection Test (DART) spacecraft on a SpaceX Falcon 9 rocket from Space Launch Complex 4 East at Vandenberg Space Force Base in California, US.[12] DART is the first experiment for defending Earth from hazardous asteroids, and the spacecraft will try to deflect Dimorphos slightly from its position.[13] The spacecraft is expected to crash into Dimorphos at a speed of around 15,000 mph (6.6 km/s)[13] between 26 September and 1 October 2022.[14] The collision is expected to bring Dimorphos and Didymos closer to each other.[15][16] Dimorphos will then circles Didymos at least 73 seconds faster than before.[13] so that its orbit is shortened by 10 to 20 minutes.[15] The DART spacecraft is accompanied by LICIACube, a flyby Cubesat of the Italian Space Agency (ASI) 6-Unit, that will be released 10 days before impact to record the collision.[12] Then the European Space Agency will send its Hera spacecraft to Dimorphos in 2024 to study the impact crater and the new orbit of the binary system.[16] Notes[edit] ^ Astronomers involved in the discovery include P. Pravec, L. A. M. Benner, M. C. Nolan, P. Kusnirak, D. Pray, J. D. Giorgini, R. F. Jurgens, S. J. Ostro, J.-L. Margot, C. Magri, A. Grauer, and S. Larson using lightcurve observations from Ondrejov Observatory, Czech Republic; Jet Propulsion Laboratory; National Astronomy and Ionosphere Center; Ondrejov Observatory, Czech Republic; Greene, Rhode Island, USA; University of California, Los Angeles, California, USA; University of Maine at Farmington, Maine, USA; University of Arkansas at Little Rock, Arkansas, USA; University of Arizona, Arizona, USA.[1] References[edit] ^ a b c d e f "(65803) Didymos". www.johnstonsarchive.net. Retrieved 2021-11-11. ^ a b c International Astronomical Union (23 June 2020). "IAU Approves Name of Target of First NASA and ESA Planetary Defence Missions". www.iau.org. Retrieved 2020-07-01. ^ Temming, Maria (29 June 2020). "An asteroid's moon got a name so NASA can bump it off its course". ScienceNews. Retrieved 1 July 2020. ^ Potter, Sean (2021-11-23). "NASA, SpaceX Launch DART: First Test Mission to Defend Planet Earth". NASA. Retrieved 2021-11-25. ^ Witze, Alexandra (2021-11-19). "NASA spacecraft will slam into asteroid in first planetary-defence test". Nature. doi:10.1038/d41586-021-03471-w. ^ Pravec, P.; Benner, L. a. M.; Nolan, M. C.; Kusnirak, P.; Pray, D.; Giorgini, J. D.; Jurgens, R. F.; Ostro, S. J.; Margot, J.-L.; Magri, C.; Grauer, A. (2003). "(65803) 1996 GT". IAU Circular. 8244: 2. Bibcode:2003IAUC.8244....2P. ^ "MPEC 2020-M83 :". minorplanetcenter.net. Retrieved 2020-07-01. ^ "Target: Didymoon". www.esa.int. 2015-03-31. Retrieved 2021-11-24. ^ "JPL Small-Body Database Browser". ssd.jpl.nasa.gov. Retrieved 2020-07-01. ^ Scheirich, P.; Pravec, P.; Jacobson, S.A.; Ďurech, J.; Kušnirák, P.; Hornoch, K.; Mottola, S.; Mommert, M.; Hellmich, S.; Pray, D.; Polishook, D.; Krugly, Yu.N.; Inasaridze, R.Ya.; Kvaratskhelia, O.I.; Ayvazian, V.; Slyusarev, I.; Pittichová, J.; Jehin, E.; Manfroid, J.; Gillon, M.; Galád, A.; Pollock, J.; Licandro, J.; Alí-Lagoa, V.; Brinsfield, J.; Molotov, I.E. (2015). "The binary near-Earth Asteroid (175706) 1996 FG3 — an observational constraint on its orbital evolution". Icarus. 245: 56–63. arXiv:1406.4677. Bibcode:2015Icar..245...56S. doi:10.1016/j.icarus.2014.09.023. ^ "(65803) Didymos". www.johnstonsarchive.net. Retrieved 2020-07-01. ^ a b Greshko, Michael (2021-11-23). "This NASA spacecraft will smash into an asteroid—to practice saving Earth". National Geographic. Retrieved 2021-11-25. ^ a b c Rincon, Paul (2021-11-24). "Nasa Dart asteroid spacecraft: Mission to smash into Dimorphos space rock launches". BBC News. Retrieved 2021-11-25. ^ Potter, Sean (2021-11-23). "NASA, SpaceX Launch DART: First Test Mission to Defend Planet Earth". NASA. Retrieved 2021-11-25. ^ a b Temming, Maria (29 June 2020). "An asteroid's moon got a name so NASA can bump it off its course". ScienceNews. Retrieved 1 July 2020. ^ a b Crane, Leah (2021-11-23). "NASA's DART mission will try to deflect an asteroid by flying into it". New Scientist. Retrieved 2021-11-25. show vte 2022 in space show vte Natural satellites of the Solar System Categories: Asteroid satellitesNamed minor planetsRadar-imaged asteroidsAstronomical objects discovered in 2003 Not logged in Talk Contributions Create account Log in Article Talk Read Edit View history Search Main page Contents Current events Random article About Wikipedia Contact us Donate Contribute Help Learn to edit Community portal Recent changes Upload file Tools What links here Related changes Special pages Permanent link Page information Cite this page Wikidata item Print/export Download as PDF Printable version Languages العربية Ελληνικά Français Edit links This page was last edited on 25 November 2021, at 09:51 (UTC). Text is available under the Creative Commons Attribution-ShareAlike License; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. 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