Focusing on the Big Picture
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Even scientists have to remember to keep perspective. . . . of their
rover's landing site that is. This image of the FIDO field site is an example
of the types of images that scientists can generate from the data that
instruments on Mars Global Surveryor and Mars Odyssey are gathering in
preparation for the 2004 landing of the Mars Exploration Rovers.
"Orbital images give us the overall regional geological context
for a site. If we didn't have an overall view, and we saw a rock that
seemed out of place, we would question what it was doing there. For
instance, if we didn't have orbital data, we would have wondered what a
dark volcanic rock like Woodstock
was doing in a lighter area with no other dark rocks like it. Because we
had the orbital data, we were able to see evidence of a lava flow in
the general region, and it made sense," said scientist Jeff
Moersch, a science team member from the University of Tennessee.
"Orbital images allow us do long term strategic planning for
where rover will go over the next days. If there's something interesting
that rover can't get to today, we can see it and go there later,"
commented Moersch. Prior to seeing the orbital remote sensing images of
FIDO's location, the team hadn't considered visiting an area south of the
landing site. However, upon viewing these images, they discovered an
area that had a distinct boundary indicating a different rock type
(see inset). Boundaries are interesting because one rock type might be
layered on top of another rock type and the depositional history of the
layers tells a story about how the land was formed.
Scientists are able to use a combination of the orbital data and field
work done by the rover to validate hypotheses about what types of soil
and rock cover a region. "When you do exploration field geology
on Earth, you often get orbital data first. Then you do spectral analysis
on that data - determine what minerals might be in the soil by their color.
The final step is to go to the field and validate your hypothesis. That's
just what the FIDO rover is doing for us now (and what the Mars Exploration
Rovers will do on Mars) - it acts like a field geologist on the ground."
This particular image was created by combining a color image derived
from multispectral data with a black and white high resolution image -
both taken as if from space (these are truly aerial pictures). The black and white image has a resolution of
7 meters (23 feet) per pixel while the color image has a lower resolution of
30 meters (98 feet) per pixel. By combining the two, scientists are able to
see color variation and substantial detail in the terrain all in the same image.