When a meteoroid strikes the surface of a planet, material from the
surface is ejected outward at high velocity, often creating rays that
extend over distances far greater than the size of the crater formed by
the impact. During MESSENGER’s second Mercury flyby, MDIS captured images
of impressive rays on Mercury, such as the ejecta prominent around Kuiper
crater (PIA11355) and the extensive ray system associated with a newly
imaged crater in Mercury’s northern latitudes (PIA11356). In both of those
examples, the rays appear bright, which is characteristic of freshly
pulverized rock and indicates that the rays are younger than much of
Mercury’s surface. In contrast, in the upper portion of this NAC image, a
set of dark rays is seen emerging from a small crater. Dark rays are rare
on Mercury, but other occurrences have been identified, such as at Mozart
crater (PIA11024) imaged during MESSENGER’s first Mercury flyby). Mozart
crater is interpreted to have excavated dark material from depth during
the impact event, creating dark streamers. The dark rays from the crater
shown here may have a similar origin, and color imaging from the Wide
Angle Camera (WAC) gathered during the flyby is being used to explore the
nature of these unusual dark rays further.
Date Acquired: October 6, 2008
Image Mission Elapsed Time (MET): 131773885
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Resolution: 520 meters/pixel (0.32 miles/pixel)
Scale: The top of this image is about 530 kilometers across (330 miles)
Spacecraft Altitude: 20,000 kilometers (12,000 miles)
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.
