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User:Nrco0e/Notes/Dimorphos

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Dimorphos
Dimorphos captured by the DART spacecraft, seconds before impact in September 2022
Discovery[1]
Discovered byPetr Pravec et al.[a]
Discovery siteOndřejov Observatory
Discovery date20 November 2003
Designations
Designation
Didymos I
Pronunciation/daɪˈmɔːrfəs/
Named after
Greek word for "having two forms"[2]
S/2003 (65803) 1
Didymos B
Didymoon
Orbital characteristics[3]: 17 
Pre-impact:
 1.187±0.017 km[4]
Post-impact:
 1.152±0.018 km[3]: 17 
EccentricityPre-impact:
 <0.03[3]: 17 
Post-impact:
 0.0274±0.0015[4]
Pre-impact:
 11.921493±0.000030 hr
 (11h 55m 17.4s ± 0.1s)[5]: 28 
Post-impact:
 11.3675±0.0004 hr
 (11h 22m 3.0s ± 1.4s)[5]
Pre-impact:
 0.174 m/s[b]
Post-impact:
 0.177 m/s[b]
Inclination170.7°±0.5° (to ecliptic)[c]
Satellite of65803 Didymos
Physical characteristics[7]: 12 
DimensionsPre-impact:
 179 × 169 × 115 m
 (± 1 × 4 × 1 m)[d]
Post-impact:
 192 × 148 × 118 m
 (± 12 × 8 × 14 m)[4]
Mean diameter
150.0±2.5 m (volume equivalent)
7.47×104 m2
Volume1.76×106 m3
Mass≈ 4.3×109 kg (if same density as Didymos)[8]: 9 
Mean density
<2.4±0.3 g/cm3 (assuming same as Didymos)[8]: 9 [9]
Pre-impact:
 synchronous[3]: 17 
Post-impact:
 chaotic[10]
Albedo0.15±0.02[8]: 6 
Spectral type
S[11]
21.4±0.2[1][e]

Dimorphos (formal designation (65803) Didymos I; provisional designation S/2003 (65803) 1) is a small, 150-meter (490 ft) diameter moon of the near-Earth asteroid 65803 Didymos, with which it forms a binary system. Discovered on 20 November 2003 by Petr Pravec and collaborators, Dimorphos was the target of NASA's Double Asteroid Redirection Test (DART) mission, which deliberately collided a spacecraft with the moon on 26 September 2022 to alter its orbit around Didymos. Around the same time, the Italian Space Agency's LICIACube spacecraft flew by Dimorphos to image the DART impact. The impact reduced Dimorphos's orbital period by 33 minutes and ejected over 10 million kg (22 million lb) of dusty debris into space, which produced an expanding dust plume and a 70,000-kilometer (43,000 mi)-long tail of dust swept away by solar radiation pressure.[3]: 9–10 

Before DART impacted Dimorphos, the moon had an oblate spheroid shape with a surface covered in boulders and few small craters. The surface features of Dimorphos suggest that the moon is a weakly-held rubble pile that formed less than 300,000 years ago, as a result of Didymos shedding its mass by its rapid rotation. Computer simulations and telescopic observations by researchers indicate that, as a result of Dimorphos's rubble pile structure, the DART impact globally resurfaced Dimorphos and deformed its shape into an elongated ellipsoid, rather than creating an impact crater. Simulations and observations also suggest that the DART impact caused Dimorphos's rotation to begin tumbling chaotically. The European Space Agency's Hera mission is planned to arrive at the Didymos system in 2026 to further study the effects of DART's impact on Dimorphos.

Discovery edit

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

Eclipsing binary lightcurve, radar

Name edit

Designation, name

DART and LICIACube missions edit

Main articles: Double Asteroid Redirection Test and LICIACube

Planning edit

 
Animation of DART's trajectory
  DART ·   65803 Didymos ·   Earth ·   Sun ·   2001 CB21 ·   3361 Orpheus

DART mission was selected in 2015, planetary defense goals

Impact edit

 
Gallery of the DART spacecraft's final 10 images of Dimorphos, starting from 11.5 seconds before impact

Impact ejecta edit

Dust plume edit

 
South African Astronomical Observatory timelapse of the Didymos system's expanding dust plume from the DART impact

Dust tail edit

Ejected boulders edit

 
Hubble image of the Didymos system in December 2022, showing a swarm of ejected boulders and a tail of dust being blown away by solar radiation pressure

Orbit edit

Origin edit

Surface edit

Composition edit

Geology edit

Five boulders (saxa) and six craters have been given names of traditional drums from several cultures. They are approximately 10 meters across or smaller:[12]

Named features
Name Pronunciation Feature Named after Date approved[12]
Atabaque Saxum UK: /ætəˈbæki/
US: /ɑːtəˈbɑːki/		 boulder atabaque (Brazil) 25 Jan 2023
Bodhran Saxum /ˈbɔːrɑːn/ boulder bodhrán (Ireland) 25 Jan 2023
Caccavella Saxum /kækəˈvɛlə/ boulder caccavella
a.k.a. putipù (Italy)		 25 Jan 2023
Dhol Saxum /ˈdɔːl/ boulder dhol (India) 25 Jan 2023
Pūniu Saxum /ˈpuːni.uː/ boulder pūniu a.k.a kilu (Hawaii) 25 Jan 2023
Bala Crater /ˈbælə/ crater balafon (Guinea, Senegal, Mali) 14 Nov 2023
Bongo Crater /ˈbɒŋɡoʊ/ crater bongo (Cuba) 14 Nov 2023
Marimba Crater /məˈrɪmbə/ crater marimba (Central America) 14 Nov 2023
Msondo Crater /ɛmˈsɒndoʊ/ crater msondo (Tanzania) 14 Nov 2023
Naqqara Crater /næˈkɑːrə/ crater naqqara (naker) (Mid East and India) 14 Nov 2023
Tamboril Crater /tæmbəˈrɪl/ crater tamboril (Uruguay, Candombe) 14 Nov 2023
 
 
Left: DART impact site on Dimorphos. Clockwise: Caccavella, Bodhran, and Atabaque saxum.
Right: Composite map of Dimorphos with named features as of 14 November 2023.

Shape and structure edit

 
Shape model of pre-impact Dimorphos, constructed from DART imagery

Rotation edit

Hera mission edit

Footnotes edit

  1. ^ Astronomers involved in the discovery of Dimorphos include P. Pravec, L. A. M. Benner, M. C. Nolan, P. Kusnirak, D. Pray, J. D. Giorgini, R. F. Jurgens, S.J. Ostro, J.-L. Margot, C. Magri, A. Grauer, and S. Larson. The discovery used lightcurve and radar observations from the Jet Propulsion Laboratory, Pasadena, CA; National Astronomy and Ionosphere Center / Arecibo Observatory, Arecibo, PR; and Ondrejov Observatory, Ondřejov, CZ.[1]
  2. ^ a b For a circular orbit with negligible eccentricity, the mean orbital speed can be approximated by the time T it takes to complete one revolution around its orbital circumference, with the radius being its semi-major axis a:   .
  3. ^ Naidu et al. (2024) give Didymos's rotational north pole direction in terms of ecliptic coordinates, where λ is ecliptic longitude and β is ecliptic latitude.[4] β is the angular offset from the ecliptic plane, whereas inclination or obliquity i with respect to the ecliptic is the angular offset of Didymos's rotational north pole from the ecliptic north pole, at β = +90° ; i with respect to the ecliptic would be the complement of β.[6] Therefore, given β = –80.7° , i = 90° – (–80.7°) = 170.7° from the ecliptic. Naidu et al. (2024) assume that Dimorphos's orbit is coplanar to Didymos's equator, so Dimorphos's orbital inclination would be the same as Didymos's obliquity.
  4. ^ The dimensions 179 × 169 × 115 refer to the longest extent of Dimorphos's shape. If using a triaxial ellipsoid to approximate Dimorphos's shape, then the dimensions are 173 × 170 × 113.[7]: 12 
  5. ^ Absolute magnitude of Dimorphos calculated from the addition of its magnitude difference to Didymos's absolute magnitude: 18.07 + 3.29 ≈ 21.4.[1]

References edit

  1. ^ a b c d Cite error: The named reference johnston was invoked but never defined (see the help page).
  2. ^ "IAU approves name of target of first NASA and ESA planetary defence missions". iau.org (Press release). International Astronomical Union. 23 June 2020. Retrieved 1 July 2020.
  3. ^ a b c d e Chabot, Nancy L.; Rivkin, Andrew S.; Cheng, Andrew F.; Barnouin, Olivier S.; Fahnestock, Eugene G.; Richardson, Derek C.; et al. (February 2024). "Achievement of the Planetary Defense Investigations of the Double Asteroid Redirection Test (DART) Mission". The Planetary Science Journal. 5 (2): 24. Bibcode:2024PSJ.....5...49C. doi:10.3847/PSJ/ad16e6. 49.
  4. ^ a b c d Cite error: The named reference Naidu2024 was invoked but never defined (see the help page).
  5. ^ a b Scheirich, Peter; Pravec, Petr; Meyer, Alex J.; Agrusa, Harrison F.; Richardson, Derek C.; Chesley, Steven R.; et al. (January 2024). "Dimorphos Orbit Determination from Mutual Events Photometry". The Planetary Science Journal. 5 (1): 12. Bibcode:2024PSJ.....5...17S. doi:10.3847/PSJ/ad12cf. 17.
  6. ^ "Coordinate transformations". Astronomy and Astrophysics. European Southern Observatory. January 1998. Archived from the original on 17 June 2021. Retrieved 17 June 2022.
  7. ^ a b Daly, R. Terik; Ernst, Carolyn M.; Barnouin, Olivier S.; Gaskell, Robert W.; Nair, Hari; Agrusa, Harrison; et al. (January 2024). "An Updated Shape Model of Dimorphos from DART Data". The Planetary Science Journal. 5 (1): 19. Bibcode:2024PSJ.....5...24D. doi:10.3847/PSJ/ad0b07. 24.
  8. ^ a b c Daly, R. Terik; Ernst, Carolyn M.; Barnouin, Olivier S.; Chabot, Nancy L.; Rivkin, Andrew S.; Cheng, Andrew F.; et al. (April 2023). "Successful Kinetic Impact into an Asteroid for Planetary Defense". Nature. 616 (7957): 443–447. arXiv:2303.02248. Bibcode:2023Natur.616..443D. doi:10.1038/s41586-023-05810-5. PMC 10115643. PMID 36858073.
  9. ^ Raducan, S. D.; Jutzi, M.; Cheng, A. F.; Zhang, Y.; Barnouin, O.; Collins, G. S.; et al. (February 2024). "Physical properties of asteroid Dimorphos as derived from the DART impact". Nature Astronomy: 21. doi:10.1038/s41550-024-02200-3.
  10. ^ Cite error: The named reference Agrusa2021 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Nakano2022 was invoked but never defined (see the help page).
  12. ^ a b "Planetary Names". planetarynames.wr.usgs.gov.

External links edit


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