52246 Donaldjohanson

52246 Donaldjohanson
Discovery [1]
Discovered by S. J. Bus
Discovery site Siding Spring Obs.
Discovery date 2 March 1981
Designations
MPC designation (52246) Donaldjohanson
Named after
 Donald Johanson
(paleoanthropologist)[2]
1981 EQ5 · 1998 YF26
main-belt · (inner)
Erigone [3]
Orbital characteristics [1]
Epoch 16 February 2017 (JD 2457800.5)
Uncertainty parameter 0
Observation arc 18.12 yr (6,619 days)
Aphelion 2.8269 AU
Perihelion 1.9413 AU
2.3841 AU
Eccentricity 0.1857
3.68 yr (1,345 days)
317.07°
0° 16m 3.72s / day
Inclination 4.4192°
262.85°
213.00°
Physical characteristics
Dimensions 3.895±0.013 km[4]
0.103±0.019[4]
C [3]
15.5[1]

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

    Orbit and classification

    Donaldjohanson is a carbonaceous C-type asteroid and member of the small Erigone family, which is named after its member 163 Erigone.[3] It orbits the Sun in the inner main-belt at a distance of 1.9–2.8 AU once every 3 years and 8 months (1,345 days). Its orbit has an eccentricity of 0.19 and an inclination of 4° with respect to the ecliptic.[1] 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.[2]

    Diameter and albedo

    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.[4] It has an absolute magnitude of 15.5.[1] As of 2017, Donaldjohanson's rotation period and shape remain unknown, as no rotational lightcurve has been obtained.[5]

    Naming

    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.[6] The Lucy probe is named after the "Lucy" hominid fossil, while Donaldjohanson is named for that fossil's co-discoverer, the American paleoanthropologist Donald Johanson (born 1943). The approved naming citation was published by the Minor Planet Center on 25 December 2015 (M.P.C. 97569).[2][7]

    Lucy mission target

    Donaldjohanson is planned to be visited by the Lucy spacecraft which will launch in 2021. The fly by 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][6][8]

    1. 52246 Donaldjohanson — 20 April 2025: 4 km diameter C-type asteroid in the inner main-belt, member of ~130Myr old Erigone family;
    2. 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;
    3. 15094 Polymele — 15 September 2027: 21 km diameter P-type Trojan at L4, likely collisional fragment;
    4. 11351 Leucus — 18 April 2028: 34 km diameter D-type slow rotator Trojan at L4;
    5. 21900 Orus — 11 November 2028: 51 km diameter D-type Trojan at L4;
    6. 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.

    See also

    References

    1. 1 2 3 4 5 "JPL Small-Body Database Browser: 52246 Donaldjohanson (1981 EQ5)" (2017-01-29 last obs.). Jet Propulsion Laboratory. Retrieved 5 July 2017.
    2. 1 2 3 4 "52246 Donaldjohanson (1981 EQ5)". Minor Planet Center. Retrieved 12 April 2017.
    3. 1 2 3 4 5 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. 1 2 3 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. Bibcode:2011ApJ...741...68M. arXiv:1109.4096 Freely accessible. doi:10.1088/0004-637X/741/2/68. Retrieved 12 April 2017.
    5. ↑ "LCDB Data for (52246) Donaldjohanson". Asteroid Lightcurve Database (LCDB). Retrieved 12 April 2017.
    6. 1 2 Casey Dreier; Emily Lakdawalla (30 September 2015). "NASA announces five Discovery proposals selected for further study". The Planetary Society. Retrieved 12 April 2017.
    7. ↑ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 12 April 2017.
    8. ↑ https://www.hou.usra.edu/meetings/lpsc2017/pdf/2025.pdf
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