81P / Wild 2

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81P / Wild 2 [i]
Core of comet 81P / Wild 2
Core of comet 81P / Wild 2
Properties of the orbit ( animation )
Epoch:  March 13, 2013 ( JD 2,456,364.5)
Orbit type short-term
Numerical eccentricity 0.537
Perihelion 1.60 AU
Aphelion 5.30 AU
Major semi-axis 3.45 AU
Sidereal period 6.41 a
Inclination of the orbit plane 3.2 °
Perihelion February 22, 2010
Orbital velocity in the perihelion 29.2 km / s
Physical properties of the core
Medium diameter 4 km see article text
Dimensions ~ 3 × 10 13 kg
Medium density ~ 0.5 g / cm³
Albedo 0.04
history
Explorer Paul Wild
Date of discovery January 6, 1978
Older name 1978 XI, 1984 XIV, 1990 XXVIII, 1978b, 1983s, 1989t
Source: Unless otherwise stated, the data comes from JPL Small-Body Database Browser . Please also note the note on comet articles .

81P / Wild 2 is a short- period comet named after the Swiss astronomer Paul Wild , by whom it was discovered on January 6, 1978. The comet was established in January 2004 by the NASA -Raumsonde Stardust investigated.

Orbit

It is believed that, during its 4.5 billion year existence, Wild 2 had a wider and less eccentric orbit than it does today. After it approached the planet Jupiter to around 0.006 AU in 1974 , its strong gravitational forces influenced the comet's orbit. As a result of this orbital disruption , it was redirected into the inner solar system : its orbital period was shortened from forty to about six years, and its perihelion distance was reduced from around 5 AU to only 1.60 AU. The aphelion of its orbit has since been 5.30 AU and its inclination 3.24 °.

Stardust spacecraft

Wild 2 was examined by the Stardust spacecraft on January 2, 2004 . She collected particle samples from the coma and brought them to Earth on January 15, 2006 for examination. This made it possible for the first time to examine material from a comet, which is unlikely to have changed much since the formation of the solar system , directly in laboratories . A study of cometary dust by A'Hearn, Brownlee et al., Keller et al. and Zolensky et al. and summarized by Vivien Gornitz in the "Mineral News" in January 2007 showed that the dust contains the minerals anorthite , cubanite , diopside , iron , enstatite , essenite , forsterite , gehlenite , clinoenstatite , corundum , osbornite , pentlandite , perovskite , pyrrhotite , roedderite and contains spinel .

After further investigations, microscopic traces of the amino acid glycine were also detected in 2009 . This was the first evidence of a basic building block of life in a comet and supported the panspermia hypothesis that life in the universe was the rule rather than the exception.

The 72 close-up photos taken of Stardust show a cometary nucleus around 5 km in diameter and an albedo of 0.04. Its rough surface is covered with flat hollows, the edges of which are steep and rugged. In addition to very small structures, structures up to two kilometers in size can also be recognized. It is believed that these structures represent impact craters or were formed by escaping gas jets . At least ten gas jets were active during Stardust's flyby.

See also

Individual evidence

  1. ^ Mindat - Locality report of Comet Wild 2 (Comet 81P), Solar System
  2. ↑ Sylvia Schmitz, Frank E. Brenker: Microstructural Indications for Protoenstatite Precursor of Cometary MgSiO 3 Pyroxene: A Further High-Temperature Component of Comet Wild 2 . In: The Astrophysical Journal . tape 681 , 2008, p. L105-L108 ( researchgate.net [PDF; 1.7 MB ; accessed on May 18, 2019]).
  3. ↑ Probe finds life building block in comet dust spiegel.de
  4. ↑ NASA Researchers Make First Discovery of Life's Building Block in Comet www.nasa.gov
  5. ↑ Jamie E. Elsila, et al .: Cometary glycine detected in samples returned by Stardust. In: Meteoritics & Planetary Science. Vol. 44, No. 9, 2009, pp. 1323-1330 PDF online @ gsfc.nasa.gov, accessed on November 23, 2011

Web links

Commons : Comet Wild 2  - Collection of images, videos and audio files