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Last week, we presented our
best image of Viking Lander 2,
which had not been seen for nearly 30 years, as well as a
candidate for the Mars Polar Lander site. Before these
Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC)
images were taken, we tested out the techniques needed to image landers
on the martian surface by observing Viking Lander 1 (VL-1) and Mars
Pathfinder (MPF). Here we review our best images of these earlier targets.
Viking Lander 1
The first figure (above) visually tells the story of
how VL-1 was found. The initial observations of the location of Viking
1, as originally determined by members of the Viking science team
based on sightlines to various crater rims seen in the lander images
(left frame), did not show the detailed
features we knew from the lander pictures to be in the area. Using geodetic
measurements, the late Merton Davies of the RAND Corporation, a MGS MOC
Co-Investigator, suggested that we should image areas to the east
and north of where VL-1 was thought to be. Timothy J. Parker of the
Jet Propulsion Laboratory (Pasadena, California),
using sightlines to crater rims seen in the VL-1 images, deduced
a location very similar to that suggested by Davies. Our image of
that location showed additional, near-field features (rocks associated
with a nearby crater) that closely matched the VL-1 images (center and
right frame, where B denotes "Volkswagon Rock"). The inset
(upper right) is an enlargement, showing the Viking 1 lander.
Mars Pathfinder
As with previous observations of the Mars Pathfinder (MPF) site, we primarily
used sightlines to North Peak and the Twin Peaks (second image, left frame).
These large, very obvious horizon features make finding MPF fairly easy.
The enlargement of loci of the various sightlines (second image, right)
shows what we believe
are Mars Pathfinder (the larger, lighter-toned spot, arrow) and
the 1 m diameter boulder, "Yogi" (dark dot above the MPF).
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