81P/Wild
187391
213550824
2008-05-19T20:53:24Z
Chesnok
368720
[[WP:UNDO|Undid]] revision 213340167 by [[Special:Contributions/VividSteve|VividSteve]] ([[User talk:VividSteve|talk]])
{{Infobox Comet
| name=81P/Wild
| image=[[Image:Comet_wild_2_craters.JPG|250px]]
| caption=Enhanced image from the [[Stardust (spacecraft)|Stardust]] spacecraft
| discoverer=[[Paul Wild (Swiss astronomer)|Paul Wild]]
| discovery_date=1978
| designations=1978 XI; 1984 XIV;<br/>1990 XXVIII
| epoch=[[March 6]], [[2006]]
| semimajor=3.45 [[Astronomical Unit|AU]]
| perihelion=1.592 AU
| aphelion=5.308 AU
| eccentricity=0.5384
| period=6.408 [[Julian year (astronomy)|a]]
| inclination= 3.2394°
| last_p=[[September 25]], [[2003]]
| next_p=[[2010]]
}}
Comet '''81P/Wild''', also known as '''Wild 2''', is a [[comet]] named after [[Switzerland|Swiss]] astronomer [[Paul Wild (Swiss astronomer)|Paul Wild]] (pronounced ''Vilt''), who discovered it in 1978.
It is believed that for most of its 4.5 billion-year lifetime, Wild 2 had a more distant and circular [[orbit]]. In 1974, it passed within only about one million kilometers of the planet [[Jupiter (planet)|Jupiter]], whose strong gravitational pull altered the comet's orbit and brought it into the inner [[solar system]]. Its [[orbital period]] changed from 40 years to about 6 years, and its [[perihelion]] is now about 1.59 AU ([[astronomical unit]]).<ref>{{citeweb|title=81P/Wild - Orbital Elements|url=http://cfa-www.harvard.edu/iau/Ephemerides/Comets/0081P.html|publisher=harvard.edu|accessdate=2008-03-05}}</ref>
==Stardust Mission==
NASA's [[Stardust Mission]] launched a [[spacecraft]], named [[Stardust (spacecraft)|Stardust]], on [[February 7]], [[1999]]. It flew by Wild 2 on [[January 2]], [[2004]] and collected particle samples from the comet's [[Coma (cometary)|coma]], which were returned to Earth along with [[interstellar dust]] it collected during the journey. 72 close-up shots were taken of Wild 2 by Stardust. They revealed a surface riddled with flat-bottomed depressions, with sheer walls and other features that range from very small to up to 2 [[kilometre]]s across. These features are believed to be caused by impact craters or gas vents. During Stardust's flyby, at least 10 gas vents were active. The comet itself has a diameter of 5 kilometres.
Stardust's "sample return canister," was reported to be in excellent condition when it landed in Utah, on [[January 15]], [[2006]]. A NASA team analyzed the particle capture cells and removed individual grains of comet and interstellar dust, then sent them to about 150 scientists around the globe.<ref>{{citeweb|title=Scientists Confirm Comet Samples, Briefing Set Thursday|url=http://www.nasa.gov/mission_pages/stardust/news/J06-005.html|publisher=nasa.gov|accessdate=2008-03-05}}</ref> NASA is collaborating with [[The Planetary Society]] who will run a project called "[[Stardust@Home]]," using volunteers to help locate particles on the Stardust Interstellar Dust Collector (SIDC).
So far,<ref>{{citeweb|title=
Light element isotopic compositions of cometary matter returned by the STARDUST mission|url=https://e-reports-ext.llnl.gov/pdf/339631.pdf|publisher=''[[Lawrence Livermore National Laboratory]]''|accessdate=2008-03-05}}</ref> the composition of the dust has contained a wide range of organic compounds, including two that contain biologically usable nitrogen. Indigenous aliphatic hydrocarbons were found with longer chain lengths than those observed in the diffuse interstellar medium. No hydrous silicates or carbonate minerals were detected, which suggests a lack of aqueous processing of Wild 2 dust. Very few pure carbon (CHON) particles were found in the samples returned. A substantial amount of crystalline silicates such as [[olivine]], [[anorthite]] and [[diopside]] were found,<ref>{{citeweb|title=Comet from coldest spot in solar system has material from hottest places|url=http://www.uwnews.org/article.asp?articleID=23093|publisher=uwnews.org|accessdate=2008-03-05}}</ref> materials only formed at high temperature. This is consistent with previous observations of crystalline silicates both in cometary tails and in circumstellar disks at large distances from the star. Possible explanations for this high temperature material at large distances from Sun were summarised before the Stardust sample return mission by van Boekel et al:<ref>{{citeweb|title=The building blocks of planets within the `terrestrial' region of protoplanetary disks|url=http://ukads.nottingham.ac.uk/cgi-bin/nph-bib_query?bibcode=2004Natur.432..479V&db_key=AST|publisher=ukads.nottingham.ac.uk|accessdate=2008-03-05}}</ref>
:''Both in the Solar System and in circumstellar disks crystalline silicates are found at large distances from the star. The origin of these silicates is a matter of debate. Although in the hot inner-disk regions crystalline silicates can be produced by means of gas-phase condensation or thermal annealing, the typical grain temperatures in the outer-disk (2−20 au) regions are far below the glass temperature of silicates of approx 1,000 K. The crystals in these regions may have been transported outward through the disk or in an outward-flowing wind. An alternative source of crystalline silicates in the outer disk regions is in situ annealing, for example by shocks or lightning. A third way to produce crystalline silicates is the collisional destruction of large parent bodies in which secondary processing has taken place. We can use the mineralogy of the dust to derive information about the nature of the primary and/or secondary processes the small-grain population has undergone.''
==Gallery==
<gallery>
Image:Comet_wild_2_craters.JPG|Photograph taken by Stardust spacecraft
Image:Comet_wild_2_jet_plumes.JPG|Details of the plume jets
Image:Comet Wild2 Anaglyph.jpg|Red/green stereo anaglyph
Image:Comet_Wild2_.jpg|Stardust Approach Image
Image:Comet wild 2.jpg|
</gallery>
==References==
{{reflist}}
==External links==
*[http://stardust.jpl.nasa.gov/home/index.html NASA/JPL homepage for Stardust project]
*[http://stardustathome.ssl.berkeley.edu Stardust@Home Volunteer Particle Analysis Project]
*[http://planetary.org/explore/topics/asteroids_and_comets/wild2_stardust.html Catalogue of all 72 raw images of Wild 2]
{{PeriodicComets Navigator|80P/Peters-Hartley|82P/Gehrels}}
[[Category:Comets|Wild]]
[[Category:Comets visited by spacecraft|Wild]]
[[category:Stardust (spacecraft)]]
[[de:Wild 2]]
[[et:Wild 2]]
[[es:81P/Wild]]
[[fr:81P/Wild]]
[[it:81P/Wild]]
[[ja:ヴィルト第2彗星]]
[[no:Wild 2]]
[[pl:Wild 2]]
[[pt:Wild 2]]
[[ru:Комета Вильда 2]]
[[simple:81P/Wild]]
[[sk:81P/Wild]]
[[sl:Wild 2]]
[[zh:维尔特二号]]