In mid-February, before and after MESSENGER's latest perihelion (closest
approach to the Sun), an imaging campaign was conducted to search for
vulcanoids, small rocky bodies that have been postulated to exist in
orbits between Mercury and the Sun. Those images are still waiting to be
transmitted to Earth. Read the full news story for details about the
possible existence of vulcanoids and MESSENGER's unique opportunity to
search for them. The image here is from the first set of 240 MDIS images
taken to look for vulcanoids, acquired in June 2008. It is a 10-s exposure
taken through the WAC's clear filter. Jupiter is bright and visible in the
image. The camera field of view is nearly large enough to capture the
entire width of Sagittarius, a constellation of the zodiac visible low and
to the south in summer from temperate latitudes in the northern hemisphere.
The Greek letters identify some of the brighter stars in Sagittarius.
During the vulcanoid search campaign, 4-5 images of the same scene are
taken back to back. This procedure allows cosmic ray strikes on the
camera's detector to be identified and enables fainter objects to be
detected. One such cosmic ray strike is labeled on this image. In this
single image, the cosmic ray strike appears similar to the stars, but in
the four images taken immediately after this one, the cosmic ray strike is
gone whereas the stars remain. Images are also taken hours and days apart,
so the motion of objects in the sky can be determined. If a vulcanoid were
imaged, its motion through the sky would appear very different from
motions of the background stars and known Solar System objects. No
vulcanoids have been found yet, but the latest set of acquired images will
expand the volume of the search region examined so far.
Date Acquired: June 4, 2008
Image Mission Elapsed Time (MET): 121050477
Instrument: Wide Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
WAC Filter: 2 (clear filter)
Field of View: The WAC has a 10.5° field of view
These images are from MESSENGER, a NASA Discovery mission to conduct the
first orbital study of the innermost planet, Mercury. For information
regarding the use of images, see the MESSENGER image use policy.