[meteorite-list] Latest MESSENGER Images Show Fascinating Views of Mercur...

Tue Jan 22 18:26:52 EST 2008

Hi,  Thanks for the post.  I had to  remember to breath!

Dr. Love had said there is a chance that meteorites  from Mercury are already 
in some collections.  What is the current view of  Mercurian Meteorites on 
Earth.

Thanks,  Tom

In a message  dated 1/22/2008 4:53:15 P.M. Central Standard Time, 
baalke at zagami.jpl.nasa.gov  writes:

http://messenger.jhuapl.edu/news_room/status_report_01_20_08.html

MESSENGER  Mission News
January 20,  2008

------------------------------------------------------------------------
Latest  MESSENGER Images Show Fascinating Views of Mercury's  Surface
------------------------------------------------------------------------

MESSENGER  Views an Intriguing Crater

MESSENGER's Narrow Angle Camera (NAC) on the  Mercury Dual Imaging System
(MDIS) acquired this  view
<http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?gallery_id=2&imag
e_id=127>
of  Mercury's surface illuminated obliquely from the right by the Sun.
The  unnamed crater (52 kilometers, or 31 miles, in diameter) in the
center of the  image displays a telephone-shaped collapse feature on its
floor. Such a  collapse feature, not seen on the floors of other craters
in this image,  could reflect past volcanic activity at and just below
the surface of this  particular crater.

MESSENGER team members are examining closely the more  than 1,200 images
returned from this flyby for other surface features that  can provide
clues to the geological history of the innermost  planet.

The crater is located in the southern hemisphere of Mercury, on  the side
that was not viewed by Mariner 10 during any of its three flybys in  1974
and 1975. This scene was imaged while MESSENGER was departing  from
Mercury from a distance of about 19,300 kilometers (12,000 miles),  about
one hour after the spacecraft's closest encounter with Mercury.  The
image is of a region approximately 236 kilometers (147 miles)  across,
and craters as small as 1.6 kilometers (1 mile) can be  seen.

------------------------------------------------------------------------

Ridges  and Cliffs on Mercury's Surface

A complex history of geological evolution  is recorded in this  frame
<http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?gallery_id=2&imag
e_id=128>
from  the Narrow Angle Camera (NAC), part of the MDIS instrument, taken
during  MESSENGER's close flyby of Mercury on January 14, 2008. Part of
an old, large  crater occupies most of the lower left portion of the
frame. An arrangement  of ridges and cliffs in the shape of a "Y" crosses
the crater's floor. The  shadows defining the ridges are cast on the
floor of the crater by the Sun  shining from the right, indicating a
descending stair-step of  plains.

The main, right-hand branch of the "Y" crosses the crater floor,  the
crater rim, and continues off the top edge of the picture; it appears  to
be a classic "lobate scarp" (irregularly shaped cliff) common in  all
areas of Mercury imaged so far. These lobate scarps were formed during  a
period when Mercury's crust was contracting as the planet cooled.  In
contrast, the branch of the Y to the left ends at the crater rim and  is
restricted to the floor of the crater. Both it and the  lighter-colored
ridge that extends downward from it resemble "wrinkle ridges"  that are
common on the large volcanic plains, or "maria," on the  Moon.

The MESSENGER science team is studying what features like these  reveal
about the interior cooling history of Mercury.

Ghostly remnants  of a few craters are seen on the right side of this
image, possibly  indicating that once-pristine, bowl-shaped craters (like
those on the large  crater's floor) have been subsequently flooded by
volcanism or some other  plains-forming process.

This image was taken 18 minutes after close  approach, when MESSENGER was
about 5,000 kilometers (about 3,000 miles) away  from Mercury. The image
is about 200 kilometers (about 125 miles) across, and  features as small
as about 400 meters (about 400 yards) can be  resolved.

------------------------------------------------------------------------

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.

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