{{Short description|Asteroid}} {{Use dmy dates|date=October 2019}} {{Infobox planet | minorplanet = yes | name = (6178) 1986 DA | background = #FFC2E0 | image = | image_size = | caption = | discovery_ref = <ref name="jpldata" /> | discovered = 16 February 1986 | discoverer = M. Kizawa | discovery_site = Shizuoka Obs. | mpc_name = (6178) 1986 DA | alt_names = | named_after = | mp_category = Amor{{·}}NEO<ref name="MPC-6178" /> | orbit_ref = <ref name="jpldata" /> | epoch = 4 September 2017 (JD 2458000.5) | uncertainty = 0 | observation_arc = 38.03 yr (13,890 days) | aphelion = 4.4648 AU | perihelion = 1.1805 AU | semimajor = 2.8226 AU | eccentricity = 0.5818 | period = 4.74 yr (1,732 days) | mean_anomaly = 233.20° | mean_motion = {{Deg2DMS|0.2078|sup=ms}} / day | inclination = 4.3056° | asc_node = 64.643° | arg_peri = 127.36° | moid = 0.1922 AU{{·}} 74.9 LD | jupiter_moid = 0.5212 AU | mean_diameter = 2.3 km {{small|(dated)}}<ref name="jpldata" /><br />{{val|3.149}} km<ref name="Pravec-2012b" /><br />3.15 km {{small|(taken)}}<ref name="lcdb" /><br />{{val|3.199|0.207}} km<ref name="WISE" /> | rotation = 3.50 h<ref name="Zeigler-1990" />{{efn|name=lcdb-Pravec}}<br />{{val|3.51}} h<ref name="Wisniewski-1987b" /> | albedo = {{val|0.0778}}<ref name="Pravec-2012b" /><br />0.15<ref name="jpldata" /><br />{{val|0.161|0.034}}<ref name="WISE" /> | spectral_type = M<ref name="lcdb" /><ref name="Ostro-1991a" /><br />B–V = 0.677<ref name="jpldata" /><br />U–B = 0.267<ref name="jpldata" /> | abs_magnitude = 15.1<ref name="jpldata" /><ref name="WISE" />{{·}}{{val|15.40|0.1}} {{small|(R)}}{{efn|name=lcdb-Pravec}}{{·}}{{val|15.9|0.112}}<ref name="Pravec-2012b" /><ref name="lcdb" />{{·}}16.11<ref name="Wisniewski-1987b" /> }}
'''{{mp|(6178) 1986 DA}}''' is a metallic asteroid, classified as a 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.<ref name="MPC-6178" />
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.<ref>{{Cite web|url=https://www.jpl.nasa.gov/news/news.php?feature=5670|title=Near-Earth Metal Asteroid Discovered|website=NASA/JPL|access-date=2018-10-30}}</ref>
== Orbit and classification ==
As an eccentric Amor asteroid has an Earth minimum orbit intersection distance of {{convert|0.1922|AU|km|abbr=on|sigfig=3}} 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.<ref name="jpldata" /> 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.<ref name="jpldata" /> The first precovery was taken at Siding Spring Observatory in 1977, extending the asteroid's observation arc by 9 years prior to its discovery.<ref name="MPC-6178" />
== 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.<ref name="Ostro-1991a" />
=== 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.{{citation needed|date=February 2016}} 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 ({{small|U=3/3/n.a.}}).<ref name="Zeigler-1990" /><ref name="Wisniewski-1987b" />{{efn|name=lcdb-Pravec}}
=== 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.<ref name="Pravec-2012b" /><ref name="WISE" /> 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.<ref name="jpldata" />
=== 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."<ref name="Ostro-1991b" /> In 2024 the estimated value of 100,000 tons of platinum was worth approximately 3.4 trillion US dollars. The delta-v for a spacecraft rendezvous with this asteroid from low Earth orbit is 7.1 km/s.<ref name="jpl-delta-v" />
== Notes == {{notelist|refs=
{{efn|name=lcdb-Pravec|1=Pravec (1999) web: rotation period {{val|3.50}} hours with a brightness amplitude of {{val|0.3}} mag. H = 15.4. No LCDB quality code assigned. No lightcurve published (note: "N"). Summary figures at [http://www.minorplanet.info/PHP/generateOneAsteroidInfo.php?AstInfo=6178%7C Collaborative Asteroid Lightcurve Link (CALL) for (6178)] and [http://www.asu.cas.cz/~ppravec/neo.htm Pravec, P.; Wolf, M.; Sarounova, L. (1999)]}}
}} <!-- end of notelist -->
== See also == * Psyche (spacecraft), planned mission to heaviest metal asteroid 16 Psyche
== References == <references>
<ref name="jpldata">{{cite web |type = 2015-07-28 last obs. |title = JPL Small-Body Database Browser: 6178 (1986 DA) |url = https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2006178 |publisher = Jet Propulsion Laboratory |accessdate = 26 May 2017}}</ref>
<ref name="MPC-6178">{{cite web |title = 6178 (1986 DA) |work = Minor Planet Center |url = https://www.minorplanetcenter.net/db_search/show_object?object_id=6178 |accessdate = 26 May 2016}}</ref>
<ref name="Ostro-1991a">{{cite journal |first1 = S. J. |last1 = Ostro |first2 = K. D. |last2 = Rosema |first3 = D. B. |last3 = Campbell |first4 = J. F. |last4 = Chandler |first5 = A. A. |last5 = Hine |first6 = R. S. |last6 = Hudson |date = June 1991 |title = Asteroid 1986 DA - Radar evidence for a metallic composition |journal = Science |pages = 1399–1404 |issn = 0036-8075 |bibcode = 1991Sci...252.1399O |doi = 10.1126/science.252.5011.1399 |pmid = 17772910 |volume = 252 |issue = 5011 |hdl = 2060/19920003664|s2cid = 2510757 |hdl-access= free }}</ref>
<ref name="Ostro-1991b">{{cite journal |display-authors = 6 |first1 = Steven J. |last1 = Ostro |first2 = D. B. |last2 = Campbell |first3 = J. F. |last3 = Chandler |first4 = A. A. |last4 = Hine |first5 = R. S. |last5 = Hudson |first6 = K. D. |last6 = Rosema |first7 = Irwin I. |last7 = Shapiro |date = October 1991 |title = Asteroid 1986 DA: Radar evidence for a metallic composition |journal = Science |volume = 252 |issue = 5011 |pages = 1399–1704 |doi = 10.1126/science.252.5011.1399 |pmid = 17772910 |bibcode = 1991plas.rept..174O|hdl= 2060/19920003664 |s2cid = 2510757 |hdl-access= free }}</ref>
<ref name="jpl-delta-v">{{cite web |title = Delta-v for spacecraft rendezvous with all known near-Earth asteroids |publisher = NASA |date = 2006-06-01 |url = http://echo.jpl.nasa.gov/~lance/delta_v/delta_v.rendezvous.html |archive-url = https://web.archive.org/web/20010603042837/http://echo.jpl.nasa.gov/~lance/delta_v/delta_v.rendezvous.html |url-status = dead |archive-date = 2001-06-03 |accessdate = 8 June 2006}}</ref>
<ref name="lcdb">{{cite LCDB|number = 6178 |accessdate = 26 May 2016}}</ref>
<ref name="Pravec-2012b">{{Cite journal |first1 = Petr |last1 = Pravec |first2 = Alan W. |last2 = Harris |first3 = Peter |last3 = Kusnirák |first4 = Adrián |last4 = Galád |first5 = Kamil |last5 = Hornoch |date = September 2012 |title = Absolute magnitudes of asteroids and a revision of asteroid albedo estimates from WISE thermal observations |journal = Icarus |volume = 221 |issue = 1 |pages = 365–387 |bibcode = 2012Icar..221..365P |doi = 10.1016/j.icarus.2012.07.026|hdl= 11104/0217021 |hdl-access= free }}</ref>
<ref name="WISE">{{cite journal |display-authors = 6 |first1 = A. |last1 = Mainzer |first2 = T. |last2 = Grav |first3 = J. |last3 = Masiero |first4 = E. |last4 = Hand |first5 = J. |last5 = Bauer |first6 = D. |last6 = Tholen |first7 = R. S. |last7 = McMillan |first8 = T. |last8 = Spahr |first9 = R. M. |last9 = Cutri |first10 = E. |last10 = Wright |first11 = J. |last11 = Watkins |first12 = W. |last12 = Mo |first13 = C. |last13 = Maleszewski |date = November 2011 |title = NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results |journal = The Astrophysical Journal |volume = 741 |issue = 2 |page = 25 |bibcode = 2011ApJ...741...90M |doi = 10.1088/0004-637X/741/2/90 |arxiv = 1109.6407|s2cid = 118700974 }}</ref>
<ref name="Wisniewski-1987b">{{Cite journal |author = Wisniewski, W. Z. |date = June 1987 |title = Photometry of six radar target asteroids |journal = Icarus |pages = 566–572 |issn = 0019-1035 |bibcode = 1987Icar...70..566W |doi = 10.1016/0019-1035(87)90096-0 |volume =70 |issue = 3}}</ref>
<ref name="Zeigler-1990">{{Cite journal |author = Zeigler, K. W. |date = March 1990 |title = Photoelectric Photometry of Asteroids 81 Terpsichore, 381 Myrrha, and 1986 DA |journal = The Minor Planet Bulletin |volume = 17 |page = 1 |bibcode = 1990MPBu...17....1Z}}</ref>
</references> <!-- end of reflist -->
== External links == * [http://www.minorplanet.info/PHP/lcdbsummaryquery.php Asteroid Lightcurve Database (LCDB)], query form ([http://www.minorplanet.info/lightcurvedatabase.html info] {{Webarchive|url=https://web.archive.org/web/20171216050541/http://www.minorplanet.info/lightcurvedatabase.html |date=16 December 2017 }}) * [https://books.google.com/books?id=aeAg1X7afOoC&pg Dictionary of Minor Planet Names], Google books * [http://obswww.unige.ch/~behrend/page_cou.html Asteroids and comets rotation curves, CdR] – Observatoire de Genève, Raoul Behrend * {{NeoDys|6178}} * {{ESA-SSA|6178|1986DA}} * {{JPL small body}}
{{Minor planets navigator |(6177) 1986 CE2 |number=6178 |6179 Brett}} {{Small Solar System bodies}} {{Authority control}}
{{DEFAULTSORT:1986 DA}} 006178 006178 Discoveries by Minoru Kizawa 19860216