MAGELLAN PROJECT OFFICE

P-38156
5/10/91

     This Magellan image, centered at 42.5 degrees south latitude,
6 degrees east longitude shows Pandora Corona.  It is 350
kilometers (210 miles) in diameter and is located in Lada Terra.
It lies beside a northwest-southwest trending fracture zone.  Many
of the radial fractures in Pandora's interior appear to connect
with this fracture zone, suggesting that both features may have
formed at the same time.

     Coronae are circular to elliptical features marked by a ring
of concentric ridges, and are thought to result from heat flow from
the planet's interior.  As hot material rises, it weakens the upper
layers of the planet and causes the surface to dome upwards.  Then
s the region cools, the dome begins to subside.  As the upper
layers rise and subside, they are subjected to stresses which crack
the surface, creating both circular and radial fractures.

     The medium grey lobes on the southern side of Pandora's outer
ring are lava flows which began in fissures, or cracks, along the
outer ring.  The irregularly shaped features, aligned in a radial
direction, are thought to be lava collapse tubes.  Molten lava can
flow in long channels near the surface; when the flow stops, these
structures may become unstable and collapse, creating depressions
on the surface.  The small crater in the northeast corner of the
image is 12 kilometers (7.2 miles) in diameter.


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