65803 Didymos

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65803 Didymos
SMASS = Xk[1] · X[11]
18.0[1] · 18.16[11][8][12]
18.16±0.03[13]

65803 Didymos (

potentially hazardous asteroid and near-Earth object of the Apollo group.[a] The asteroid was discovered in 1996 by the Spacewatch survey at 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
word for 'twin'.

Didymos's moon, Dimorphos, was the target of the 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

Radar images of Didymos and its satellite Dimorphos, taken by the Arecibo Observatory in 2003

Didymos was discovered on 11 April 1996 by the

lightcurve analysis, along with Arecibo radar imaging on 23 November 2003.[4]

Orbital characteristics

Didymos orbits the Sun at a distance of 1.0–2.3 AU once every 770 days (2 years and 1 month). Its orbit has an eccentricity of 0.38 and an inclination of 3° with respect to the ecliptic. The minimum distance between the orbit of Earth and the orbit of Didymos is currently 0.04 AU (6.0 million km),[1] but will change as the asteroid is 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.[1] Even the Earth approach of October 2184 is still listed with an uncertainty region of roughly ±1343 km.[14]

Physical characteristics

Dust ejecta and tail of Didymos imaged in color by the Southern Astrophysical Research Telescope two days after DART's impact
Double tail of Didymos imaged by the Hubble Space Telescope 12 days after DART's impact

In the

oblate due to its rapid rotation.[6]

Satellite

Didymos is a

provisional designation S/2003 (65803) 1 and had been informally called "Didymoon" or "Didymos B".[20][17]

Naming

This

M.P.C. 52326).[21]

The proper name for the satellite Didymos B comes from the word "Dimorphos", Greek for "having two forms".

Two boulders (saxa) have been given names of traditional drums.[24]

Named features
Name Pronunciation Feature Named after Date approved[24]
Carillon Saxum US: /ˈkærəlɒn/
UK: /kəˈrɪljən/
boulder carillon 14 Nov 2023
Gong Saxum /ˈɡɒŋ/ boulder gong 14 Nov 2023

Exploration

Telescope image of Didymos before DART's impact
Artist's impression of the DART spacecraft
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
Animation of DART's trajectory
  DART ·   65803 Didymos ·   Earth ·   Sun ·   2001 CB21 ·   3361 Orpheus
Animation of DART around Didymos - Impact on Dimorphos
  DART ·   Didymos ·   Dimorphos

In the early 2010s, Didymos's moon, Dimorphos was to be the principal target of proposed robotic mission by the

Asteroid Impact & Deflection Assessment (AIDA) mission. The ESA dropped out, and the mission did not proceed.[25][26]

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.[27][28][29] It was accompanied by the Italian Space Agency's (ASI) six-unit LICIACube flyby Cubesat that was released 15 days before impact to observe the asteroid and DART's impact.[30]

DART was the first spacecraft to intentionally target and successfully visit an asteroid known to have a

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 Eurybates's and 15094 Polymele's moons were not discovered until months before and after Lucy's launch, respectively). Didymos is the most easily reachable asteroid of its size from Earth, requiring a delta-v of only 5.1 km/s for a spacecraft to rendezvous, compared to 6.0 km/s to reach the Moon.[31]

After two weeks of analysis, NASA announced that the collision shortened Dimorphos's orbital period around Didymos by 32 minutes,[32] far more than the minimum requirement of 73 seconds and the success benchmark of 10 minutes. The measurement has an uncertainty of ±2 minutes.[33]

Dart Impact seen by LICIACube

Another mission to Didymos was approved in November 2019 for a planned launch in 2024, to arrive at Didymos in January 2027. ESA's Hera mission is planning to survey the dynamical effects of the DART impact and measure the characteristics of the crater made by DART.[34]

See also

  • 66391 Moshup – a similar near-Earth asteroid binary system
  • List of asteroids visited by spacecraft

Notes

  1. ^
    perihelion
    (q) is less than 1.017 AU (Earth aphelion), not greater.
  2. ^ Volume-equivalent spherical diameter is calculated from an ellipsoid's volume given Didymos's dimensions of 851 × 849 × 620 m,[5]: 28–29  and then solving for radius with .
  3. ecliptic coordinates, where λ is ecliptic longitude and β is ecliptic latitude.[6]: 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 complement of β.[9]
    Therefore, given β = –84°, i = 90° – (–84°) = 174° from the ecliptic.
  4. ^ Lightcurve plots of 65803 Didymos, Palmer Divide Observatory, B. D. Warner

References

  1. ^ a b c d e f g h "JPL Small-Body Database Browser: 65803 Didymos (1996 GT)" (2017-04-27 last obs.). Jet Propulsion Laboratory. Archived from the original on 22 April 2021. Retrieved 28 June 2017. Public Domain This article incorporates text from this source, which is in the public domain.
  2. ^ "didymous". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
  3. ^ .
  4. ^ a b "65803 Didymos (1996 GT)". Minor Planet Center. Archived from the original on 12 November 2020. Retrieved 12 March 2017.
  5. ^ . (This work is licensed under a CC BY 4.0 License)
  6. ^ . 134777.
  7. . 148.
  8. ^ from the original on 3 October 2022. Retrieved 12 March 2017.
  9. ^ "Coordinate transformations". Astronomy and Astrophysics. European Southern Observatory. January 1998. Archived from the original on 17 June 2021. Retrieved 17 June 2022.
  10. S2CID 250650906
    . 163.
  11. ^ a b c d "LCDB Data for (65803) Didymos". Asteroid Lightcurve Database (LCDB). Archived from the original on 1 July 2020. Retrieved 12 March 2017.
  12. from the original on 3 October 2022. Retrieved 12 March 2017.
  13. . Retrieved 12 March 2017.
  14. ^ "Horizons Batch for 2184-Oct-14 Close Approach". JPL Horizons. Archived from the original on 15 October 2022. Retrieved 14 October 2022. RNG_3sigma = uncertainty range in km. (JPL#194/Soln.date: 2022-Oct-13 generates RNG_3sigma = 1343 km)
  15. .
  16. from the original on 3 October 2022. Retrieved 12 March 2017.
  17. ^ a b c d Talbert, Tricia (23 June 2020). "NASA's First Planetary Defense Mission Target Gets a New Name". NASA. Archived from the original on 10 February 2021. Retrieved 23 June 2020. Public Domain This article incorporates text from this source, which is in the public domain.
  18. S2CID 119248574
    .
  19. ^ Johnston, Robert (20 September 2014). "(65803) Didymos". johnstonsarchive.net. Archived from the original on 23 October 2020. Retrieved 28 June 2017.
  20. ^ "Telescopes focus on target of ESA's asteroid mission Archived 18 August 2015 at the Wayback Machine" at phys.org (30 June 2015)
  21. ^ "MPC/MPO/MPS Archive". Minor Planet Center. Archived from the original on 7 January 2022. Retrieved 12 March 2017.
  22. ^ "MPEC 2020-M83 : (65803) Didymos I = Dimorphos". Minor Planet Center. International Astronomical Union. 23 June 2020. Archived from the original on 8 October 2021. Retrieved 23 June 2020.
  23. ^ "IAU Approves Name of Target of First NASA and ESA Planetary Defence Missions". International Astronomical Union. 23 June 2020. Archived from the original on 26 September 2021. Retrieved 23 June 2020.
  24. ^ a b "Nomenclature Search Results". planetarynames.wr.usgs.gov.
  25. ^ "AIDA: Asteroid Impact and Deflection Assessment mission under study at ESA and NASA" (PDF). Observatoire de la Côte d'Azur. February 2015. Archived (PDF) from the original on 14 October 2016. Retrieved 28 June 2017.
  26. ^ "Asteroid Impact & Deflection Assessment". ESA. Archived from the original on 19 March 2018. Retrieved 28 June 2017.
  27. ^ Warren, Haygen (26 September 2022). "Brace for impact: DART successfully slams into asteroid". NASASpaceFlight.com. Archived from the original on 27 September 2022. Retrieved 27 September 2022.
  28. ^ "DART Sets Sights on Asteroid Target". NASA. 7 September 2022. Archived from the original on 21 September 2022. Retrieved 20 September 2022.
  29. ^ Potter, Sean (23 November 2021). "NASA, SpaceX Launch DART: First Test Mission to Defend Planet Earth". NASA. Archived from the original on 24 November 2021. Retrieved 25 November 2021.
  30. ^ Greshko, Michael (23 November 2021). "This NASA spacecraft will smash into an asteroid—to practice saving Earth". National Geographic. Archived from the original on 23 November 2021. Retrieved 25 November 2021.
  31. ^ "Delta-v for spacecraft rendezvous with all known near-Earth asteroids". 2010. Archived from the original on 3 June 2001. Retrieved 7 October 2010.
  32. ^ "NASA says DART's asteroid impact was a huge success". The Planetary Society. Retrieved 11 October 2022.
  33. ^ "NASA Confirms DART Mission Impact Changed Asteroid's Motion in Space". NASA. 11 October 2022. Retrieved 11 October 2022.
  34. ^ Numerical modelling of the DART impact and the importance of the Hera mission.[permanent dead link] Sabina D. Raducan, Thomas M. Davison, Gareth S. Collins. PDC 2019. Washington, D.C., USA.

External links