It's pretty well established that the "branches" are depressions not raised regions from the direction of illumination:
The sublimation of Mars’ southern seasonal CO2 ice cap and the formation of “spiders’’.
Sylvain Piqueux, Shane Byrne and Mark I. Richardson.
Division of Geological and Planetary Sciences, California Institute of Technology,
Pasadena, California 91125.
"Figure 1 shows examples of radial structures observed in the southern polar latitudes with the MOC narrow angle camera. The term “spiders” was originated by Kieffer [2000], and we use this term in this paper. The features displayed in figure 1 are characteristic of
what we have mapped throughout our region of interest. Spiders are typically
characterized by a central depression with irregular troughs radiating away. The spiders are shown to be “negative” features (depressions rather than knobs) based on illumination. These troughs merge and branch in an irregular and seemingly random pattern. "
p. 6.
http://www.gps.caltech.edu/~shane/piqueux.pdf
Bob Clark
Space/Science » in reply to Re: CO2 and the martian
Re: CO2 and the martian
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- CO2 and the martian "spiders"