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MGS Image M08-00063
was taken at around 3 in the afternoon 150 km from Crater Lau at 76.25 degrees
South. This newer pond is very nearly circular, around 3 km (1.85 mi)
in diameter. It lies at the bottom of an unnamed pedestal-shaped crater shown
in the false-color context image directly above.
This time the floaters -- there are always floaters in Martian ponds, it seems
-- look more like microscopic views of cells. Again we have the dark nuclei and
the lighter surrounding areas, but in this case some conspicuous "skins" too.
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These bodies show other distinctions from the earlier ones. You can see
some interesting wiggly stuff and so on. Perhaps we're observing a
different stage in their life cycle, or a different variety or species?
They must be quite flat, since they cast no shadows in this or either of
the other two instances. Also as in the other two, they crowd together
along the pond's perimeter.
The scale here measures a relatively crude 5.5 meters per pixel, which as we
already know from the shot of the Darwin pond (4.15
meters per pixel) isn't sufficient to resolve the branches very well... though
you can still see vague hints here and there. This sets a boundary on the maximum
branch thickness at 2 or 3 meters since they DO begin to show up in the Keeler shot at 2.76 meters per pixel.
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Here are croppings from each
of the first three ponds, adjusted to display the same pixel scale so that each
view measures about 550 meters (1800 feet) on a side. At least part of the
visual disparity between the floater groups comes from the varying
resolutions and lighting conditions among the three images. We may also be
seeing slight seasonal variations. Mars Global Surveyor captured the Darwin
image about twelve earth days after the start of the Martian southern spring
(solar longitude was 186 degrees with the first day of spring being 180) while
it captured the other two some 53 days further along (214 and 216
degrees).
Processed source images courtesy of NASA/JPL/Malin Space Science Systems
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