Wirt Atmar writes:

>Please understand that no
>one knows precisely the color that the [Sagan Memorial] images should be.
>I set the color to
>values that are very characteristic of the similar soil geologies on Earth,
>most especially those of the area around the four corner region of the United
>States. Indeed, the picture is startling in its similarity to terrestrial
>scenes that can be found on many places on the Earth (southern Africa,
>Mongolia, Chile, and the desert southwest of the US).

There appears to be a color calibration target along the frame of
Sojourner. If you can find the spectral characteristics of the target
swatches, you can do a better job of calibration. (I only say that
because Wirt seems to have an inside track for finding data of this sort.)

Incidentally, the "make it look like Earth" calibration method was the
cause of some erroneous color photos originally released from the Viking
project. The original released photos showed a blue sky; when the Viking
imaging team recalibrated the images using later data, they determined
that the sky was actually red because of scattering from airborne dust.

>Viewing these images is a close as you can get to actually walking on the
>surface of Mars without having to endure a three-year ride out there and
>back.

Something about "three years" rang a bell, but it was a while before I
figured out why: Ferdinand Magellan's first (known) circumnavigation of
Earth also took three years. Magellan set out from Spain in 1519, 478
years ago. I wonder how long it'll take to get to Mars in 2474.

-- Bruce


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