The following four slides were generated at the Earth and Planetary Remote Sensing Laboratory at Washington University in St. Louis headed by Dr. Raymond Arvidson. It must be noted that all but slide #29 have undergone extensive image processing (see Appendix) and none except the last slide shows the true color of the surface.

27. Drifts at VL-1

Wind-sculpted aeolian deposits are common at VL-1. They are termed “drifts” rather than “dunes” because their surface morphology is due to aeolian erosion, not deposition. Internal layering can be seen on the right-hand facet of the drift nearest the lander. The martian sky has a reddish color because there is much less atmospheric scattering to produce a blue sky (the martian atmosphere is much thinner than on Earth) and there are reddish dust particles suspended in the atmosphere. There was some initial confusion about the color of the martian sky because some of the first pictures of the martian surface released had been processed to render the sky blue, as in this and other slides. A “sol” is a martian day, which is 24 hours, 39.6 minutes. July 20, 1976, was designated as sol 0; sol 1 began on July 21 at 12:01 a.m. local time at VL-1.

Frames used: 11B097/040 (high resolution) and 11I059/688 (color triplet).

Click here to view a high-resolution version of the image (1.86 MB)