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Double Asteroid Redirection Test (DART) is a planned space probe that will demonstrate the kinetic effects of crashing an impactor spacecraft into an asteroid moon for planetary defense purposes. The mission is intended to test whether a spacecraft impact could successfully deflect an asteroid on a collision course with Earth.

Double Asteroid Redirection Test (DART)
DART image.jpg
DART mission in space.
Mission typeAsteroid impactor
OperatorNASA / APL
Websitenasa.gov/planetarydefense/dart
dart.jhuapl.edu
Spacecraft properties
ManufacturerApplied Physics Laboratory
Launch mass500 kg (1,100 lb)
Dimensions12.5 m × 2.4 m (41.0 ft × 7.9 ft)
Start of mission
Launch dateJune 2021 (June 2021)[1]
RocketFalcon 9 [1]
Launch siteVandenberg AFB SLC-4E
ContractorSpaceX [1]
(65803) Didymos[2] impactor
Spacecraft componentDART
Impact dateOctober 2022
 

A demonstration of an asteroid deflection is a key test that NASA and other agencies wish to perform before the actual need of planetary protection is present. DART is a joint project between NASA and the Johns Hopkins Applied Physics Laboratory (APL), and it is being developed under the auspices of NASA's Planetary Defense Coordination Office.

In August 2018, NASA approved the project to start the final design and assembly phase.

Contents

HistoryEdit

Originally, the European Space Agency (ESA) and NASA had independent plans for a mission to test asteroid deflection strategies, and by 2015 they struck a collaboration called AIDA —now cancelled— that would have had the two spacecraft launch separately but work in synergy.[3][4][5] Under the proposal, the European spacecraft, AIM, would have launched in December 2020, and DART in July 2021. AIM would have orbited the larger asteroid and study its composition and that of its moon. DART would then impact the moon on October 2022, during a close approach to Earth.[4] AIM would have studied the asteroid's strength, surface physical properties and its internal structure, as well as measure the effect on the asteroid moon's orbit around the larger asteroid. Since the AIM orbiter was cancelled, the full characterization of the asteroids will not be obtained, and the effects of the impact by DART will be monitored from ground-based telescopes and radar.[6][5]

The spacecraft's solar arrays use a roll-up design called ROSA, and this was tested on the International Space Station in June 2017 as part of Expedition 52, delivered to the station by the CRS-11 commercial cargo mission.[7] In June 2017 NASA approved a move from concept development to the preliminary design phase,[8] and in August 2018 NASA approved the project to start the final design and assembly phase.[9]

On 11 April 2019, NASA announced that a SpaceX Falcon 9 would be used to launch DART.[10]

MissionEdit

 
NASA's Evolutionary Xenon Thruster (NEXT) operating in a vacuum chamber

Scientists estimate 25,000 large asteroids lurk in the Solar System, though to date, surveys have detected about 8,000, therefore NASA officials think it is imperative to develop an effective plan should a near-Earth object threaten Earth.[11] DART is an impactor that hosts no scientific payload other than a Sun sensor, a star tracker, and 20 cm aperture camera to support autonomous navigation to impact the small asteroid's moon at its center. It is estimated that the impact of the 500 kg (1,100 lb)[12] DART at 6 km/s (3.7 mi/s)[2] will produce a velocity change on the order of 0.4 mm/s, which leads to a small change in trajectory of the asteroid system, but over time, it leads to a large shift of path.[13][4][14] Overall, DART is expected to alter the speed of Didymos's orbit by about half a millimeter per second, resulting in an orbital period change of perhaps 10 minutes.[15] Over a span of millions of kilometers, the cumulative trajectory change would turn a collision with a genuinely Earth-bound asteroid or comet into a safe outcome.[16] The actual velocity change and orbital shift will be measured a few years later by a small spacecraft called Hera that would do a detailed reconnaissance and assessment.[17]

DART spacecraft will use the NEXT ion thuster, a type of solar electric propulsion.[6][18] The DART impactor is also proposed to make a flyby observation of asteroid 3361 Orpheus during its trajectory to 65803 Didymos.[19] It will obtain some images in the visible spectrum.

It was originally planned for DART to be a secondary payload on a commercial launch to keep costs low, however a mission update presentation in November 2018 notes that the mission now has a dedicated launch vehicle.[20] In April 2019 that launch vehicle was revealed to be a SpaceX Falcon 9.[10]

Secondary spacecraftEdit

The Italian Space Agency (ASI) proposes to include a secondary spacecraft called LICIA (Light Italian CubeSat for Imaging of Asteroids), a small CubeSat that would piggyback with DART and would separate shortly before impact to acquire images of the impact and ejecta as it drifts past the asteroid.[17][21] LICIA will be able to communicate directly with Earth, sending back images of the ejecta after the Didymos flyby.[22] It will have a design similar to ASI's ArgoMoon CubeSat, planned to be launched in 2020.[22]

In a separate project, the European Space Agency is formulating Hera, a spacecraft that would be launched to Didymos a few years after DART's impact to do a detailed reconnaissance and assessment.[23]

Target asteroidEdit

The mission's target is 65803 Didymos, a binary asteroid system in which one asteroid is orbited by a smaller one. The primary asteroid is about 800 m (2,600 ft) in diameter; its small satellite is about 150 m (490 ft) in diameter in an orbit about 1.1 km from the primary.[6] DART will target the smaller asteroid. Didymos is not an Earth-crossing asteroid, and there is no possibility that the deflection experiment could create an impact hazard.[14]

Similar Attempts on AsteroidsEdit

In 2018 Russian Scientists Tested their Asteroid-Nuking Plan with Powerful Lasers [24]

See alsoEdit

ReferencesEdit

  1. ^ a b c C19-009. "NASA Awards Launch Services Contract for Asteroid Redirect Test Mission". NASA. NASA. Retrieved 12 April 2019.
  2. ^ a b Andone, Dakin (July 25, 2017). "NASA unveils plan to test asteroid defense technique". CNN. Retrieved July 25, 2017.
  3. ^ AIDA DART. Home page at APL.
  4. ^ a b c Asteroid Impact & Deflection Assessment (AIDA) study Archived 2015-06-07 at the Wayback Machine.
  5. ^ a b DART, at Applied Physics Laboratory. Johns Hopkins University.
  6. ^ a b c Planetary Defense: Double Asteroid Redirection Test (DART) Mission. NASA. 2017.
  7. ^ Talbert, Tricia (2017-06-30). "Double Asteroid Redirection Test (DART) Mission". NASA. Retrieved 2018-01-21.
  8. ^ NASA plans to test asteroid deflection technique designed to prevent Earth impact G Brown. 4 July 2017
  9. ^ Asteroid-deflection mission passes key development milestone. 7 September 2018.
  10. ^ a b Northon, Karen (2019-04-11). "NASA Awards Launch Services Contract for Asteroid Redirect Test". NASA. Retrieved 2019-04-12.
  11. ^ NASA is planning an asteroid deflection test mission in case the unthinkable happens. Science Alert. 5 July 2017.
  12. ^ DART: Home page at APL. DART Spacecraft. APL, 2017.
  13. ^ Cheng, A.F.; Michel, P.; Reed, C.; Galvez, A.; Carnelli, I. (2012). DART: Double Asteroid Redirection Test (PDF). European Planetary Science Congress 2012. EPSC Abstracts.
  14. ^ a b "AIDA: Asteroid Impact and Deflection Assessment Mission Under Study at ESA and NASA" (PDF). Observatoire de la Côte d'Azur. February 2015. Retrieved 2015-03-29.
  15. ^ Course corrector. Adam Hadhazy, Aerospace America. October 2017.
  16. ^ NASA Pushes Through With Asteroid Deflection Mission That Could One Day Save Earth. The Inquisitr. 5 July 2017.
  17. ^ a b Asteroids have been hitting the Earth for billions of years. In 2022, we hit back. Andy Rivkin, The Johns Hopkins University Applied Physics Laboratory. September 27, 2018.
  18. ^ The Double Asteroid Redirection Test (DART) mission electric propulsion trade. Aerospace Conference, 2017 IEEE. Conference: 4–11 March 2017. doi:10.1109/AERO.2017.7943736
  19. ^ A.F. Cheng et al., "Asteroid Impact & Deflection Assessment mission: Kinetic impactor," Planetary and Space Science (Available online 4 January 2016)
  20. ^ Cheng, Andy (2018-11-15). "DART Mission Update" (PDF). cosmos.esa.int.
  21. ^ Kretschmar, Peter; Küppers, Michael (20 December 2018). "The CubeSat Revolution" (PDF). ESA. Retrieved 2019-01-24.
  22. ^ a b Cheng, Andy (15 November 2018). "DART Mission Update" (PDF). NASA. Retrieved 2019-01-14.
  23. ^ Bergin, Chris (January 7, 2019). "Hera adds objectives to planetary defense test mission". NASASpaceFlight.com. Retrieved 2019-01-11.
  24. ^ {{cite web |url=https://www.livescience.com/62057-asteroid-nuclear-bomb-russia-laser.html |title= Russian Scientists Tested Their Asteroid-Nuking Plan with Powerful Lasers |date=March 2018