Of particular interest are the results
obtained when lichen were tested by the LR. The lichen responded very
vigorously upon initial contact with the aqueous nutrient, but the rate of
evolution quickly decreased and essentially ceased after only 24 hours. A
comparison of the lichen incremental responses with those of the Mars LR
is presented in FIG. 8. This suggests the possibility that too much water
could have been a factor in both experiments. The above cited publication
argues that increased gas evolution upon the second injection would have
supported the biological nature of the response. However, had a second
evolution of gas occurred, might not the argument have been made that
water had become the limiting factor following the first injection, and
that its resupply allowed a chemical reaction to continue?
6. No Visual Evidence: It was
reported78 that a study made by the Viking Lander cameras
showed no evidence for macro or micro forms of life. However, a detailed
analysis of all the Viking Lander images79 revealed colored
spots on many of the rocks and colored areas of the surface ranging from
ochre to yellow to olive and green. A digital spectral analysis of the
spots on the rocks as seen in six imaging channels (RBG and three near-IR)
comported closely to that of images of lichen-bearing rocks. These rocks
were viewed by the Viking cameras in the simulated Viking 1 Lander site
and processed through the Viking Imaging System. The greenest objects in
both fields of view were spots on the martian and Earth rocks. The
respective digital numbers for hue, saturation and color for the spots in
both images were similar. Subsequently, the greenish colors were
independently confirmed80,81 with the additional observation
that the green spots on the rocks were elevated by 0.1 to 1 mm above the
background surface of the rock. While unusual weathering might account for
the elevation of the spots and the changes observed, it has been
suggested82 that lichen, or similar colonial microorganisms,
could more readily satisfy the observations. Called "the pioneers of
vegetation", lichen are the first life forms to appear on bare rock.
Lichen have also been reported83 to subsist when the only
source of water is atmospheric vapor. The atmosphere at both Viking Lander
sites was at or near water vapor saturation diurnally, and frost was seen
in many of the morning images.
FIG. 9 is an image of three near-field rocks at Viking
site 1 which were selected for study. The image was calibrated by the
Viking Imaging System to provide the truest Mars colors. FIG. 10 is a
heretofore unpublished set of 3 images encompassing most of the same area
and taken at intervals of one martian year (two Earth years). All three
images are treated identically, and closely approximate the calibration of
FIG 9. The pictures are taken within several degrees of the same sunangle
in order to permit comparison without mistaking light or shadow effects
for true differences between successive images. The field of view was
limited because of power conservation during the later portion of the
extended mission. It is apparent that changes have occurred over time.
Some of the near-field differences between the first two images were
caused by sampling of the soil that occurred after the first image was
taken. However, changes in both the near and distant fields cannot be
associated with the sampling activity. A comparison of the same near-field
fine surface structures among the three images shows that aeolian effects
were essentially nil (the only apparent changes being from slumping that
occurred around the dug hole). In particular, attention is directed at the
foreground rock, which exhibits a major change in its patterned colored
areas, and to the distant background where extensive pattern and color
changes are evident. In several ways, then, the Viking Lander images
provide evidence consistent with a biological interpretation of the LR
data.
