Archive of Astronomy Questions and Answers

Can you say anything about comet P/Wild 2?

In early January of 1978, astronomer Paul Wild at the Astronomical Institute of Berne University examined photographic plates taken on January 6 and 8 1978, and with the 40-centimeter Schmidt camera. He discovered this comet with a magnitude of +13.5 - +14 and reported it to the Brian Marsden at Harvard Observatory. Its discovery appeared in IAU Circular No. 3166. In the next circular, Brian Marsden used the observations to compute an orbit for this new comet ( about a dozen new comets are discovered every year!) and got the following solution:


T = 1978 June 14

w = 39.48 degrees

W = 136.33 degrees

i = 3.26

q = 1.4891 AU

e = 0.5566

a = 3.3583 AU

n0 =0.16015

P = 6.15 years

The comet, designated as 1978 XI or P/Wild 2, has a period of 6.15 years which makes it a new short-period comet, with a perihelion distance of 1.4891 AU, which means it never gets inside the orbit of the Earth.

In 1983, it was reacquired as Comet 1983 XIV or 1983s at virtually the same location as predicted for it by the initial orbit solution. It is however a faint comet, rarely exceeding a brightness of +9.0 making it undetectable except with a telescope. Evidently, Wild 2 is one of only 10 known comets that has been significantly perturbed by Jupiter. It experienced a close encounter with Jupiter in 1974 at a distance of only 560,000 miles which evidently put it in its present orbit. Prior to that, the comet probably never got much inside the orbit of Mars and would have escaped detection.

Out of some 130 known short-period comets, Wild 2 and Kopff were considered as prime targets for a flyby mission in May 1997 by mission planners in the 1980's. In fact, Wild 2 is now the designated destination for the Stardust Mission which is a $202 million Discover-class mission that was launched in February 1999 for a rendezvous with Wild 2 in January, 2002. It will use aerogel collectors to collect several 1000 dust grains from the coma of this comet, and then return to earth by January 2006 to be recovered. Another Stardust page is over at the Discovery Mission office at NASA Headquarters.

The Principle Investigator for this mission is Dr. Donald Brownlee at the University of Washington.