4.4.6 Maintenance

4.4.6.1 Repairs and Replacement

The plastic cover must be durable enough to withstand sand and soil particle impact during sandstorms, wind, UV radiation, temperature variations and physical stress from soil and rocks underneath as well as from any surface vehicles that drive over it (by the latter we mean small, robotic vacuum cleaners and related vehicles). Given the costs of replacement, it may be more economical to repair the cover than replace it.

To extend the field lifetime of the cover, small torn places could be covered using a patch or a spray-on coating. The coating could consist of a mixture of lime or titanium dioxide with a binding agent. An UAV or a ground-based robot repair unit could apply the coating.

Once a section is no longer suitable for field use, it could be removed and the plastic recycled to make new plastic. The logistics of how repairs and replacements are made over such large areas will require considerable planning.

4.4.6.2 Cleaning

4.4.6.2.1 Contamination Sources

All deserts are subject to periodic sandstorms/dust storms. Blowing sand and soil accumulate on surfaces. In addition, in areas where dunes are the dominant feature, winds will cause the bulk surface sand to migrate and eventually cover surface objects. In the areas of interest to this project, it is the blowing particulate matter that is of concern.

Deposition of this material on the surface of the cover can be expected to reduce the albedo significantly, from 0.8 to possibly as low as that of the original surface matter, 0.2-0.4. We believe this can be best addressed by a combination of preventative measures and use of robotic vacuum cleaners, because removal of the plastic and cleaning it either on-site or off-site is just too expensive.

Precipitation, either as rain or snow, should probably just be allowed to evaporate or run off. By including drainage holes in the plastic, excessive ponding of water could be prevented. Rainfall is too infrequent to be counted on to wash contamination away.