Dimorphos

From testwiki
Revision as of 00:44, 18 December 2024 by imported>DonFB (→Exploration: Include space agency name; rmv promotional text on company; link to name of cubesat has company info)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to navigation Jump to search

Template:Short description Template:Use dmy dates Template:Infobox planet

Dimorphos (formal designation (65803) Didymos I; provisional designation S/2003 (65803) 1) is a natural satellite or moon of the near-Earth asteroid 65803 Didymos, with which it forms a binary system. The moon was discovered on 20 November 2003 by Petr Pravec in collaboration with other astronomers worldwide. Dimorphos has a diameter of Template:Convert across its longest extent and it was the target of the Double Asteroid Redirection Test (DART), a NASA space mission that deliberately collided a spacecraft with the moon on 26 September 2022 to alter its orbit around Didymos. Before the impact by DART, Dimorphos had a shape of an oblate spheroid with a surface covered in boulders but virtually no craters.[1] The moon is thought to have formed when Didymos shed its mass due to its rapid rotation, which formed an orbiting ring of debris that conglomerated into a low-density rubble pile that became Dimorphos today.[2][3][4]

The DART impact reduced Dimorphos's orbital period around Didymos by 33 minutes and ejected over Template:Convert of debris into space, producing a dust plume that temporarily brightened the Didymos system and developed a Template:Convert-long dust tail that persisted for several months.[5][6][7] The DART impact is predicted to have caused global resurfacing and deformation of Dimorphos's shape, leaving an impact crater several tens of meters in diameter.[8][9][10] Post-impact observations of brightness fluctuations within the Didymos system suggest that the impact may have either significantly deformed Dimorphos into an ellipsoidal shape or may have sent it into a chaotically tumbling rotation.[11][12] If Dimorphos was in a tumbling rotation state, the moon will be subjected to irregular tidal forces by Didymos before it will eventually return to a tidally locked state within several decades.[13][14][15] The ESA mission Hera is planned to arrive at the Didymos system in 2026 to further study the effects of DART's impact on Dimorphos.

Discovery

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

The primary asteroid Didymos was discovered in 1996 by Joe Montani of the Spacewatch Project at the University of Arizona.[16] The satellite Dimorphos was discovered on 20 November 2003, in photometric observations by Petr Pravec and colleagues at the Ondřejov Observatory in the Czech Republic. Dimorphos was detected through periodic dips in Didymos's brightness due to mutual eclipses and occultations. With his collaborators, he confirmed from the Arecibo radar delay-Doppler images that Didymos is a binary system.[17][18]

Etymology

The Working Group for Small Bodies Nomenclature of the International Astronomical Union (IAU) gave the satellite its official name on 23 June 2020.[19] The name Dimorphos is derived from a Greek word (Template:Lang) meaning 'having two forms'.[20][21]Template:Efn The justification for the new name reads: "As the target of the DART and Hera space missions, it will become the first celestial body in cosmic history whose form was substantially changed as a result of human intervention (the DART impact)".[22] The name was suggested by Kleomenis Tsiganis, a planetary scientist at the Aristotle University of Thessaloniki and a member of both the DART and Hera teams.[22] Prior to the IAU naming, the nickname Didymoon was used in official communications.[23]

Exploration

On 24 November 2021, NASA and the Applied Physics Laboratory launched an impactor spacecraft towards Dimorphos as part of their Double Asteroid Redirection Test (DART).[24][25] DART was the first experiment conducted in space to test asteroid deflection as a method of defending Earth from potentially hazardous asteroids.[26] Following a ten-month journey to the Didymos system, the impactor collided with Dimorphos on 26 September 2022 at a speed of around Template:Convert.[26][27] The collision successfully decreased Dimorphos's orbital period around Didymos by Template:Val minutes.[28][19][29][30] Fifteen days prior to its collision, the impactor released LICIACube, an Italian Space Agency CubeSat that photographed the impact and the resulting dust plume as it performed a close flyby of the Didymos system.[24][31][32][33] Spacecraft and observatories such as Hubble, James Webb, Lucy, SAAO and ATLAS also captured the dust plume trailing the Didymos system in the days following the impact.[34][35][36][7] As part of its Hera mission, ESA launched three spacecraft to the Didymos system in 2024 to reach this asteroid system in December 2026 to further study the aftermath of the impact.[29][37][38]

A trail of dust streams from Dimorphos in this Hubble Space Telescope photo taken about three months after the collision. The asteroid is surrounded by blue dots, which are boulders ranging from 1 to 6.7 metres across that were ejected by the impact.

The DART impact on the center of Dimorphos decreased the orbital period, previously 11.92 hours, 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' 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.[39] 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.[40] 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 Template:Val velocity change accumulates to that distance in approximately 10 years.

Dart Impact seen by LICIACube

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.[39][41] Observations show that Dimorphos lost approximately 1 million kilograms after the collision.[42] Impact produced a dust plume that temporarily brightened the Didymos system and developed a Template:Convert-long dust tail that persisted for several months.[5][6][7] The DART impact is predicted to have caused global resurfacing and deformation of Dimorphos's shape, leaving an impact crater several tens of meters in diameter.[8][9][10] The impact has likely sent Dimorphos into a chaotically tumbling rotation that will subject the moon to irregular tidal forces by Didymos before it will eventually return to a tidally locked state within several decades.[13][14][15] Additionally, the impact changed Dimorphos shape from a roughly symmetrical "oblate spheroid" to "a flat-topped oval", or "triaxial ellipsoid".[43][44][45]

Size and shape

Dimorphos is approximately Template:Convert in diameter, compared to Didymos at Template:Convert. Dimorphos does not have a confirmed mass, but it is estimated to be about Template:Val (5.5 million tons), or about the same mass and size as the Great Pyramid of Giza, when assuming a density of Template:Val similar to Didymos.[46] It is one of the smallest celestial objects given a formal name by the IAU, after 367943 Duende and 469219 Kamoʻoalewa.[22]

The final few minutes of pictures from the DART mission revealed an egg-shaped body covered with boulders, suggesting it has a rubble pile structure.[47][48]

Surface

Five boulders (saxa) and six craters have been given names of traditional drums from several cultures. They are approximately 10 meters across or smaller:[49]

Named features
Name Pronunciation Feature Named after Date approved[49]
Atabaque Saxum Template:IPAc-en Template:Respell
Template:IPAc-en Template:Respell		 boulder atabaque (Brazil) 25 Jan 2023
Bodhran Saxum Template:IPAc-en Template:Respell boulder bodhrán (Ireland) 25 Jan 2023
Caccavella Saxum Template:IPAc-en Template:Respell boulder caccavella
a.k.a. putipù (Italy)		 25 Jan 2023
Dhol Saxum Template:IPAc-en Template:Respell boulder dhol (India) 25 Jan 2023
Pūniu Saxum Template:IPAc-en Template:Respell boulder pūniu a.k.a. kilu (Hawaii) 25 Jan 2023
Bala Crater Template:IPAc-en Template:Respell crater balafon (Guinea, Senegal, Mali) 14 Nov 2023
Bongo Crater Template:IPAc-en Template:Respell crater bongo (Cuba) 14 Nov 2023
Marimba Crater Template:IPAc-en Template:Respell crater marimba (Central America) 14 Nov 2023
Msondo Crater Template:IPAc-en Template:Respell crater msondo (Tanzania) 14 Nov 2023
Naqqara Crater Template:IPAc-en Template:Respell crater naqqara (naker) (Mid East and India) 14 Nov 2023
Tamboril Crater Template:IPAc-en Template:Respell crater tamboril (Uruguay, Candombe) 14 Nov 2023

Template:Multiple image

Orbit and rotation

Animation of DART around Didymos - Impact on Dimorphos
Template:Legend2Template:·Template:Legend2Template:·Template:Legend2

The primary body of the binary system, Didymos, orbits the Sun at a distance of 1.0 to 2.3 AU once every 770 days (2 years and 1 month). The pathway of the orbit has an eccentricity of 0.38 and an inclination of 3° with respect to the ecliptic. On 4 October 2022 Didymos made an Earth approach of Template:Convert.[50] Dimorphos moves in a nearly equatorial, nearly circular orbit around Didymos, with an orbital period of 11.9 hours. Its orbit period is synchronous with its rotation, so that the same side of Dimorphos always faces Didymos. Dimorphos's orbit is retrograde relative to the ecliptic plane, in conformity with Didymos's retrograde rotation.[51]

Dimorphos's rotation is being slowed down by the YORP effect, with an estimated rotation period doubling time of 86,000 years. However, because it is in orbit around Didymos, tidal forces keep the moon locked in synchronous rotation.[52]

See also

  • 354P/LINEAR – a main-belt asteroid that was naturally impacted by another asteroid sometime before 2010
  • P/2016 G1 (PanSTARRS) – another main-belt asteroid that was impacted by an asteroid in 2016

Footnotes

Template:Notelist

References

Template:Reflist

Template:2022 in space Template:Solar System moons (compact)

  1. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Barnouin2023
  2. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named ESA-20210330
  3. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Zhang2021
  4. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Madeira2023
  5. ↑ 5.0 5.1 Cite error: Invalid <ref> tag; no text was provided for refs named NOIRLab-20221003
  6. ↑ 6.0 6.1 Cite error: Invalid <ref> tag; no text was provided for refs named NASA-20221215
  7. ↑ 7.0 7.1 7.2 Cite error: Invalid <ref> tag; no text was provided for refs named Li2023
  8. ↑ 8.0 8.1 Cite error: Invalid <ref> tag; no text was provided for refs named Raducan2022
  9. ↑ 9.0 9.1 Cite error: Invalid <ref> tag; no text was provided for refs named Nakano2022
  10. ↑ 10.0 10.1 Cite error: Invalid <ref> tag; no text was provided for refs named Raducan2023
  11. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Scheirich2023
  12. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Pravec2023
  13. ↑ 13.0 13.1 Cite error: Invalid <ref> tag; no text was provided for refs named Agrusa2021
  14. ↑ 14.0 14.1 Cite error: Invalid <ref> tag; no text was provided for refs named Richardson2022
  15. ↑ 15.0 15.1 Cite error: Invalid <ref> tag; no text was provided for refs named Meyer2023
  16. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named johnston
  17. ↑ Template:Cite report
  18. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Naidu2020
  19. ↑ 19.0 19.1 Template:Cite news
  20. ↑ Template:Cite web
  21. ↑ Template:LSJ
  22. ↑ 22.0 22.1 22.2 Cite error: Invalid <ref> tag; no text was provided for refs named IAU-2020-06-23
  23. ↑ Template:Cite web
  24. ↑ 24.0 24.1 Template:Cite news
  25. ↑ Template:Cite press release
  26. ↑ 26.0 26.1 Template:Cite news
  27. ↑ Template:Cite press release
  28. ↑ Template:Cite web
  29. ↑ 29.0 29.1 Template:Cite magazine
  30. ↑ Template:Cite web
  31. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Nature27Sep2022
  32. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Planetary26Sep2022
  33. ↑ Template:Cite press release
  34. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named S&T27Sep2022
  35. ↑ Template:Cite news
  36. ↑ Template:Cite web
  37. ↑ Template:Cite journal
  38. ↑ Template:Cite journal
  39. ↑ 39.0 39.1 Template:Cite web Template:PD-notice
  40. ↑ Template:Cite web
  41. ↑ Template:Cite journal
  42. ↑ Template:Cite journal
  43. ↑ Template:Cite news
  44. ↑ Template:Cite web
  45. ↑ Template:Cite journal
  46. ↑ Template:Cite journal
  47. ↑ Template:Cite web
  48. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Science27Sep2022
  49. ↑ 49.0 49.1 Template:Cite web
  50. ↑ Template:Cite report
  51. ↑ Template:Cite journal
  52. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Kanamaru2023
Retrieved from "https://en.wiki.beta.math.wmflabs.org/w/index.php?title=Dimorphos&oldid=44867"