(6178) 1986 DA
Discovery[1]
Discovered byM. Kizawa
Discovery siteShizuoka Obs.
Discovery date16 February 1986
Designations
(6178) 1986 DA
1986 DA
Amor · NEO[2]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc38.03 yr (13,890 days)
Aphelion4.4648 AU
Perihelion1.1805 AU
2.8226 AU
Eccentricity0.5818
4.74 yr (1,732 days)
233.20°
0° 12m 28.08s / day
Inclination4.3056°
64.643°
127.36°
Earth MOID0.1922 AU · 74.9 LD
Jupiter MOID0.5212 AU
Physical characteristics
Mean diameter
2.3 km (dated)[1]
3.149 km[3]
3.15 km (taken)[4]
3.199±0.207 km[5]
3.50 h[6][lower-alpha 1]
3.51 h[7]
0.0778[3]
0.15[1]
0.161±0.034[5]
M[4][8]
B–V = 0.677[1]
U–B = 0.267[1]
15.1[1][5] · 15.40±0.1 (R)[lower-alpha 1] · 15.9±0.112[3][4] · 16.11[7]

    (6178) 1986 DA is a metallic asteroid, classified as near-Earth object of the Amor group, approximately 3 kilometers in diameter. It was discovered on 16 February 1986, by Japanese astronomer Minoru Kizawa at Shizuoka Observatory, Japan.[2]

    1986 DA was the first near Earth asteroid thought to be of metallic composition, with high radar brightness; with that it was predicted to have 100 thousand tons of platinum group metals including gold and suggested as a resource for future space colonists.[9]

    Orbit and classification

    As an eccentric Amor asteroid has an Earth minimum orbit intersection distance of 0.1922 AU (28,800,000 km) and approaches the orbit of Earth from the outside but does not cross it. It crosses however the orbit of Mars and can be classified as a Mars-crosser and also approaches the orbit of Jupiter within 0.5 AU.[1] The asteroid orbits the Sun at a distance of 1.2–4.5 AU once every 4 years and 9 months (1,732 days). Its orbit has an eccentricity of 0.58 and an inclination of 4° with respect to the ecliptic.[1] The first precovery was taken at Siding Spring Observatory in 1977, extending the asteroid's observation arc by 9 years prior to its discovery.[2]

    Physical characteristics

    The metallic M-type asteroid is notable for being significantly more radar-reflective than other asteroids. Radar measurements suggest it is composed of nickel and iron and that it was derived from the center of a much larger object that experienced melting and differentiation. The observed radar albedo was 0.58 and the optical albedo was 0.14.[8]

    Rotation and shape

    It was most probably formed from a larger body through a catastrophic collision with another object. Radar measurements of this body indicate that the surface is relatively smooth on scales of less than a meter, but it is highly irregular on scales of 10–100 meters. Several lightcurve analysis gave it a concurring rotation period of 3.50 to 3.51 hours with a relatively high brightness amplitude between 0.03 and 0.48 in magnitude, indicating an irregular shape (U=3/3/n.a.).[6][7][lower-alpha 1]

    Diameter and albedo

    According to the survey carried out by NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, the asteroid has an albedo of 0.08 and 0.16, and a diameter of 3.1 to 3.2 kilometers, respectively.[3][5] The Collaborative Asteroid Lightcurve Link selects 3.15 kilometers as best result, while the first estimate from 1994 gave a diameter of 2.3 kilometers.[1]

    Mining considerations

    The asteroid achieved its most notable recognition when scientists revealed that it contained over "10,000 tons of gold and 100,000 tons of platinum", or an approximate value at the time of its discovery of "$90 billion for the gold and a cool trillion dollars for the platinum, plus loose change for the asteroid's 10 billion tons of iron and a billion tons of nickel."[10] In 2012 the estimated value of 100,000 tons of platinum was worth approximately five trillion US dollars. The delta-v for a spacecraft rendezvous with this asteroid from low Earth orbit is 7.1 km/s.[11]

    Notes

    1. 1 2 3 Pravec (1999) web: rotation period 3.50 hours with a brightness amplitude of 0.3 mag. H = 15.4. No LCDB quality code assigned. No lightcurve published (note: "N"). Summary figures at Collaborative Asteroid Lightcurve Link (CALL) for (6178) and Pravec, P.; Wolf, M.; Sarounova, L. (1999)

    See also

    References

    1. 1 2 3 4 5 6 7 8 9 10 "JPL Small-Body Database Browser: 6178 (1986 DA)" (2015-07-28 last obs.). Jet Propulsion Laboratory. Retrieved 26 May 2017.
    2. 1 2 3 "6178 (1986 DA)". Minor Planet Center. Retrieved 26 May 2016.
    3. 1 2 3 4 Pravec, Petr; Harris, Alan W.; Kusnirák, Peter; Galád, Adrián; Hornoch, Kamil (September 2012). "Absolute magnitudes of asteroids and a revision of asteroid albedo estimates from WISE thermal observations". Icarus. 221 (1): 365–387. Bibcode:2012Icar..221..365P. doi:10.1016/j.icarus.2012.07.026.
    4. 1 2 3 "LCDB Data for (6178)". Asteroid Lightcurve Database (LCDB). Retrieved 26 May 2016.
    5. 1 2 3 4 Mainzer, A.; Grav, T.; Masiero, J.; Hand, E.; Bauer, J.; Tholen, D.; et al. (November 2011). "NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results". The Astrophysical Journal. 741 (2): 25. arXiv:1109.6407. Bibcode:2011ApJ...741...90M. doi:10.1088/0004-637X/741/2/90. S2CID 118700974.
    6. 1 2 Zeigler, K. W. (March 1990). "Photoelectric Photometry of Asteroids 81 Terpsichore, 381 Myrrha, and 1986 DA". The Minor Planet Bulletin. 17: 1. Bibcode:1990MPBu...17....1Z.
    7. 1 2 3 Wisniewski, W. Z. (June 1987). "Photometry of six radar target asteroids". Icarus. 70 (3): 566–572. Bibcode:1987Icar...70..566W. doi:10.1016/0019-1035(87)90096-0. ISSN 0019-1035.
    8. 1 2 Ostro, S. J.; Rosema, K. D.; Campbell, D. B.; Chandler, J. F.; Hine, A. A.; Hudson, R. S. (June 1991). "Asteroid 1986 DA - Radar evidence for a metallic composition". Science. 252 (5011): 1399–1404.NASA–supportedresearch.(SciHomepage). Bibcode:1991Sci...252.1399O. doi:10.1126/science.252.5011.1399. hdl:2060/19920003664. ISSN 0036-8075. PMID 17772910. S2CID 2510757.
    9. ↑ "Near-Earth Metal Asteroid Discovered". NASA/JPL. Retrieved 30 October 2018.
    10. ↑ Ostro, Steven J.; Campbell, D. B.; Chandler, J. F.; Hine, A. A.; Hudson, R. S.; Rosema, K. D.; et al. (October 1991). "Asteroid 1986 DA: Radar evidence for a metallic composition". In NASA. 252 (5011): 1399–1704. Bibcode:1991plas.rept..174O. doi:10.1126/science.252.5011.1399. hdl:2060/19920003664. PMID 17772910. S2CID 2510757.
    11. ↑ "Delta-v for spacecraft rendezvous with all known near-Earth asteroids". NASA. 1 June 2006. Archived from the original on 3 June 2001. Retrieved 8 June 2006.
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