MAGELLAN PROJECT OFFICE

                             P-38741
                             8/12/91

This remarkable "half crater" is located in the rift between Rhea
and Theia Montes in Beta Regio.  Radar illumination is from the
left.  The as yet unnamed crater is 37 (23 miles) kilometers in
diameter and is located at latitude 29.91 degrees north,
longitude 282.9 degrees east.  It has been cut by many fractures
or faults since it was formed by the impact of a large asteroid. 
The eastern half of the crater has been completely destroyed
during the formation of a fault-valley that is up to 20
kilometers (12 miles) wide and apparently quite deep.

A north-south profile through the very center of this crater is
visible as a result of the downdropping and removal of the
eastern half of the crater.  This "profile view" gives a third
dimension to the crater.  Thus it will be beneficial to
"illuminate" this area from the opposite side (right-looking)
with the Magellan SAR during a later mapping cycle, permitting an
even more detailed view of the geologic structure of this
feature.

                    Jet Propulsion Laboratory
               California Institute of Technology
          National Aeronautics and Space Administration
                     Pasadena, Calif. 91109
    Pasadena, Calif. 91109