52246 Donaldjohanson

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52246 Donaldjohanson
Discovery [1]
Discovered byS. J. Bus
Discovery siteSiding Spring Obs.
Discovery date2 March 1981
MPC designation(52246) Donaldjohanson
Named after
Donald Johanson[1]
1981 EQ5 · 1998 YF26
main-belt[1][2] · (inner)
Orbital characteristics[2]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc18.12 yr (6,619 d)
Aphelion2.8274 AU
Perihelion1.9415 AU
2.3844 AU
3.68 yr (1,345 d)
0° 16m 3.72s / day
Physical characteristics
Mean diameter
3.895±0.013 km[5]

52246 Donaldjohanson, provisional designation 1981 EQ5, is a carbonaceous Erigonian asteroid from the inner regions of the asteroid belt, approximately 4 kilometers (2.5 miles) in diameter. It was discovered on 2 March 1981, by American astronomer Schelte Bus at the Siding Spring Observatory in Australia. The C-type asteroid is a target of the Lucy mission and was aptly named after American paleoanthropologist Donald Johanson.[1]

Orbit and classification[edit]

Donaldjohanson is a member of the Erigone family (406),[3][4] a large carbonaceous asteroid family of nearly 2,000 known members, which is named after its parent body 163 Erigone. It is a relatively old family that was created approximately 130 million years ago.[6]

It orbits the Sun in the inner asteroid belt at a distance of 1.9–2.8 AU once every 3 years and 8 months (1,345 days; semi-major axis of 2.38 AU). Its orbit has an eccentricity of 0.19 and an inclination of 4° with respect to the ecliptic.[2] A first precovery was taken at the discovering observatory in February 1981, extending the body's observation arc by 2 weeks prior to its official discovery observation.[1]

Lucy mission target[edit]

Donaldjohanson is planned to be visited by the Lucy spacecraft which will launch in 2021. The flyby is scheduled for 20 April 2025, and will approach the asteroid to a distance of 922 kilometers at a velocity of 13.4 kilometers per second.[3] The mission's targets with their flyby dates are:[3][7][8]

  • 52246 Donaldjohanson — 20 April 2025: 4 km diameter C-type asteroid in the inner main-belt, member of the Erigone family;
  • 3548 Eurybates — 12 August 2027: 64 km diameter C-type Jupiter Trojan in the Greek camp at L4, largest member of the only confirmed disruptive collisional family in the Trojans;
  • 15094 Polymele — 15 September 2027: 21 km diameter P-type Trojan at L4, likely collisional fragment;
  • 11351 Leucus — 18 April 2028: 34 km diameter D-type slow rotator Trojan at L4;
  • 21900 Orus — 11 November 2028: 51 km diameter D-type Trojan at L4;
  • 617 Patroclus — 2 March 2033: P-type binary Trojan. The primary, Patroclus, has a mean diameter of 113 km and its companion, Menoetius, has a diameter of 104 km. The pair orbit at a separation of 680 km. The binary resides in the Trojan camp at L5.

Physical characteristics[edit]

Donaldjohanson has been characterized as a carbonaceous C-type asteroid,[3] in-line with the C and X overall spectral type for Erigonian asteroids.[6]:23 It has an absolute magnitude of 15.5.[2] As of 2018, the asteroid's period, pole and shape remain unknown.[2][9]

Diameter and albedo[edit]

According to the survey carried out by NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Donaldjohanson measures 3.895 kilometers in diameter and its surface has an albedo of 0.103.[5]


This minor planet is planned to be visited by the Lucy spacecraft, which would observe it en route to its main target of several Jupiter trojans.[7] The Lucy probe is named after the "Lucy" hominid fossil, while Donaldjohanson is named for that fossil's co-discoverer Donald Johanson (born 1943), an American paleoanthropologist. The approved naming citation was published by the Minor Planet Center on 25 December 2015 (M.P.C. 97569).[1][10]

See also[edit]


  1. ^ a b c d e f "52246 Donaldjohanson (1981 EQ5)". Minor Planet Center. Retrieved 28 April 2018.
  2. ^ a b c d e f "JPL Small-Body Database Browser: 52246 Donaldjohanson (1981 EQ5)" (2017-01-29 last obs.). Jet Propulsion Laboratory. Retrieved 28 April 2018.
  3. ^ a b c d e f Levison, H. F.; Olkin, C.; Noll, K. S.; Marchi, S.; Lucy Team (March 2017). "Lucy: Surveying the Diversity of the Trojan Asteroids: The Fossils of Planet Formation" (PDF). 48th Lunar and Planetary Science Conference. Bibcode:2017LPI....48.2025L. Retrieved 13 April 2017.
  4. ^ a b "Small Bodies Data Ferret". Nesvorny HCM Asteroid Families V3.0. Retrieved 1 September 2017.
  5. ^ a b c Masiero, Joseph R.; Mainzer, A. K.; Grav, T.; Bauer, J. M.; Cutri, R. M.; Dailey, J.; et al. (November 2011). "Main Belt Asteroids with WISE/NEOWISE. I. Preliminary Albedos and Diameters". The Astrophysical Journal. 741 (2): 20. arXiv:1109.4096. Bibcode:2011ApJ...741...68M. doi:10.1088/0004-637X/741/2/68. Retrieved 12 April 2017.
  6. ^ a b Nesvorný, D.; Broz, M.; Carruba, V. (December 2014). "Identification and Dynamical Properties of Asteroid Families" (PDF). Asteroids IV: 297–321. arXiv:1502.01628. Bibcode:2015aste.book..297N. doi:10.2458/azu_uapress_9780816532131-ch016. Retrieved 28 April 2018.
  7. ^ a b Casey Dreier; Emily Lakdawalla (30 September 2015). "NASA announces five Discovery proposals selected for further study". The Planetary Society. Retrieved 12 April 2017.
  8. ^ https://www.hou.usra.edu/meetings/lpsc2017/pdf/2025.pdf
  9. ^ "LCDB Data for (52246) Donaldjohanson". Asteroid Lightcurve Database (LCDB). Retrieved 12 April 2017.
  10. ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 28 April 2018.

External links[edit]