View source for 65803 Didymos

{{Short description|Near-Earth asteroid}}
{{Other uses|Didymos (disambiguation){{!}}Didymos}}
{{Use British English|date=June 2020}}
{{Use dmy dates|date=October 2019}}
{{Infobox planet
 | minorplanet     = yes
 | name            = 65803 Didymos
 | background      = #FFC2E0
 | image           = Didymos-Dimorphos true orientation.png
 | image_scale      =
 | caption         = Didymos (bottom left) and [[Dimorphos]] (top right) photographed by the [[Double Asteroid Redirection Test|DART]] space probe
 | discovery_ref   = &thinsp;<ref name="jpldata"/>
 | discovered      = 11 April 1996
 | discoverer      = [[Spacewatch]]
 | discovery_site  = [[Kitt Peak National Observatory]]
 | mpc_name        = (65803) Didymos
 | alt_names       = 1996 GT
 | pronounced      = {{IPAc-en|ˈ|d|ɪ|d|ᵻ|m|ɒ|s}}<ref>{{OED|didymous}}</ref>
 | named_after     = Greek word for "[[Twin]]"<ref name="springer"/>
 | mp_category     = [[Near-Earth object|NEO]]{{·}}[[Potentially hazardous object|PHA]]<br />[[Apollo asteroid|Apollo]] (2022)&thinsp;<ref name="jpldata"/>{{efn|name=Apollo}}
 | orbit_ref       = &thinsp;<ref name="jpldata"/>
 | epoch           = 21 January 2022 ([[Julian day|JD]] 2459600.5)
 | uncertainty     = 0
 | observation_arc = 24.82 years (9,066 days)
 | aphelion        = 2.2753 [[Astronomical unit|AU]]
 | perihelion      = 1.0131 AU
 | semimajor       = 1.6442 AU
 | eccentricity    = 0.38385
 | period          = 2.11 [[Julian year (astronomy)|yr]] (770 days)
 | mean_anomaly    = 232.01
 | mean_motion     = {{Deg2DMS|0.4673|sup=ms}} / day
 | inclination     = 3.4079°
 | asc_node        = 73.196°
 | arg_peri        = 319.32°
 | moid            = {{convert|0.0403|AU|LD|abbr=on|sigfig=3|lk=out}}
 | mars_moid       = {{convert|0.02|AU|LD|abbr=on}}<ref name="MPC-Didymos"/>
 | satellites      = 1 ([[Dimorphos]])
 | physical_ref    = <ref name="Cheng2023"/>
 | dimensions      = {{val|851|x|849|x|620}}&nbsp;m<br/>(± {{val|15|x|15|x|15}}&nbsp;m)
 | mean_diameter   = {{val|765|15|u=m}}{{efn|name=diameter|Volume-equivalent spherical diameter is calculated from an ellipsoid's volume given Didymos's dimensions of {{val|851|x|849|x|620}}&nbsp;m,<ref name="Cheng2023"/>{{rp|pages=28–29}} and then solving for radius with <math>r = \sqrt[3]{3 V \over 4 \pi }</math>.}}
 | surface_area    = 
 | volume          = 
 | mass            = {{val|5.4|0.4|e=11|u=kg}} (system)<ref name="Naidu2020"/><br/>{{val|5.2|e=11|u=kg|p=≈&thinsp;}} (primary)<ref name="Nakano2022"/>
 | density         = {{val|2.40|0.30|u=g/cm3}}<ref name="Cheng2023"/>
 | rotation        = {{val|2.2600|0.0001}}<ref name="Naidu2020"/><br/>{{val|2.2593|0.0002|ul=h}}<ref name="Pravec-2006"/>
 | pole_ecliptic_lon = {{val|310|20|u=°}}
 | pole_ecliptic_lat = {{val|-84|20|u=°}}
 | axial_tilt      = {{val|174|20|u=°}}{{efn|name=pole|Naidu et al. (2020) give the Didymos's north pole direction in terms of [[ecliptic coordinates]], where ''λ'' is ecliptic longitude and ''β'' is ecliptic latitude.<ref name="Naidu2020"/>{{rp|page=12}} ''β'' is the angular offset from the ecliptic plane whereas inclination ''i'' with respect to the ecliptic is the angular offset from the ecliptic north pole at ''β'' {{=}} +90°; ''i'' with respect to the ecliptic would be the [[Angle#Combining angle pairs|complement]] of ''β''.<ref name="coordstransform" /> Therefore, given ''β'' {{=}} –84°, ''i'' {{=}} 90° – (–84°) {{=}} 174° from the ecliptic.}}
 | albedo          = {{val|0.15|0.04}}
 | spectral_type   = [[S-type asteroid|S]]<ref name="Naidu2020"/><ref name="Scheirich2022"/>{{·}}[[SMASS classification|SMASS]] = [[X-type asteroid|X]][[K-type asteroid|k]]<ref name="jpldata"/>{{·}}[[X-type asteroid|X]]<ref name="lcdb"/>
 | abs_magnitude   = 18.0<ref name="jpldata"/>{{·}}18.16<ref name="lcdb"/><ref name="Pravec-2006"/><ref name="Kitazato-2004"/><br />{{val|18.16|0.03}}<ref name="Pravec-2012b"/>
}}
'''65803 Didymos''' ([[Minor planet provisional designation|provisional designation]] '''{{mp|1996 GT}}''') is a sub-[[kilometer]] [[asteroid]] and [[Binary asteroid|binary system]] that is classified as a [[potentially hazardous asteroid]] and [[near-Earth object]] of the [[Apollo asteroid|Apollo]] group.{{efn|name=Apollo}} The asteroid was discovered in 1996 by the [[Spacewatch]] survey at [[Kitt Peak National Observatory|Kitt Peak]], and its small 160-meter [[minor-planet moon]], named [[Dimorphos]], was discovered in 2003. Due to its binary nature, the asteroid was then named ''Didymos'', the [[Greek language|Greek]] word for 'twin'.

Didymos's moon, [[Dimorphos]], was the target of the [[Double Asteroid Redirection Test|DART]] mission to test the viability of [[asteroid impact avoidance]] by collision with a spacecraft, while the impact was witnessed by [[LICIACube]], a flyby [[CubeSat]] component of the mission.

== Discovery ==
[[File:Didymos-Arecibo-radar-images.png|thumb|left|Radar images of Didymos and its satellite [[Dimorphos]], taken by the [[Arecibo Observatory]] in 2003]]
Didymos was discovered on 11 April 1996 by the [[University of Arizona]] [[Steward Observatory]]'s, and [[Lunar and Planetary Laboratory]]'s, [[Spacewatch]] survey using its 0.9-meter telescope at [[Kitt Peak National Observatory]] in Arizona, United States. The binary nature of the asteroid was discovered by others; suspicions of binarity first arose in [[Goldstone Deep Space Communications Complex|Goldstone]] delay-[[Doppler radar|Doppler]] echoes, and these were confirmed with an optical [[lightcurve]] analysis, along with [[Arecibo Observatory|Arecibo]] radar imaging on 23 November 2003.<ref name="MPC-Didymos"/>

== Orbital characteristics ==
Didymos orbits the Sun at a distance of 1.0–2.3 [[Astronomical unit|AU]] once every 770 days (2 years and 1 month). Its orbit has an [[orbital eccentricity|eccentricity]] of 0.38 and an [[orbital inclination|inclination]] of 3° with respect to the [[ecliptic]]. The minimum distance between the orbit of Earth and the orbit of Didymos is currently {{Convert|0.04|AU|e6km|abbr=unit|lk=on}},<ref name="jpldata"/> but will change as the asteroid is [[Perturbation (astronomy)|perturbed]]. In November 2003 it passed 7.18 million km from Earth; it will not come that near again until November 2123, with a distance of 5.86 million km. Didymos also occasionally passes very close to Mars: it will fly by Mars at a distance of 4.68 million km in July 2144.<ref name="jpldata"/> Even the Earth approach of October 2184 is still listed with an uncertainty region of roughly ±{{val|1343|u=km}}.<ref name="Horizons2184"/>

Didymos spends 1/3 of its time orbiting in the [[near-Earth asteroid]] (NEA) region where impacts are more probable. This means that about every 73–84 thousand years, an object impacts Didymos with the energy of the [[DART (satellite)|DART mission satellite]]. Over its median NEA lifetime of 8 to 10 million years, Didymos probably has been impacted tens of times.<ref>{{Cite journal |last1=Campo Bagatin |first1=Adriano |last2=Dell’Oro |first2=Aldo |last3=Parro |first3=Laura M. |last4=Benavidez |first4=Paula G. |last5=Jacobson |first5=Seth |last6=Lucchetti |first6=Alice |last7=Marzari |first7=Francesco |last8=Michel |first8=Patrick |last9=Pajola |first9=Maurizio |last10=Vincent |first10=Jean-Baptiste |date=2024-05-03 |title=Recent collisional history of (65803) Didymos |journal=Nature Communications |language=en |volume=15 |issue=1 |pages=3714 |doi=10.1038/s41467-024-48094-7 |pmid=38702317 |issn=2041-1723|pmc=11068898 |bibcode=2024NatCo..15.3714C }}</ref>

== Physical characteristics ==
[[File:Aftermath of DART Collision with Dimorphos Captured by SOAR Telescope (noirlab2223a).jpg|thumb|left|Dust ejecta and tail of Didymos imaged in color by the [[Southern Astrophysical Research Telescope]] two days after DART's impact]]
[[File:Hubble view of Dimorphos ejecta (October 8).png|thumb|left|Double tail of Didymos imaged by the [[Hubble Space Telescope]] 12 days after DART's impact]]

In the [[SMASS classification]], Didymos was classified as an Xk-type asteroid, which transitions from the [[X-type asteroid|X-type]] to the rare [[K-type asteroid]]s.<ref name="jpldata"/> Subsequent visible and near-infrared spectroscopy showed it to be silicate in nature, which also qualifies it as a stony [[S-type asteroid]].<ref name="deLeon-2010"/> It [[rotation period|rotates]] rapidly, with a period of 2.26 hours and a low brightness variation of 0.08 [[Magnitude (astronomy)|magnitude]] ({{small|[[LCDB quality code|U=3/3]]}}), which indicates that the body has a nearly spheroidal shape.<ref name="lcdb"/><ref name="Pravec-2006"/><ref name="Pravec-2003c"/> Radar observations confirmed this spheroidal shape, showing it to be [[oblate spheroid|oblate]] due to its rapid rotation.<ref name="Naidu2020"/>

=== Satellite ===
{{Main article|Dimorphos}}
Didymos is a [[binary asteroid]] with a satellite in its orbit. The [[minor-planet moon]], named '''[[Dimorphos]]''',<ref name="Talbert2020"/> moves in a mostly circular [[retrograde orbit]]<ref>{{cite journal |doi=10.1016/j.icarus.2014.09.023|title=The binary near-Earth Asteroid (175706) 1996 FG3 — an observational constraint on its orbital evolution|journal=Icarus|volume=245|pages=56–63|year=2015|last1=Scheirich |first1=P. |last2=Pravec|first2=P. |last3=Jacobson|first3=S.A.|last4=Ďurech|first4=J. |last5=Kušnirák|first5=P. |last6=Hornoch|first6=K.|last7=Mottola|first7=S. |last8=Mommert|first8=M.|last9=Hellmich|first9=S. |last10=Pray|first10=D.|last11=Polishook |first11=D. |last12=Krugly|first12=Yu.N.|last13=Inasaridze|first13=R.Ya.|last14=Kvaratskhelia|first14=O.I.|last15=Ayvazian |first15=V.|last16=Slyusarev|first16=I. |last17=Pittichová|first17=J.|last18=Jehin|first18=E.|last19=Manfroid|first19=J.|last20=Gillon|first20=M.|last21=Galád|first21=A.|last22=Pollock|first22=J.|last23=Licandro|first23=J.|last24=Alí-Lagoa |first24=V.|last25=Brinsfield|first25=J.|last26=Molotov|first26=I.E.|arxiv=1406.4677 |bibcode=2015Icar..245...56S|s2cid=119248574 }}</ref> with an [[orbital period]] of 11.9 hours.<ref name="lcdb"/>{{efn|name=lightcurve-plot-PDO}} It measures approximately {{convert|160|m|ft|sp=us}} in diameter compared to {{convert|780|m|ft|sp=us}} for its primary (a [[mean diameter]]-ratio of 0.22).<ref name="johnstonsarchive"/> It was previously known by its [[provisional designation]] {{mp|S/2003 (65803) 1}} and had been informally called "Didymoon" or "Didymos B".<ref>"[http://phys.org/news/2015-06-telescopes-focus-esa-asteroid-mission.html Telescopes focus on target of ESA's asteroid mission] {{Webarchive|url=https://web.archive.org/web/20150818035043/http://phys.org/news/2015-06-telescopes-focus-esa-asteroid-mission.html |date=18 August 2015 }}" at phys.org (30 June 2015)</ref><ref name="Talbert2020"/>

== Naming ==
This [[minor planet]] was named "Didymos", Greek for "twin", due to its binary nature.<ref name="springer"/> The name was suggested by the discoverer, [[University of Arizona]] [[Lunar and Planetary Laboratory]] astronomer [[Joseph Montani|Joseph L. "Joe" Montani]], who made the naming proposal to the [[International Astronomical Union]] after the binary nature of the object was detected. The approved naming citation was published on 13 July 2004 ({{small|[[Minor Planet Circulars|M.P.C.]] 52326}}).<ref name="MPC-Circulars-Archive"/>

The proper name for the satellite [[Dimorphos|Didymos B]] comes from the word "Dimorphos", Greek for "having two forms".<ref name="MPEC-2020-M83"/> The meaning of the name represents how the form of Dimorphos's orbit will change after the collision with NASA’s Double Asteroid Redirection Test (DART) spacecraft,<ref name="Talbert2020"/> though in fact the change will be only a very slight change in its orbital parameters. Appropriately, Dimorphos serves dual roles as both a test target and as a part of a blueprint for a modality for future planetary protection.<ref name="Talbert2020"/> The name of the moon was suggested by planetary scientist [[Kleomenis Tsiganis]] at the [[Aristotle University of Thessaloniki]], Greece.<ref name="iau2007"/>

Two boulders (''saxa'') have been given names of traditional drums.<ref name=features>{{Cite web|url=https://planetarynames.wr.usgs.gov/SearchResults?Target=188_Didymos&Feature%20Type=57_Saxum,%20saxa|title=Nomenclature Search Results|website=planetarynames.wr.usgs.gov}}</ref>

{| class="wikitable" style="margin-left: auto; margin-right: auto; border: none;"
|+Named features
|-
! Name 
! Pronunciation !! Feature !! Named after !! Date approved<ref name=features/>
|-
| Carillon Saxum 
| {{IPAc-en|US|ˈ|k|aer|ə|l|ɒ|n}}<br>{{IPAc-en|UK|k|ə|ˈ|r|ɪ|l|j|ən}}  || boulder || [[carillon]] || 14 Nov 2023
|-
| Gong Saxum 
| {{IPAc-en|'|g|Q|N}} || boulder || [[gong]] || 14 Nov 2023
|}

== Exploration ==
[[File:Asteroid (65803) Didymos.jpg|thumb|left|Telescope image of Didymos before DART's impact]]
[[File:Dart header 2 (1).jpg|thumb|right|Artist's impression of the [[Double Asteroid Redirection Test|''DART'']] spacecraft]]
[[File:DART-impact-SAAO-Lesedi-Mookodi.gif|thumb|left|Timelapse of the Didymos system's expanding dust plume from the DART impact, as seen by the [[South African Astronomical Observatory]]'s 1-meter Lesedi telescope]]
[[File:Animation of DART trajectory around Sun.gif|thumb|right|Animation of DART's trajectory<br />{{legend2|magenta|[[Double Asteroid Redirection Test|DART]]}}{{·}}{{legend2|lime|65803 Didymos}}{{·}}{{legend2|Royalblue|[[Earth]]}}{{·}}{{legend2|yellow|[[Sun]]}}{{·}}{{legend2|cyan|2001 CB21}}{{·}}{{legend2|gold|[[3361 Orpheus]]}}]]
[[File:Animation of DART around Didymos - Impact on Dimorphos.gif|thumb|right|Animation of DART around Didymos - Impact on Dimorphos<br />{{legend2|Magenta|DART}}{{·}}{{legend2|Lime|Didymos}}{{·}}{{legend2|Gold|Dimorphos}}]]

In the early 2010s, Didymos{{'s}} moon, Dimorphos was to be the principal target of proposed robotic mission by the [[European Space Agency|ESA]] and [[NASA]], called the [[AIDA (mission)|Asteroid Impact & Deflection Assessment (AIDA) mission]]. The ESA dropped out, and the mission did not proceed.<ref name="AIDA-PDF" /><ref name="AIDA-mission" />

NASA redefined mission requirements and decided to proceed with a 2020s mission to visit Didymos with an impactor, which had been considered as a part of the earlier AIDA mission, named the [[Double Asteroid Redirection Test]] or DART. The NASA mission was intended to test whether a spacecraft impact could successfully deflect an asteroid on a collision course with Earth. The DART spacecraft was launched on 24 November 2021, and impacted Dimorphos on September 26, 2022.<ref name=nsf20220922>{{cite news |last1=Warren |first1=Haygen |title=Brace for impact: DART successfully slams into asteroid |url=https://www.nasaspaceflight.com/2022/09/dart-impact/ |date=26 September 2022 |work=[[NASASpaceFlight.com]] |access-date=27 September 2022 |archive-date=27 September 2022 |archive-url=https://web.archive.org/web/20220927001253/https://www.nasaspaceflight.com/2022/09/dart-impact/ |url-status=live }}</ref><ref name=nasa20220907>{{Cite web|date=2022-09-07|title=DART Sets Sights on Asteroid Target|url=https://www.nasa.gov/feature/dart-sets-sights-on-asteroid-target|access-date=2022-09-20|website=NASA|archive-date=21 September 2022|archive-url=https://web.archive.org/web/20220921203233/https://www.nasa.gov/feature/dart-sets-sights-on-asteroid-target/|url-status=live}}</ref><ref>{{Cite web|last=Potter|first=Sean|date=2021-11-23|title=NASA, SpaceX Launch DART: First Test Mission to Defend Planet Earth|url=http://www.nasa.gov/press-release/nasa-spacex-launch-dart-first-test-mission-to-defend-planet-earth|access-date=2021-11-25|website=NASA|archive-date=24 November 2021|archive-url=https://web.archive.org/web/20211124233245/http://www.nasa.gov/press-release/nasa-spacex-launch-dart-first-test-mission-to-defend-planet-earth/|url-status=live}}</ref> It was accompanied by the [[Italian Space Agency]]'s (ASI) six-unit [[LICIACube]] flyby [[CubeSat|Cubesat]] that was released 15 days before impact to observe the asteroid and DART's impact.<ref name=natgeo20211125>{{Cite web|last=Greshko|first=Michael|date=2021-11-23|title=This NASA spacecraft will smash into an asteroid—to practice saving Earth|url=https://www.nationalgeographic.com/science/article/nasas-dart-spacecraft-will-smash-into-an-asteroid-to-practice-saving-earth|url-status=dead|access-date=2021-11-25|website=National Geographic|language=en|archive-url=https://web.archive.org/web/20211123113703/https://www.nationalgeographic.com/science/article/nasas-dart-spacecraft-will-smash-into-an-asteroid-to-practice-saving-earth |archive-date=23 November 2021 }}</ref>

DART was the first spacecraft to intentionally target and successfully visit an asteroid known to have a [[minor-planet moon]] (The binary asteroid {{mpl|2000 DP|107}} was targeted by the [[PROCYON]] mission before it failed, [[243&nbsp;Ida]] was visited by the [[Galileo spacecraft]] but its moon was unknown until then, [[Pluto]] was considered a planet until a few months after the launch of ''[[New Horizons]]'', and [[3548&nbsp;Eurybates]]'s and [[15094&nbsp;Polymele]]'s moons were not discovered until months before and after [[Lucy (spacecraft)|''Lucy'']]'s launch, respectively). Didymos is the most easily reachable asteroid of its size from Earth, requiring a [[delta-v|delta-''v'']] of only {{Val|5.1|u=km/s}} for a spacecraft to rendezvous, compared to {{Val|6.0|u=km/s}} to reach the [[Moon]].<ref name="JPL-delta-v">{{cite web|year=2010|url=http://echo.jpl.nasa.gov/~lance/delta_v/delta_v.rendezvous.html|archive-url=https://web.archive.org/web/20010603042837/http://echo.jpl.nasa.gov/~lance/delta_v/delta_v.rendezvous.html|url-status=dead|archive-date=2001-06-03|title=Delta-v for spacecraft rendezvous with all known near-Earth asteroids|access-date=2010-10-07}}</ref>

After two weeks of analysis, NASA announced that the collision shortened Dimorphos's orbital period around Didymos by 32 minutes,<ref>{{Cite web |title=NASA says DART's asteroid impact was a huge success |url=https://www.planetary.org/articles/nasa-says-dart-impact-successful |access-date=2022-10-11 |website=The Planetary Society |language=en}}</ref> far more than the minimum requirement of 73 seconds and the success benchmark of 10 minutes. The measurement has an uncertainty of ±2 minutes.<ref name=NASA22-105>{{Cite web |title=NASA Confirms DART Mission Impact Changed Asteroid's Motion in Space |url=https://www.nasa.gov/press-release/nasa-confirms-dart-mission-impact-changed-asteroid-s-motion-in-space |access-date=2022-10-11 |website=NASA |date=11 October 2022 |language=en}}</ref>
[[File:Two LICIACube LUKE images showing the ejecta morphology that were used to reduce the possible axis orientation solutions.webp|thumb|left|Dart Impact seen by LICIACube]]
Another mission to Didymos was approved in November 2019 and launched in October 2024, with the arrival at Didymos being expected in 2026.<ref>{{Cite web |title=Planetary defence mission Hera heading for deflected asteroid |url=https://www.esa.int/Space_Safety/Hera/Planetary_defence_mission_Hera_heading_for_deflected_asteroid |access-date=2024-10-07 |website=www.esa.int |language=en}}</ref> ESA's ''[[Hera (space mission)|Hera]]'' mission is planning to survey the dynamical effects of the DART impact and measure the characteristics of the crater made by DART.<ref name="Proposed launch">[https://web.archive.org/web/20230406002045/http://iaaweb.org/iaa/Scientific%20Activity/conf/pdc2019/IAA-PDC-19-04-09ab.pdf Numerical modelling of the DART impact and the importance of the Hera mission.] Sabina D. Raducan, Thomas M. Davison, Gareth S. Collins. PDC 2019. Washington, D.C., USA.</ref>

== See also ==
* [[66391 Moshup]] – a similar near-Earth asteroid binary system
* [[List of asteroids visited by spacecraft]]
{{Clear left}}

== Notes ==
{{notelist|refs=

{{efn|name=lightcurve-plot-PDO|1=[http://www.minorplanetobserver.com/pdolc/A65803_2003.HTM Lightcurve plots] of 65803 Didymos, Palmer Divide Observatory, [[Brian D. Warner|B. D. Warner]]}}

{{efn|name=Apollo|It is an [[Apollo asteroid]] because [[perihelion]] (q) is less than 1.017 AU (Earth aphelion), not greater.}}

}} <!-- end of notelist -->

== References ==
{{reflist|refs=

<ref name="jpldata">{{cite web|type=2017-04-27 last obs.|title=JPL Small-Body Database Browser: 65803 Didymos (1996 GT)|url=https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=2065803&view=OPC|publisher=[[Jet Propulsion Laboratory]]|access-date=28 June 2017|archive-date=22 April 2021|archive-url=https://web.archive.org/web/20210422130744/https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2065803|url-status=live}} {{PD-notice}}</ref>

<ref name="deLeon-2010">{{cite journal|last1=de León|first1=J.|last2=Licandro|first2=J.|last3=Serra-Ricart|first3=M.|last4=Pinilla-Alonso|first4=N.|last5=Campins|first5=H.|title=Observations, compositional, and physical characterization of near-Earth and Mars-crosser asteroids from a spectroscopic survey|journal=Astronomy and Astrophysics|date=28 July 2010|volume=517|pages=A23|doi=10.1051/0004-6361/200913852|bibcode=2010A&A...517A..23D |doi-access=free}}
</ref>

<ref name="springer">{{cite book|title=Dictionary of Minor Planet Names – (65803) Didymos, Addendum to Fifth Edition: 2003–2005|last= Schmadel|first=Lutz D.|publisher=[[Springer Berlin Heidelberg]]|page=225
|date=2006|isbn=978-3-540-34361-5|doi=10.1007/978-3-540-34361-5_2677|chapter=(65803) Didymos &#91;1.64, 0.38, 3.4&#93;}}</ref>

<ref name="MPC-Didymos">{{cite web|title=65803 Didymos (1996 GT)|work=Minor Planet Center|url=https://www.minorplanetcenter.net/db_search/show_object?object_id=65803|access-date=12 March 2017|archive-date=12 November 2020|archive-url=https://web.archive.org/web/20201112004545/http://www.minorplanetcenter.net/db_search/show_object?object_id=65803|url-status=live}}</ref>

<ref name="MPC-Circulars-Archive">{{cite web|title=MPC/MPO/MPS Archive|work=Minor Planet Center|url=https://www.minorplanetcenter.net/iau/ECS/MPCArchive/MPCArchive_TBL.html|access-date=12 March 2017|archive-date=7 January 2022|archive-url=https://archive.today/20220107174841/https://www.minorplanetcenter.net/iau/ECS/MPCArchive/MPCArchive_TBL.html|url-status=live}}</ref>

<ref name="AIDA-PDF">{{cite web|title=AIDA: Asteroid Impact and Deflection Assessment mission under study at ESA and NASA|work=Observatoire de la Côte d'Azur|date=February 2015|url=https://www-n.oca.eu/michel/AIDA_Papers/Abstract_AstroRecon2015_PMichel.pdf|access-date=28 June 2017|archive-date=14 October 2016|archive-url=https://web.archive.org/web/20161014012223/https://www-n.oca.eu/michel/AIDA_Papers/Abstract_AstroRecon2015_PMichel.pdf|url-status=live}}</ref>

<ref name="AIDA-mission">{{cite web|title=Asteroid Impact & Deflection Assessment|url=http://m.esa.int/Our_Activities/Space_Engineering_Technology/Asteroid_Impact_Mission/Asteroid_Impact_Deflection_Assessment_mission|publisher=ESA|access-date=28 June 2017|archive-date=19 March 2018|archive-url=https://web.archive.org/web/20180319104750/https://m.esa.int/Our_Activities/Space_Engineering_Technology/Asteroid_Impact_Mission/Asteroid_Impact_Deflection_Assessment_mission|url-status=live}}</ref>

<ref name="johnstonsarchive">{{cite web|first1=Robert|last1=Johnston|title=(65803) Didymos|publisher=johnstonsarchive.net|date=20 September 2014|url=http://www.johnstonsarchive.net/astro/astmoons/am-65803.html|access-date=28 June 2017|archive-date=23 October 2020|archive-url=https://web.archive.org/web/20201023221609/https://www.johnstonsarchive.net/astro/astmoons/am-65803.html|url-status=live}}</ref>

<ref name="lcdb">{{cite web|title=LCDB Data for (65803) Didymos|publisher=Asteroid Lightcurve Database (LCDB)|url=http://www.minorplanet.info/PHP/generateOneAsteroidInfo.php?AstInfo=65803%7CDidymos|access-date=12 March 2017|archive-date=1 July 2020|archive-url=https://web.archive.org/web/20200701150205/http://www.minorplanet.info/PHP/generateOneAsteroidInfo.php?AstInfo=65803%7CDidymos|url-status=live}}</ref>

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<ref name="Nakano2022">{{cite journal |display-authors = etal |first1 = Ryota |last1 = Nakano |first2 = Masatoshi |last2 = Hirabayashi |first3 = M. |last3 = Brozovic |first4 = M. C. |last4 = Nolan |first5 = S. J. |last5 = Ostro |first6 = J. L. |last6 = Margot |title = NASA's Double Asteroid Redirection Test (DART): Mutual Orbital Period Change Due to Reshaping in the Near-Earth Binary Asteroid System (65803) Didymos |journal = The Planetary Science Journal |date = July 2022 |volume = 3 |issue = 7 |id = 148 |pages = 16 |doi = 10.3847/PSJ/ac7566 |bibcode = 2022PSJ.....3..148N |s2cid = 250327233 |doi-access = free }}</ref>

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<ref name="MPEC-2020-M83">{{cite web|title=MPEC 2020-M83 : (65803) Didymos I = Dimorphos|url=https://minorplanetcenter.net/mpec/K20/K20M83.html|work=Minor Planet Center|publisher=International Astronomical Union|date=23 June 2020|access-date=23 June 2020|archive-date=8 October 2021|archive-url=https://web.archive.org/web/20211008215116/https://minorplanetcenter.net/mpec/K20/K20M83.html|url-status=live}}</ref>

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<ref name="Horizons2184">{{cite web
  |title=Horizons Batch for 2184-Oct-14 Close Approach
  |publisher=[[JPL Horizons On-Line Ephemeris System|JPL Horizons]]
  |url=https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%2765803%27&START_TIME=%272184-Oct-14%2010:15%27&STOP_TIME=%272184-Oct-15%27&STEP_SIZE=%271%20day%27&QUANTITIES=%2720,39%27
  |archive-url=https://web.archive.org/web/20221015025813/https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%2765803%27&START_TIME=%272184-Oct-14%2010:15%27&STOP_TIME=%272184-Oct-15%27&STEP_SIZE=%271%20day%27&QUANTITIES=%2720,39%27
  |archive-date=2022-10-15
  |url-status=live
  |accessdate=2022-10-14}} RNG_3sigma = uncertainty range in km. (JPL#194/Soln.date: 2022-Oct-13 generates RNG_3sigma = 1343 km)</ref>

<ref name="Cheng2023">{{cite journal
  |display-authors = etal
  |first1 = Andrew |last1 = Cheng
  |first2 = Harrison |last2 = Agrusa
  |first3 = Brent |last3 = Barbee
  |first4 = Alex |last4 = Meyer
  |first5 = Tony |last5 = Farnham
  |first6 = Sabina |last6 = Raducan
  |title = Momentum Transfer from the DART Mission Kinetic Impact on Asteroid Dimorphos
  |url = https://assets.researchsquare.com/files/rs-2339073/v1_covered.pdf?c=1670565284
  |journal = Research Square
  |date = December 2022
  |doi = 10.21203/rs.3.rs-2339073/v1}} (This work is licensed under a CC BY 4.0 License)</ref>

}} <!-- end of reflist -->

== External links ==
{{Commons}}
* [http://www.johnstonsarchive.net/astro/asteroidmoons.html Asteroids with Satellites], Robert Johnston, johnstonsarchive.net
* [https://www.minorplanetcenter.net/iau/lists/NumberedMPs065001.html Discovery Circumstances: Numbered Minor Planets (65001)-(70000)] – Minor Planet Center
* {{NeoDys|65803}}
* {{JPL small body}}

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