Double Asteroid Redirection Test#Secondary spacecraft

NASA and the European Space Agency (ESA) started with individual plans for missions to test asteroid deflection strategies, but by 2015, they struck a collaboration called AIDA (Asteroid Impact and Deflection Assessment) involving two separate spacecraft launches that would work in synergy.[http://dart.jhuapl.edu/ AIDA DART] Home page at APL{{Cite web |title=Asteroid Impact & Deflection Assessment (AIDA) study |url=http://www.esa.int/Our_Activities/Space_Engineering_Technology/NEO/Asteroid_Impact_Deflection_Assessment_AIDA_study |url-status=dead |archive-url=https://web.archive.org/web/20150607004851/http://www.esa.int/Our_Activities/Space_Engineering_Technology/NEO/Asteroid_Impact_Deflection_Assessment_AIDA_study |archive-date=7 June 2015}}[http://dart.jhuapl.edu/Mission/index.php DART] at Applied Physics Laboratory Johns Hopkins University Under that proposal, the European Asteroid Impact Mission (AIM), would have launched in December 2020, and DART in July 2021. AIM would have orbited the larger asteroid to study its composition and that of its moon. DART would then kinetically impact the asteroid's moon on 26 September 2022, during a close approach to Earth.

The AIM orbiter was however canceled, then replaced by Hera which plans to start observing the asteroid four years after the DART impact. Live monitoring of the DART impact thus had to be obtained from ground-based telescopes and radar.

In June 2017, NASA approved a move from concept development to the preliminary design phase,{{Cite web |last1=Brown |first1=Geoff |last2=University |first2=Johns Hopkins |title=NASA plans to test asteroid deflection technique designed to prevent Earth impact |url=https://phys.org/news/2017-07-nasa-asteroid-deflection-technique-earth.html |website=phys.org}} and in August 2018 the start of the final design and assembly phase of the mission.[https://phys.org/news/2018-09-asteroid-deflection-mission-key-milestone.html Asteroid-deflection mission passes key development milestone] 7 September 2018 On 11 April 2019, NASA announced that a SpaceX Falcon 9 would be used to launch DART.{{Cite web |date=12 April 2019 |title=NASA Awards Launch Services Contract for Asteroid Redirect Test Mission |url=https://www.nasa.gov/press-release/nasa-awards-launch-services-contract-for-asteroid-redirect-test-mission |access-date=12 April 2019 |publisher=NASA}} {{PD-notice}}

Satellite impact on a small Solar System body had already been implemented once, by NASA's {{convert|372|kg|lb|adj=on}} Deep Impact space probe's impactor spacecraft and for a completely different purpose (analysis of the structure and composition of a comet). On impact, Deep Impact released 19 gigajoules of energy (the equivalent of 4.8 tons of TNT),{{Cite web |title=NASA – Deep Impact's Impactor |url=https://www.nasa.gov/mission_pages/deepimpact/spacecraft/impactor.html |url-status=dead |archive-url=https://web.archive.org/web/20160623220100/http://www.nasa.gov/mission_pages/deepimpact/spacecraft/impactor.html |archive-date=23 June 2016 |website=nasa.gov}} and excavated a crater up to {{convert|150|m}} wide.{{cite web |title=In Depth - Deep Impact (EPOXI) |url=https://solarsystem.nasa.gov/missions/deep-impact-epoxi/in-depth/ |website=NASA Solar System Exploration |date=30 November 2017 |access-date=11 October 2022}}

The DART spacecraft was an impactor with a mass of {{convert|610|kg}}{{Cite web |date=28 October 2021 |title=Double Asteroid Redirection Test (DART) |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=DART |access-date=5 November 2021 |publisher=NASA}} {{PD-notice}} that hosted no scientific payload and had sensors only for navigation. The spacecraft cost US$330 million by the time it collided with Dimorphos in 2022.

File:DRACO intergration to DART.jpg

DART's navigation sensors included a Sun sensor, a star tracker called SMART Nav software (Small-body Maneuvering Autonomous Real Time Navigation),{{Cite web |title=DART |url=https://dart.jhuapl.edu/Mission/Impactor-Spacecraft.php |access-date=20 May 2022 |website=dart.jhuapl.edu |language=en}} and a {{convert|20|cm|in|adj=on}} aperture camera called Didymos Reconnaissance and Asteroid Camera for Optical navigation (DRACO). DRACO was based on the Long Range Reconnaissance Imager (LORRI) onboard New Horizons spacecraft, and supported autonomous navigation to impact the asteroid's moon at its center. The optical part of DRACO was a Ritchey-Chrétien telescope with a field of view of 0.29° and a focal length of 2.6208 m (f/12.60). The spatial resolution of the images taken immediately before the impact was around 20 centimeters per pixel. The instrument had a mass of {{convert|8.66|kg}}.{{Cite conference |last1=Fletcher |first1=Zachary |last2=Ryan |first2=Kyle |last3=Maas |first3=Bryan |last4=Dickman |first4=Joseph |last5=Hammond |first5=Randolph |last6=Bekker |first6=Dmitriy |last7=Nelson |first7=Tyler |last8=Mize |first8=James |last9=Greenberg |first9=Jacob |date=6 July 2018 |title=Design of the Didymos Reconnaissance and Asteroid Camera for OpNav (DRACO) on the double asteroid redirection test (DART) |url=https://www.spiedigitallibrary.org/conference-proceedings-of-spie/10698/2310136/Design-of-the-Didymos-reconnaissance-and-asteroid-camera-for-OpNav/10.1117/12.2310136.short?SSO=1 |conference=Space Telescopes and Instrumentation 2018: Optical, Infrared, and Millimeter Wave |location=Austin, TX |publisher=Proceedings of SPIE 10698 |volume=106981X |doi=10.1117/12.2310136 |first10=Wendy |last10=Hunt |first11=Stephen |last11=Smee |first12=Nancy |last12=Chabot |first13=Andrew |last13=Cheng|url-access=subscription }}

The detector used in the camera was a CMOS image sensor measuring 2,560 × 2,160 pixels. The detector records the wavelength range from 0.4 to 1 micron (visible and near infrared). A commercial off-the-shelf CMOS detector was used instead of a custom charge-coupled device in LORRI. DRACO's detector performance actually met or exceeded that of LORRI because of the improvements in sensor technology in the decade separating the design of LORRI and DRACO.{{Cite web |last=Lakdawalla |first=Emily |date=22 September 2022 |title=DART Impact on Monday! |url=https://www.patreon.com/posts/dart-impact-on-72349462 |access-date=26 September 2022 |via=Patreon}} Fed into an onboard computer with software descended from anti-missile technology, the DRACO images helped DART autonomously guide itself to its crash.{{Cite web |last=Lakdawalla |first=Emily |date=23 September 2022 |title=NASA's DART Mission to Impact Asteroid Monday |url=https://skyandtelescope.org/astronomy-news/nasas-dart-mission-to-impact-asteroid/ |access-date=26 September 2022 |website=Sky & Telescope |language=en-US}}

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|image1 = Behind_the_Scenes_Inspecting_DART's_Roll_Out_Solar_Array_ROSA_Technology.webm

|image2 = Transformational Solar Array experiment on DART's Roll Out Solar Array (ROSA).png

|footer = The spacecraft's solar arrays used a Roll Out Solar Array (ROSA) design, that was tested on the International Space Station (ISS) in June 2017 as part of Expedition 52.{{Cite news |last=Talbert |first=Tricia |date=30 June 2017 |title=Double Asteroid Redirection Test (DART) Mission |publisher=NASA |url=https://www.nasa.gov/planetarydefense/dart |access-date=21 January 2018}} {{PD-notice}}

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Using ROSA as the structure, a small portion of the DART solar array was configured to demonstrate Transformational Solar Array technology, which has very-high-efficiency SolAero Inverted Metamorphic (IMM) solar cells and reflective concentrators providing three times more power than other available solar array technology.{{citation|url=https://www.youtube.com/watch?v=UmSdzC93H7c|title=Behind the Scenes: Inspecting DART's Roll-Out Solar Array (ROSA) Technology|date=12 August 2021 |access-date=13 August 2021}}; {{Cite web |title=DART has a solar array experiment called transformational solar array on its roll out solar array panel |url=https://dart.jhuapl.edu/Mission/Impactor-Spacecraft.php |url-status=live |archive-url=https://web.archive.org/web/20191223144842/https://dart.jhuapl.edu/Mission/Impactor-Spacecraft.php |archive-date=23 December 2019 |access-date=13 August 2021 |website=dart.jhuapl.edu}}

The DART spacecraft was the first spacecraft to use a new type of high-gain communication antenna, a Spiral Radial Line Slot Array (RLSA). The circularly-polarized antenna operated at the (microwave) X-band NASA Deep Space Network (NASA DSN) frequencies of 7.2 and 8.4 GHz, and had a gain of 29.8 dBi on downlink and 23.6 dBi on uplink. The fabricated antenna in a flat and compact shape exceeded the given requirements and was tested through environments resulting in a TRL-6 design.{{Cite book |last=Bray |first=Matthew |title=2020 IEEE International Symposium on Antennas and Propagation and North American Radio Science Meeting |year=2020 |isbn=978-1-7281-6670-4 |pages=379–380 |chapter=A Spiral Radial Line Slot Array Antenna for NASA's Double Asteroid Redirection Test (DART) |doi=10.1109/IEEECONF35879.2020.9330400 |s2cid=231975847}}File:NASA NEXT Ion thruster.712983main NEXT LDT Thrusterhi-res full.jpg)]]

DART demonstrated the NEXT gridded ion thruster, a type of solar electric propulsion.[https://www.nasa.gov/planetarydefense/dart Planetary Defense: Double Asteroid Redirection Test (DART) Mission] NASA 2017 {{PD-notice}}{{Cite book |last=Kantsiper |first=Brian |title=2017 IEEE Aerospace Conference |year=2017 |isbn=978-1-5090-1613-6 |pages=1–7 |chapter=The Double Asteroid Redirection Test (DART) mission electric propulsion trade |doi=10.1109/AERO.2017.7943736 |s2cid=43072949}} It was powered by {{convert|22|m2|adj=on}} solar arrays to generate the approximately 3.5 kW needed to power the NASA Evolutionary Xenon Thruster–Commercial (NEXT-C) engine.{{Cite book |last1=Adams |first1=Elena |title=2019 IEEE Aerospace Conference |last2=Oshaughnessy |first2=Daniel |last3=Reinhart |first3=Matthew |last4=John |first4=Jeremy |last5=Congdon |first5=Elizabeth |last6=Gallagher |first6=Daniel |last7=Abel |first7=Elisabeth |last8=Atchison |first8=Justin |last9=Fletcher |first9=Zachary |year=2019 |isbn=978-1-5386-6854-2 |pages=1–11 |chapter=Double Asteroid Redirection Test: The Earth Strikes Back |doi=10.1109/AERO.2019.8742007 |last10=Chen |first10=Michelle |last11=Heistand |first11=Christopher |last12=Huang |first12=Philip |last13=Smith |first13=Evan |last14=Sibol |first14=Deane |last15=Bekker |first15=Dmitriy |last16=Carrelli |first16=David |s2cid=195222414}} Early tests of the ion thruster revealed a reset mode that induced higher current (100 A) in the spacecraft structure than expected (25 A). It was decided not to use the ion thruster further as the mission could be accomplished without it, using conventional thrusters fueled by the {{convert|110|lb|kg|order=flip}} of hydrazine onboard.{{cite web |title=Impactor Spacecraft |url=https://dart.jhuapl.edu/Mission/Impactor-Spacecraft.php |website=DART |publisher=The Johns Hopkins University |access-date=24 November 2022}} However, the ion thrusters remained available if needed to deal with contingencies, and had DART missed its target, the ion system could have returned DART to Dimorphos two years later.[https://www.youtube.com/watch?v=fsZo1cxMqck NASA's DART Mission Post-Asteroid-Impact News Briefing], 26 September 2022, 8pm EDT, at 27 minutes

File:LICIACube CubeSat a companion satellite of Dart Spacecraft.jpg CubeSat, a companion satellite of the DART spacecraft]]

{{Main Article|LICIACube}}

The Italian Space Agency (ASI) contributed a secondary spacecraft called LICIACube (Light Italian CubeSat for Imaging of Asteroids), a small CubeSat that piggybacked with DART and separated on 11 September 2022, 15 days before impact. It acquired images of the impact and ejecta as it drifted past the asteroid.[http://dart.jhuapl.edu/News-and-Resources/blog.php?id=20180927 Asteroids have been hitting the Earth for billions of years. In 2022, we hit back.] {{webarchive|url=https://web.archive.org/web/20181031133108/http://dart.jhuapl.edu/News-and-Resources/blog.php?id=20180927 |date=31 October 2018}} Andy Rivkin, The Johns Hopkins University Applied Physics Laboratory, 27 September 2018{{Cite web |last1=Kretschmar |first1=Peter |last2=Küppers |first2=Michael |date=20 December 2018 |title=The CubeSat Revolution |url=https://www.cosmos.esa.int/documents/13611/1603502/20181220_cubesats.pdf#page=34 |access-date=24 January 2019 |publisher=ESA}} LICIACube communicated directly with Earth, sending back images of the ejecta after the Dimorphos flyby.{{Cite web |last=Cheng |first=Andy |date=15 November 2018 |title=DART Mission Update |url=https://www.cosmos.esa.int/documents/1786001/1845930/4.+DART+Overview+%28A.+Cheng%29.pdf/da9935f1-74b7-9316-e9af-0fb2cc63197c |access-date=14 January 2019 |publisher=ESA}} LICIACube is equipped with two optical cameras, dubbed LUKE and LEIA.{{Cite web |title=LICIACube |url=https://www.asi.it/en/planets-stars-universe/solar-system-and-beyond/liciacube/ |access-date=26 November 2021 |publisher=ASI}}

File:Animation of DART around Didymos - Impact on Dimorphos.gif

The spacecraft hit Dimorphos in the direction opposite to the asteroid's motion. Following the impact, the instantaneous orbital speed of Dimorphos therefore dropped slightly, which reduced the radius of its orbit around Didymos. The trajectory of Didymos was also modified, but in inverse proportion to the ratio of its mass to the much lower mass of Dimorphos and therefore not much. The actual velocity change and orbital shift depended on the topography and composition of the surface, among other things. The contribution of the recoil momentum from the impact ejecta produces a poorly predictable "momentum enhancement" effect.{{Citation |title=WATCH: NASA Asteroid Redirection Test Media Briefing – Livestream | date=4 November 2021 |url=https://www.youtube.com/watch?v=EMwB0QERjEw |language=en |access-date=20 May 2022}} Before the impact, the momentum transferred by DART to the largest remaining fragment of the asteroid was estimated as up to 3–5 times the incident momentum, depending on how much and how fast material would be ejected from the impact crater. Obtaining accurate measurements of that effect was one of the mission's main goals and will help refine models of future impacts on asteroids.{{Cite journal |last1=Rivkin |first1=Andrew S. |last2=Chabot |first2=Nancy L. |last3=Stickle |first3=Angela M. |last4=Thomas |first4=Cristina A. |last5=Richardson |first5=Derek C. |last6=Barnouin |first6=Olivier |last7=Fahnestock |first7=Eugene G. |last8=Ernst |first8=Carolyn M. |last9=Cheng |first9=Andrew F. |last10=Chesley |first10=Steven |last11=Naidu |first11=Shantanu |date=25 August 2021 |title=The Double Asteroid Redirection Test (DART): Planetary Defense Investigations and Requirements |journal=The Planetary Science Journal |volume=2 |issue=5 |page=173 |bibcode=2021PSJ.....2..173R |doi=10.3847/PSJ/ac063e |issn=2632-3338 |s2cid=237301576|doi-access=free }}

The DART impact excavated surface/subsurface materials of Dimorphos, leading to the formation of a crater and/or some magnitude of reshaping (i.e., shape change without significant mass loss). Some of the ejecta may eventually hit Didymos's surface. If the kinetic energy delivered to its surface was high enough, reshaping may have also occurred in Didymos, given its near-rotational-breakup spin rate. Reshaping on either body would have modified their mutual gravitational field, leading to a reshaping-induced orbital period change, in addition to the impact-induced orbital period change. If left unaccounted for, this could later have led to an erroneous interpretation of the effect of the kinetic deflection technique.{{Cite journal |last1=Nakano |first1=Ryota |last2=Hirabayashi |first2=Masatoshi |last3=Agrusa |first3=Harrison F. |last4=Ferrari |first4=Fabio |last5=Meyer |first5=Alex J. |last6=Michel |first6=Patrick |last7=Raducan |first7=Sabina D. |last8=Sánchez |first8=Paul |last9=Zhang |first9=Yun |date=5 July 2022 |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 |language=en |volume=3 |issue=7 |pages=148 |doi=10.3847/PSJ/ac7566 |bibcode=2022PSJ.....3..148N |s2cid=250327233 |issn=2632-3338|doi-access=free |hdl=11311/1223308 |hdl-access=free }}

File:Telescopes observing DART's impact.png

File:Aftermath of DART Collision with Dimorphos Captured by SOAR Telescope (noirlab2223a).jpg shows the vast plume of dust and debris blasted from the surface of the asteroid Dimorphos]]

DART's companion LICIACube,[https://twitter.com/LICIACube LICIACube Twitter feed]{{cite news|url=https://gizmodo.com/liciacube-images-dart-asteroid-impact-1849585958 |title=First Asteroid Impact Images from DART's Companion Show Tentacle-Like Debris Plume|author=George Dvorsky|date=September 27, 2022|publisher=Gizmodo}} the Hubble Space Telescope, James Webb Space Telescope, and the Earth-based ATLAS observatory all detected the ejecta plume from the DART impact.[https://twitter.com/fallingstarIfA ATLAS twitter feed]{{cite news|url=https://gizmodo.com/telescopes-capture-dart-asteroid-impact-1849585394|title=Ground Telescopes Capture Jaw-Dropping Views of DART Asteroid Impact|

quote=Telescopes around the world honed in on the historic collision, revealing a surprisingly large and bright impact plume.|author=George Dvorsky|date=September 27, 2022|publisher=Gizmodo}} On September 26, SOAR observed the visible impact trail to be over {{convert|10000|km|LD mi}} long.{{cite news |last1=Strickland |first1=Ashley |title=Comet-like debris trail spotted after spacecraft crashes into asteroid |url=https://www.cnn.com/2022/10/04/world/nasa-dart-debris-trail-scn/index.html |access-date=6 October 2022 |work=CNN |date=4 October 2022 |language=en}} Initial estimates of the change in binary orbit period were expected within a week and with the data released by LICIACube.{{Cite web |title=DART: Asteroid – eoPortal Directory – Satellite Missions |url=https://directory.eoportal.org/web/eoportal/satellite-missions/d/dart-asteroid |access-date=24 November 2021 |website=directory.eoportal.org}} DART's mission science depends on careful Earth-based monitoring of the orbit of Dimorphos over the subsequent days and months. Dimorphos was too small and too close to Didymos for almost any observer to see directly, but its orbital geometry is such that it transits Didymos once each orbit and then passes behind it half an orbit later. Any observer that can detect the Didymos system therefore sees the system dim and brighten again as the two bodies cross.

The impact was planned for a moment when the distance between Didymos and Earth is at a minimum, permitting many telescopes to make observations from many locations. The asteroid was near opposition and visible high in the night sky well into 2023. The change in Dimorphos's orbit around Didymos was detected by optical telescopes watching mutual eclipses of the two bodies through photometry on the Dimorphos-Didymos pair. In addition to radar observations, they confirmed that the impact shortened Dimorphos's orbital period by 32 minutes.{{cite web |last1=Nelson |first1=Bill |last2=Saccoccia |first2=Giorgio |title=Update on DART Mission to Asteroid Dimorphos (NASA News Conference) |url=https://www.youtube.com/watch?v=Zhzn0U2m5wQ |website=YouTube |date=11 October 2022 |access-date=11 October 2022 |language=en}} Based on the shortened binary orbital period, the instantaneous reduction in Dimorphos's velocity component along its orbital track was determined, which indicated that substantially more momentum was transferred to Dimorphos from the escaping impact ejecta than from the impact itself. In this way, the DART kinetic impact was highly effective in deflecting Dimorphos.{{cite journal | vauthors=Cheng AF, Agrusa HF, Barbee BW, Meyer AJ | display-authors =3|title=Momentum transfer from the DART mission kinetic impact on asteroid Dimorphos |journal=Nature |date=1 March 2023 | volume =616| issue =7957| pages =457–460|doi=10.1038/s41586-023-05878-z | pmid =36858075| pmc =10115652| arxiv =2303.03464| bibcode =2023Natur.616..457C| s2cid =257282972}}

In a collaborating project, the European Space Agency has developed Hera, a spacecraft that was launched to Didymos in October 2024[https://room.eu.com/news/hera-mission-is-approved-as-esa-receives-biggest-ever-budget Hera mission is approved as ESA receives biggest ever budget] Kerry Hebden Room Space Journal 29 November 2019{{Cite news |last=Bergin |first=Chris |date=7 January 2019 |title=Hera adds objectives to planetary defense test mission |publisher=NASASpaceflight.com |url=https://www.nasaspaceflight.com/2019/01/hera-objectives-planetary-defense-mission/ |access-date=11 January 2019}} and planned to arrive in 2026{{Cite journal|title=The ESA Hera Mission: Detailed Characterization of the DART Impact Outcome and of the Binary Asteroid (65803) Didymos|first1=Patrick|last1=Michel|first2=Michael|last2=Küppers|first3=Adriano Campo|last3=Bagatin|first4=Benoit|last4=Carry|first5=Sébastien|last5=Charnoz|first6=Julia de|last6=Leon|first7=Alan|last7=Fitzsimmons|first8=Paulo|last8=Gordo|first9=Simon F.|last9=Green|first10=Alain|last10=Hérique|first11=Martin|last11=Juzi|first12=Özgür|last12=Karatekin|first13=Tomas|last13=Kohout|first14=Monica|last14=Lazzarin|first15=Naomi|last15=Murdoch|first16=Tatsuaki|last16=Okada|first17=Ernesto|last17=Palomba|first18=Petr|last18=Pravec|first19=Colin|last19=Snodgrass|first20=Paolo|last20=Tortora|first21=Kleomenis|last21=Tsiganis|first22=Stephan|last22=Ulamec|first23=Jean-Baptiste|last23=Vincent|first24=Kai|last24=Wünnemann|first25=Yun|last25=Zhang|first26=Sabina D.|last26=Raducan|first27=Elisabetta|last27=Dotto|first28=Nancy|last28=Chabot|first29=Andy F.|last29=Cheng|first30=Andy|last30=Rivkin|first31=Olivier|last31=Barnouin|first32=Carolyn|last32=Ernst|first33=Angela|last33=Stickle|first34=Derek C.|last34=Richardson|first35=Cristina|last35=Thomas|first36=Masahiko|last36=Arakawa|first37=Hirdy|last37=Miyamoto|first38=Akiko|last38=Nakamura|first39=Seiji|last39=Sugita|first40=Makoto|last40=Yoshikawa|first41=Paul|last41=Abell|first42=Erik|last42=Asphaug|first43=Ronald-Louis|last43=Ballouz|first44=William F.|last44=Bottke|first45=Dante S.|last45=Lauretta|first46=Kevin J.|last46=Walsh|first47=Paolo|last47=Martino|first48=Ian|last48=Carnelli|date=15 July 2022|journal=The Planetary Science Journal|volume=3|issue=7|pages=160|doi=10.3847/PSJ/ac6f52|bibcode=2022PSJ.....3..160M |s2cid=250599919 |doi-access=free|hdl=10045/125568|hdl-access=free}}[https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=4372&context=smallsat The Juventas CubeSat in Support of ESA's Hera Mission to the Asteroid Didymos.] Hannah R. Goldberg, Özgür Karatekin, Birgit Ritter, Alain Herique, Paolo Tortora, Claudiu Prioroc, Borja Garcia Gutierrez, Paolo Martino, Ian Carnelli. 33rd Annual AIAA/USU Conference on Small Satellites. to do a detailed reconnaissance and assessment. Hera carries two CubeSats, Milani and Juventas.

{{excerpt|AIDA (international space cooperation)|AIDA mission architecture|hat=no}}

File:65803 didymos model.png, based on photometric light curve and radar data]]

The mission's target was Dimorphos in 65803 Didymos system, a binary asteroid system in which one asteroid is orbited by a smaller one. The primary asteroid (Didymos A) is about {{convert|780|m}} in diameter; the asteroid moon Dimorphos (Didymos B) is about {{convert|160|m}} in diameter in an orbit about {{convert|1|km|mi}} from the primary. The mass of the Didymos system is estimated at 528 billion kg, with Dimorphos comprising 4.8 billion kg of that total. Choosing a binary asteroid system is advantageous because changes to Dimorphos's velocity can be measured by observing when Dimorphos subsequently passes in front of its companion, causing a dip in light that can be seen by Earth telescopes. Dimorphos was also chosen due to its appropriate size; it is in the size range of asteroids that one would want to deflect, were they on a collision course with Earth. In addition, the binary system was relatively close to the Earth in 2022, at about {{convert|7|e6mi|AU LD e6km|sp=us|abbr=off}}.{{Cite news |date=23 November 2021 |title=Seen the film Armageddon? NASA's aiming to smash an asteroid off course in real life |language=en-AU |work=Australian Broadcasting Corporation (ABC) |url=https://www.abc.net.au/news/science/2021-11-24/nasa-dart-mission-deflect-asteroid-armageddon/100574146 |access-date=24 September 2022}} The Didymos system is not an Earth-crossing asteroid, and there is no possibility that the deflection experiment could create an impact hazard.{{Cite journal |last1=Michel |first1=P. |last2=Cheng |first2=A. |last3=Carnelli |first3=I. |last4=Rivkin |first4=A. |last5=Galvez |first5=A. |last6=Ulamec |first6=S. |last7=Reed |first7=C. |last8=AIDA Team |date=8 January 2015 |title=AIDA: Asteroid impact and deflection assessment mission under study at ESA and NASA |url=https://elib.dlr.de/95095/ |journal=Spacecraft Reconnaissance of Asteroid and Comet Interiors |volume=1829 |page=6008 |bibcode=2015LPICo1829.6008M}} On 4 October 2022, Didymos made an Earth approach of {{convert|10.6|e6km|au LD e6mi|abbr=off}}.{{cite report |title=65803 Didymos |series=JPL Small-Body Database Browser |publisher=NASA / Jet Propulsion Laboratory |url=https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=2065803&view=OPC |access-date=2021-12-30 |via=ssd.jpl.nasa.gov}}

File:DART inside the payload fairing (KSC-20211116-PH-EGW01 0001).jpg on 16 November 2021]]

Launch preparations for DART began on 20 October 2021, as the spacecraft began fueling at Vandenberg Space Force Base (VSFB) in California.{{Cite web |date=20 October 2021 |title=Spacecraft for asteroid deflection experiment ready for fueling at Vandenberg |url=https://spaceflightnow.com/2021/10/20/spacecraft-for-asteroid-deflection-experiment-ready-for-fueling-at-vandenberg/ |access-date=5 November 2021 |publisher=Spaceflight Now}} The spacecraft arrived at Vandenberg in early October 2021 after a cross-country drive. DART team members prepared the spacecraft for flight, testing the spacecraft's mechanisms and electrical system, wrapping the final parts in multilayer insulation blankets and practicing the launch sequence from both the launch site and the mission operations center at APL. DART headed to the SpaceX Payload Processing Facility on VSFB on 26 October 2021. Two days later, the team received the green light to fill DART's fuel tank with roughly {{convert|50|kg}} of hydrazine propellant for spacecraft maneuvers and attitude control. DART also carried about {{convert|60|kg}} of xenon for the NEXT-C ion engine. Engineers loaded the xenon before the spacecraft left APL in early October 2021.{{Cite web |date=3 November 2021 |title=NASA's DART Preps for Launch in First Planetary Defense Test Mission |url=https://www.nasa.gov/feature/nasa-s-dart-prepares-for-launch-in-first-planetary-defense-test-mission |access-date=24 November 2021 |publisher=NASA}} {{PD-notice}}

Starting on 10 November 2021, engineers mated the spacecraft to the adapter that stacks on top of the SpaceX Falcon 9 launch vehicle. The Falcon 9 rocket without the payload fairing rolled for a static fire and later came back to the processing facility again where technicians with SpaceX installed the two halves of the fairing around the spacecraft over the course of two days, 16 and 17 November, inside the SpaceX Payload Processing Facility at Vandenberg Space Force Base and the ground teams completed a successful Flight Readiness Review later that week with the fairing then attached to the rocket.{{Cite web |title=NASA's DART Spacecraft Secured in Payload Fairing, Flight Readiness Review Complete – Double Asteroid Redirection Test (DART) Mission |url=https://blogs.nasa.gov/dart/2021/11/22/nasas-dart-spacecraft-secured-in-payload-fairing-flight-readiness-review-complete/ |access-date=24 November 2021 |website=blogs.nasa.gov|date=22 November 2021 }} {{PD-notice}}

A day before launch, the launch vehicle rolled out of the hangar and onto the launch pad at Vandenberg Space Launch Complex 4 (SLC-4E); from there, it lifted off to begin DART's journey to the Didymos system and it propelled the spacecraft into space.

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{{multiple image

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| image1= DART Launch (NHQ202111230022).jpg

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The DART spacecraft was launched on 24 November 2021, at 06:21:02 UTC.

Early planning suggested that DART was to be deployed into a high-altitude, high-eccentricity Earth orbit designed to avoid the Moon. In such a scenario, DART would use its low-thrust, high-efficiency NEXT ion engine to slowly escape from its high Earth orbit to a slightly inclined near-Earth solar orbit, from which it would maneuver onto a collision trajectory with its target. But because DART was launched as a dedicated Falcon 9 mission, the payload along with Falcon 9's second stage was placed directly on an Earth escape trajectory and into heliocentric orbit when the second stage reignited for a second engine startup or escape burn. Thus, although DART carries a first-of-its-kind electric thruster and plenty of xenon fuel, Falcon 9 did almost all of the work, leaving the spacecraft to perform only a few trajectory-correction burns with simple chemical thrusters as it homed in on Didymos's moon Dimorphos.{{Cite journal |last1=Atchison |first1=Justin A. |last2=Ozimek |first2=Martin T. |last3=Kantsiper |first3=Brian L. |last4=Cheng |first4=Andrew F. |date=1 June 2016 |title=Trajectory options for the DART mission |url=https://www.sciencedirect.com/science/article/pii/S0094576515303040 |journal=Acta Astronautica |series=Special Section: Selected Papers from the International Workshop on Satellite Constellations and Formation Flying 2015 |volume=123 |pages=330–339 |bibcode=2016AcAau.123..330A |doi=10.1016/j.actaastro.2016.03.032 |issn=0094-5765|url-access=subscription }}

File:Animation of DART trajectory around Sun.gif}}{{·}}{{legend2|Royalblue|Earth}}{{·}}{{legend2|yellow|Sun}}{{·}}{{legend2|cyan|{{mpl|2001 CB|21}}}}{{·}}{{legend2|gold|3361 Orpheus}}]]

The transit phase before impact lasted about 9 months. During its interplanetary travel, the DART spacecraft made a distant flyby of the {{convert|578|m|ft|abbr=off|adj=on}} diameter near-Earth asteroid {{mpl|(138971) 2001 CB|21}} in March 2022.{{Cite web |title=Double Asteroid Redirection Test (DART) |url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=2021-110A |access-date=25 September 2022 |website=NASA Space Science Data Coordinated Archive |publisher=NASA}}; {{cite web|title=Asteroids have been hitting the Earth for billions of years. In 2022, we hit back.|url=https://dart.jhuapl.edu/News-and-Resources/article.php?id=20180927|first=Andy|last=Rivkin|work=DART|publisher=Johns Hopkins University Applied Physics Laboratory|date=27 September 2018|accessdate=25 September 2022}} DART passed {{convert|0.117|AU|LD e6km e6mi|abbr=off}} from {{mp|2001 CB|21}} in its closest approach on 2 March 2022.{{Cite web |title=JPL Horizons On-Line Ephemeris for 138971 (2001 CB21) on 2022-Mar-01 to 2022-Mar-03 |url=https://ssd.jpl.nasa.gov/api/horizons.api?format=text&COMMAND=%27138971%27&OBJ_DATA=%27YES%27&MAKE_EPHEM=%27YES%27&EPHEM_TYPE=%27OBSERVER%27&CENTER=%27500@-135%27&START_TIME=%272022-03-01%27&STOP_TIME=%272022-03-03%27&STEP_SIZE=%271h%27&QUANTITIES=%271,9,20,23%27&RANGE_UNITS=%27KM%27 |access-date=28 September 2022 |website=JPL Horizons On-Line Ephemeris System |publisher=Jet Propulsion Laboratory}} Ephemeris Type: Observer. Target Body: 138971 (2001 CB21). Observer Location: 500@-135 (DART Spacecraft).

DART's DRACO camera opened its aperture door and took its first light image of some stars on 7 December 2021, when it was {{convert|2|e6mi|AU LD e6km|abbr=off}} away from Earth.{{Cite web |last=Talbert |first=Tricia |date=22 December 2021 |title=NASA's DART Captures One of Night Sky's Brightest Stars |url=https://www.nasa.gov/feature/with-its-single-eye-nasa-s-dart-returns-first-images-from-space/ |access-date=25 September 2022 |publisher=NASA}} The stars in DRACO's first light image were used as calibration for the camera's pointing before it could be used to image other targets. On 10 December 2021, DRACO imaged the open cluster Messier 38 for further optical and photometric calibration.

On 27 May 2022, DART observed the bright star Vega with DRACO to test the camera's optics with scattered light.{{Cite web |last=Talbert |first=Tricia |date=17 June 2022 |title=NASA's DART Captures One of Night Sky's Brightest Stars |url=https://www.nasa.gov/feature/nasa-s-dart-captures-one-of-night-sky-s-brightest-stars |access-date=25 September 2022 |publisher=NASA}} On 1 July and 2 August 2022, DART's DRACO imager observed Jupiter and its moon Europa emerging from behind the planet, as a performance test for the SMART Nav tracking system to prepare for the Dimorphos impact.{{Cite web |last=Talbert |first=Tricia |date=22 September 2022 |title=DART Tests Autonomous Navigation System Using Jupiter and Europa |url=https://www.nasa.gov/feature/dart-tests-autonomous-navigation-system-using-jupiter-and-europa/ |access-date=25 September 2022 |publisher=NASA}}

Two months before the impact, on 27 July 2022, the DRACO camera detected the Didymos system from approximately {{convert|32|e6km|AU LD e6mi|abbr=off}} away and started refining its trajectory. The LICIACube nanosatellite was released on 11 September 2022, 15 days before the impact.{{Cite web |last=Keeter |first=Bill |date=14 September 2022 |title=DART's Small Satellite Companion Takes Flight Ahead of Impact |url=https://www.nasa.gov/feature/dart-s-small-satellite-companion-takes-flight-ahead-of-impact |access-date=25 September 2022 |publisher=NASA}} Four hours before impact, some {{convert|90000|km|LD mi}} away, DART began to operate in complete autonomy under control of its SMART Nav guidance system. Three hours before impact, DART performed an inventory of objects near the target. Ninety minutes before the collision, when DART was {{convert|38000|km|LD mi}} away from Dimorphos, the final trajectory was established.{{Cite web |date=26 September 2022 |title=NASA's DART Mission Hits Asteroid in First-Ever Planetary Defense Test |url=https://www.nasa.gov/press-release/nasa-s-dart-mission-hits-asteroid-in-first-ever-planetary-defense-test}} When DART was {{convert|24000|km|LD mi}} away Dimorphos became discernible (1.4 pixels) through the DRACO camera which then continued to capture images of the asteroid's surface and transmit them in real-time.{{cite web|first=T.|last=Statler|title=Session 3: DART|url=https://www.unoosa.org/documents/pdf/smpag/PDC2021_Presentation_Day1/IAA-PDC-21-03-MASTERFILE.pdf|access-date=November 5, 2022|publisher=7th IAA Planetary Defense Conference}}

DRACO was the only instrument able to provide a detailed view of Dimorphos's surface. The use of DART's thrusters caused vibrations throughout the spacecraft and solar panels, resulting in blurred images. To ensure sharp images, the last trajectory correction was executed 4 minutes before impact and the thrusters were deactivated afterwards.

File:Dart impact replay.webm

The last full image, transmitted two seconds before impact, has a spatial resolution of about 3 centimeters per pixel. The impact took place on 26 September 2022, at 23:14 UTC.{{Cite web |last=Malik |first=Taliq |date=23 September 2022 |title=DART asteroid crash: What time will NASA probe hit Dimorphos on Sept. 26? |url=https://www.space.com/dart-asteroid-impact-crash-what-time |access-date=25 September 2022 |website=Space.com}}

The head-on impact of the {{convert|500|kg}}[http://dart.jhuapl.edu/The-Spacecraft/index.php DART: Home page at APL] {{Webarchive|url=https://web.archive.org/web/20180510132556/http://dart.jhuapl.edu/The-Spacecraft/index.php|date=10 May 2018}} DART Spacecraft APL 2017 DART spacecraft at {{convert|6.6|km/s}}{{Cite web |year=2021 |title=Impactor Spacecraft |url=https://dart.jhuapl.edu/Mission/Impactor-Spacecraft.php |access-date=18 February 2021 |publisher=NASA}} {{PD-notice}}; {{cite news |last1=Andone |first1=Dakin |date=25 July 2017 |title=NASA unveils plan to test asteroid defense technique |publisher=CNN |url=https://edition.cnn.com/2017/07/01/us/nasa-asteroid-defense-trnd/index.html |access-date=25 July 2017}} or {{convert|22,530|km/h}}{{cite web |title=NASA Confirms DART Mission Impact Changed Asteroid's Motion in Space |url=https://www.nasa.gov/news-release/nasa-confirms-dart-mission-impact-changed-asteroids-motion-in-space/ |publisher=NASA}} likely imparted an energy of about 11 gigajoules, the equivalent of about three tonnes of TNT,{{Cite web |last=Soldini |first=Stefania |title=Can we really deflect an asteroid by crashing into it? Nobody knows, but we are excited to try |url=http://theconversation.com/can-we-really-deflect-an-asteroid-by-crashing-into-it-nobody-knows-but-we-are-excited-to-try-190865 |access-date=23 September 2022 |website=The Conversation |date=21 September 2022 |language=en}} and was expected to reduce the orbital velocity of Dimorphos between {{val|1.75|u=cm/s}} and {{val|2.54|u=cm/s}}, depending on numerous factors such as material porosity.{{Cite web |last=Stickle |first=Angela |year=2022 |title=NASA's Double Asteroid Redirection Test Press Kit |url=https://dart.jhuapl.edu/News-and-Resources/files/DART-press-kit-web-FINAL.pdf|access-date=November 5, 2022|publisher=Johns Hopkins Applied Research Laboratory}}{{Failed verification|date=February 2025|reason=No estimate of velocity change in press kit. Actual change was 2.7 mm/s and was larger than expected, but that's 1/10th of this 2.5cm/s.}} The reduction in Dimorphos's orbital velocity brings it closer to Didymos, resulting in the moon experiencing greater gravitational acceleration and thus a shorter orbital period.{{Cite web |date=28 September 2017 |title=Course corrector |url=https://aerospaceamerica.aiaa.org/features/course-corrector/ |access-date=27 September 2022 |website=Aerospace America |language=en-US}} The orbital period reduction from the head-on impact serves to facilitate ground-based observations of Dimorphos. An impact to the asteroid's trailing side would instead increase its orbital period towards 12 hours and make it coincide with Earth's day and night cycle, which would limit any single ground-based telescope from observing all orbital phases of Dimorphos nightly.{{Cite web |last=Lakdawalla |first=Emily |author-link=Emily Lakdawalla |date=22 September 2022 |title=DART Impact on Monday! |url=https://www.patreon.com/posts/dart-impact-on-72349462 |website=Patreon}}

File:DART-impact-SAAO-Lesedi-Mookodi.gif's 1-m Lesedi telescope]]

The measured momentum enhancement factor (called beta) of DART's impact of Dimorphos was 3.6, which means that the impact transferred roughly 3.6 times greater momentum than if the asteroid had simply absorbed the spacecraft and produced no ejecta at all – indicating the ejecta contributed more to moving the asteroid than the spacecraft did. This means one could use either a smaller impactor or shorter lead times to produce a certain deflection in an asteroid than previously expected. The value of beta depends on various factors, composition, density, porosity, etc. The goal is to use these results and modeling to infer what beta could be for another asteroid by observing its surface and possibly measuring its bulk density. Scientists estimate that DART's impact displaced over {{convert|1000000|kg}} of dusty ejecta into space – enough to fill six or seven rail cars. The tail of ejecta from Dimorphos created by the DART impact is at least {{convert|30000|km|LD mi}} long with a mass of at least {{convert|1000|tonnes}}, and possibly up to 10 times that much.{{Cite web |last=Merzdorf |first=Jessica |date=2022-12-15 |title=Early Results from NASA's DART Mission |url=http://www.nasa.gov/feature/early-results-from-nasa-s-dart-mission |access-date=2022-12-16 |website=NASA}}{{cite tweet|url=https://mobile.twitter.com/jeff_foust/status/1603478050917830657|title=One other note from the briefing: the tail of ejecta from Dimorphos created by the DART impact is at least 30,000 kilometers long, says Andy Rivkin of JHUAPL, with a mass of at least 1,000 metric tons, and possibly up to 10 times that much.|number=1603478050917830657|user=jeff_foust|date=December 15, 2022}}

File:Footprint of DART spacecraft over the spot where it impacted asteroid Dimorphos.jpg

The DART impact on the center of Dimorphos decreased the orbital period, previously 11 hours and 52 minutes, by 33±1 minutes. This large change indicates the recoil from material excavated from the asteroid and ejected into space by the impact (known as ejecta) contributed significant momentum change to the asteroid, beyond that of the DART spacecraft itself. Researchers found the impact caused an instantaneous slowing in Dimorphos's speed along its orbit of about 2.7 millimeters per second — again indicating the recoil from ejecta played a major role in amplifying the momentum change directly imparted to the asteroid by the spacecraft. That momentum change was amplified by a factor of 2.2 to 4.9 (depending on the mass of Dimorphos), indicating the momentum change transferred because of ejecta production significantly exceeded the momentum change from the DART spacecraft alone.{{cite web |last1=Furfaro |first1=Emily |title=NASA's DART Data Validates Kinetic Impact as Planetary Defense Method |url=https://www.nasa.gov/feature/nasa-s-dart-data-validates-kinetic-impact-as-planetary-defense-method |website=NASA |access-date=9 March 2023 |date=28 February 2023}} {{PD-notice}} While the orbital change was small, the change is in the velocity and over the course of years will accumulate to a large change in position.{{Cite web |title=NASA Pushes Through With Asteroid Deflection Mission That Could One Day Save Earth – Inquisitr |url=https://www.inquisitr.com/4346664/nasa-dart-asteroid-deflection-mission-save-earth-goes-into-design-phase/ |access-date=27 September 2022 |website=inquisitr.com|date=5 July 2017 }} For a hypothetical Earth-threatening body, even such a tiny change could be sufficient to mitigate or prevent an impact, if applied early enough. As the diameter of Earth is around 13,000 kilometers, a hypothetical asteroid impact could be avoided with as little of a shift as half of that (6,500 kilometers). A {{val|2|u=cm/s}} velocity change accumulates to that distance in approximately 10 years.

File:Two LICIACube LUKE images showing the ejecta morphology that were used to reduce the possible axis orientation solutions.webp

By smashing into the asteroid DART made Dimorphos an active asteroid. Scientists had proposed that some active asteroids are the result of impact events, but no one had ever observed the activation of an asteroid. The DART mission activated Dimorphos under precisely known and carefully observed impact conditions, enabling the detailed study of the formation of an active asteroid for the first time.{{cite journal |last1=Li |first1=Jian-Yang |last2=Hirabayashi |first2=Masatoshi |last3=Farnham |first3=Tony L. |last4=Sunshine |first4=Jessica M. |last5=Knight |first5=Matthew M. |last6=Tancredi |first6=Gonzalo |last7=Moreno |first7=Fernando |last8=Murphy |first8=Brian |last9=Opitom |first9=Cyrielle |last10=Chesley |first10=Steve |last11=Scheeres |first11=Daniel J. |last12=Thomas |first12=Cristina A. |last13=Fahnestock |first13=Eugene G. |last14=Cheng |first14=Andrew F. |last15=Dressel |first15=Linda |last16=Ernst |first16=Carolyn M. |last17=Ferrari |first17=Fabio |last18=Fitzsimmons |first18=Alan |last19=Ieva |first19=Simone |last20=Ivanovski |first20=Stavro L. |last21=Kareta |first21=Teddy |last22=Kolokolova |first22=Ludmilla |last23=Lister |first23=Tim |last24=Raducan |first24=Sabina D. |last25=Rivkin |first25=Andrew S. |last26=Rossi |first26=Alessandro |last27=Soldini |first27=Stefania |last28=Stickle |first28=Angela M. |last29=Vick |first29=Alison |last30=Vincent |first30=Jean-Baptiste |last31=Weaver |first31=Harold A. |last32=Bagnulo |first32=Stefano |last33=Bannister |first33=Michele T. |last34=Cambioni |first34=Saverio |last35=Bagatin |first35=Adriano Campo |last36=Chabot |first36=Nancy L. |last37=Cremonese |first37=Gabriele |last38=Daly |first38=R. Terik |last39=Dotto |first39=Elisabetta |last40=Glenar |first40=David A. |last41=Granvik |first41=Mikael |last42=Hasselmann |first42=Pedro H. |last43=Herreros |first43=Isabel |last44=Jacobson |first44=Seth |last45=Jutzi |first45=Martin |last46=Kohout |first46=Tomas |last47=La Forgia |first47=Fiorangela |last48=Lazzarin |first48=Monica |last49=Lin |first49=Zhong-Yi |last50=Lolachi |first50=Ramin |last51=Lucchetti |first51=Alice |last52=Makadia |first52=Rahil |last53=Epifani |first53=Elena Mazzotta |last54=Michel |first54=Patrick |last55=Migliorini |first55=Alessandra |last56=Moskovitz |first56=Nicholas A. |last57=Ormö |first57=Jens |last58=Pajola |first58=Maurizio |last59=Sánchez |first59=Paul |last60=Schwartz |first60=Stephen R. |last61=Snodgrass |first61=Colin |last62=Steckloff |first62=Jordan |last63=Stubbs |first63=Timothy J. |last64=Trigo-Rodríguez |first64=Josep M. |title=Ejecta from the DART-produced active asteroid Dimorphos |journal=Nature |date=1 March 2023 |volume=616 |issue=7957 |pages=452–456 |doi=10.1038/s41586-023-05811-4 |pmid=36858074 |pmc=10115637 |arxiv=2303.01700 |bibcode=2023Natur.616..452L |s2cid=257282549 |language=en |issn=1476-4687 |display-authors=3}} Observations show that Dimorphos lost approximately 1 million kilograms of mass as a result of the collision.{{cite journal |last1=Witze |first1=Alexandra |title=Asteroid lost 1 million kilograms as a result of the collision with DART spacecraft |journal=Nature |date=1 March 2023 |volume=615 |issue=7951 |pages=195 |doi=10.1038/d41586-023-00601-4 |pmid=36859675 |bibcode=2023Natur.615..195W |s2cid=257282080 |url=https://www.nature.com/articles/d41586-023-00601-4 |access-date=9 March 2023 |language=en|url-access=subscription }}

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File:DART AnimatedSequence-2020 from launch to impact along with separation of LICIACube.webm|DART Mission animated video from launch to impact along with separation of LICIACube

File:Infographic of DART and Didymos Sizes.jpg|Size comparison of DART and the two Didymos asteroids

File:This chart offers insight into data the DART team used to determine the orbit of Dimorphos after impact.jpg|This chart offers insight into data the DART team used to determine the orbit of Dimorphos after impact.

File:Webb and Hubble Capture Detailed Views of DART Impact (weic2215a).jpeg|Images of the impact captured by the Hubble (left) and Webb space telescopes (right).{{cite news |url=https://esawebb.org/news/weic2215/|title=Webb and Hubble Capture Detailed Views of DART Impact. |date=October 20, 2023}}

• {{Annotated link |Asteroid impact avoidance}}
• {{Annotated link |B612 Foundation}}
• {{Annotated link |Deep Impact (spacecraft)}}
• {{Annotated link |Don Quijote (spacecraft)}}
• {{Annotated link |NEO Surveyor}}
• {{Annotated link |The Spaceguard Foundation}}

{{notelist}}

{{Reflist}}

{{commons}}

• [https://www.nasa.gov/planetarydefense/dart Double Asteroid Redirection Test (DART) Mission] – NASA's Planetary Defense page on DART
• [https://blogs.nasa.gov/dart/2021/11/23/darts-mission-to-bump-an-asteroid/ DART's Mission to Bump an Asteroid] – NASA Blog
• [https://www.youtube.com/watch?v=E0OUvEh3HWk NASA's DART Mission Launch, 24 November 2021] – Official Broadcast/Stream
• [https://www.youtube.com/watch?v=4RA8Tfa6Sck DART's Impact with Asteroid Dimorphos (Official NASA Broadcast)]

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