The Surface of Mars: The View from the Viking 2 Lander

Abstract

Viking 2 lander began imaging the surface of Mars at Utopia Planitia on 3 September 1976. The surface is a boulder-strewn reddish desert cut by troughs that probably form a polygonal network. A plateau can be seen to the east of the spacecraft, which for the most probable lander location is approximately the direction of a tongue of ejecta from the crater Mie. Boulders at the lander 2 site are generally more vesicular than those near lander i. Fines at both lander sites appear to be very fine-grained and to be bound in a duricrust. The pinkish color of the sky, similar to that observed at the lander I site, indicates suspension of surface material. However, the atmospheric optical depth is less than that at the lander I site. After dissipation of a cloud of dust stirred during landing, no changes other than those stemming from sampling activities have been detected in the landscape. No signs of large organisms are apparent at either landing site.

One Mars Year: Viking Lander Imaging Observations

“…One possibility is that either the surface layer or the material immediately below the sediment layer developed a crust by some type of cementation of fines. This would not be completely unexpected since a duricrust layer has been described at both sites (7,13).…”

“…Also, during the 102 seconds required to obtain an image, at least some images should have shown lighting fluctuations if there had been dust turbulence in the boundary layer or differential concentrations of dust passing above the spacecraft. In an extreme case one might expect images similar to the first ones obtained by each lander (7,13), which show lighting variations due to dust that was entrained in the retrorocket exhaust during touchdown and remained suspended long enough to be imaged. No equivalent lighting variations due to suspended dust have since been recorded.…”

Extraterrestrial Arid Surface Processes

“…As previously noted, the landscape of the Phoenix landing site was characterised by sorted stone patterns, polygonal terrain and a shallow ice table (Mellon et al, 2009;Levy, Head and Marchant, 2009). Polygons were also observed at the Viking 2 landing site (Mutch et al, 1976b;Jones et al, 1979). Some of the most striking evidence for periglacial processes was documented by Balme and Gallagher (2009) from the equatorial regions.…”

“…Viking 2 landed on the northern plains of Mars at Utopia Planitia on the ejecta blanket of Mie crater (Mutch et al, 1976b). A flat landscape supported large numbers of blocks, some more than 20 cm across, scattered with a much higher density than at the Viking 1 site.…”

“…Soil-like features have been observed at all landing sites to date, including resistant layers (Viking 1 and Viking 2, Mutch et al, 1976aMutch et al, , 1976b, highly variable mechanical properties of fine-grained surface materials from unconsolidated to high compressive to strong resistant (Pathfinder, Ward et al, 1999), enrichment in salts related to moisture (Opportunity, Soderblom et al, 2004) including those of sulfur, chlorine and bromine (Spirit, Haskin et al, 2005;Crumpler et al, 2005), carbonate deposition (Phoenix, Boynton et al, 2009) and ice segregations (Phoenix, Smith et al, 2009). Further studies of soil profiles and processes on Mars await future surface missions able to trench or core deeper into the soil and perform detailed analyses at various depths.…”