[meteorite-list] MESSENGER: Craters in Caloris

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Sun, 2 Mar 2008 23:06:33 -0800 (PST)
Message-ID: <200803030706.XAA14748_at_zagami.jpl.nasa.gov>

http://messenger.jhuapl.edu/news_room/details.php?id=93

MESSENGER Mission News
February 27, 2008

Craters in Caloris

As MESSENGER sped by Mercury on January 14, 2008, the Narrow Angle
Camera (NAC) of the Mercury Dual Imaging System (MDIS) captured this
image
<http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?gallery_id=2&image_id=171>,
which includes the edge of the planet against the blackness of space.
Much of the foreground shows a portion of Caloris basin, one of the
largest impact basins in the solar system. The two large craters near
the bottom of this image can be identified on the northwestern floor of
the basin on the mosaicked image of Caloris
<http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?page=1&gallery_id=2&image_id=149>
released at MESSENGER's NASA press conference on January 30, 2008. The
large crater in the bottom middle of this image has a diameter of about
70 kilometers (40 miles).

Caloris basin is an area of particular interest to the MESSENGER science
team, since understanding its formation can lead to insights about the
nature of large impacts in the early solar system and the results of
these catastrophic events. In a false-color image of Mercury
<http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?page=1&gallery_id=2&image_id=143>,
also released on January 30, Caloris basin is visible in the northern
hemisphere of the planet as a large, light-colored, roughly circular
feature; the floor of the basin may have some differences in its
composition compared with the darker surrounding surfaces.

The two large craters shown in today's released image are each
surrounded by a "halo" of dark material, like the craters shown in our
release of February 21
<http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?gallery_id=2&image_id=166>.
The smaller of the two craters has an unusual pattern of bright, highly
reflective material on its floor. The fact that both of these craters,
which show different material characteristics, are located within
Caloris basin provides information about the variety and complexity of
processes that have shaped Mercury's surface.

Additional information and features from MESSENGER's first flyby of
Mercury are online at http://messenger.jhuapl.edu/mer_flyby1.html.
------------------------------------------------------------------------

MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and
Ranging) is a NASA-sponsored scientific investigation of the planet
Mercury and the first space mission designed to orbit the planet closest
to the Sun. The MESSENGER spacecraft launched on August 3, 2004, and
after flybys of Earth, Venus, and Mercury will start a yearlong study of
its target planet in March 2011. Dr. Sean C. Solomon, of the Carnegie
Institution of Washington, leads the mission as principal investigator.
The Johns Hopkins University Applied Physics Laboratory built and
operates the MESSENGER spacecraft and manages this Discovery -class
mission for NASA.
Received on Mon 03 Mar 2008 02:06:33 AM PST