| Discovery[1] | |
|---|---|
| Discovered by | M. Kizawa |
| Discovery site | Shizuoka Obs. |
| Discovery date | 16 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 arc | 38.03 yr (13,890 days) |
| Aphelion | 4.4648AU |
| Perihelion | 1.1805 AU |
| 2.8226 AU | |
| Eccentricity | 0.5818 |
| 4.74yr (1,732 days) | |
| 233.20° | |
| 0° 12m 28.08s / day | |
| Inclination | 4.3056° |
| 64.643° | |
| 127.36° | |
| Earth MOID | 0.1922 AU · 74.9LD |
| Jupiter MOID | 0.5212 AU |
| Physical characteristics | |
| 2.3 km(dated)[1] 3.149 km[3] 3.15 km(taken)[4] 3.199±0.207 km[5] | |
| 3.50h[6][a] 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)[a] · 15.9±0.112[3][4] · 16.11[7] | |
(6178) 1986 DA is a metallicasteroid, classified asnear-Earth object of theAmor group, approximately 3 kilometers in diameter. It was discovered on 16 February 1986, by Japanese astronomerMinoru 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]
As an eccentric Amor asteroid has an Earthminimum 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 aMars-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 aneccentricity of 0.58 and aninclination of 4° with respect to theecliptic.[1] The firstprecovery was taken atSiding Spring Observatory in 1977, extending the asteroid'sobservation arc by 9 years prior to its discovery.[2]
The metallicM-type asteroid is notable for being significantly moreradar-reflective than otherasteroids. Radar measurements suggest it is composed ofnickel andiron and that it was derived from the center of a much larger object that experienced melting and differentiation. The observed radaralbedo was 0.58 and the optical albedo was 0.14.[8]
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.[citation needed] Severallightcurve analysis gave it a concurringrotation period of 3.50 to 3.51 hours with a relatively high brightness amplitude between 0.03 and 0.48 inmagnitude, indicating an irregular shape (U=3/3/n.a.).[6][7][a]
According to the survey carried out by NASA'sWide-field Infrared Survey Explorer with its subsequentNEOWISE 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] TheCollaborative Asteroid Lightcurve Link selects 3.15 kilometers as best result, while the first estimate from 1994 gave a diameter of 2.3 kilometers.[1]
The asteroid achieved its most notable recognition when scientists revealed that it contained over "10,000 tons of gold and 100,000 tons ofplatinum", 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 2024 the estimated value of 100,000 tons of platinum was worth approximately 3.4 trillion US dollars. Thedelta-v for a spacecraft rendezvous with this asteroid fromlow Earth orbit is 7.1 km/s.[11]
