No abstract

The presence of longitudinal ridges documented in long runout landslides across our solar system is commonly associated with the existence of a basal layer of ice. However, their development, the link between their occurrence and the emplacement mechanisms of long runout landslides, and the necessity of a basal ice layer remain poorly understood. Here, we analyse the morphometry of longitudinal ridges of a martian landslide and show that the wavelength of the ridges is 2–3 times the average thickness of the landslide deposit, a unique scaling relationship previously reported in ice-free rapid granular flow experiments. We recognize en-echelon features that we interpret as kinematic indicators, congruent with experimentally-measured transverse velocity gradient. We suggest that longitudinal ridges should not be considered as unequivocal evidence for presence of ice, rather as inevitable features of rapid granular sliding material, that originate from a mechanical instability once a kinematic threshold is surpassed.

In-Situ Resource Utilization (ISRU) of lunar materials for the establishment of an extra-terrestrial human base or settlement will involve guarding against, as well as utilizing, the ever-present, clinging, penetrating, abrasive, resource-rich, fine-grained lunar dust. The properties of the fine portion of the lunar soil (<50 µm), its dust, must be adequately addressed before any sustained presence on the Moon can be fully realized; these include: 1) abrasiveness, with regards to friction-bearing surfaces; 2) pervasive nature as coatings, on seals, gaskets, optical lens, windows, etc., 3) gravitational settling on all thermal and optical surfaces, such as solar cells; and 4) physiological effects on the tissue in human lungs. The chemical and physical properties of the fine fraction of lunar soil is at the root of the unusual properties of the dust that contribute to its deleterious effects-its "liability". Recent discoveries of the unique magnetic properties of lunar mare and highland soils by the senior author's Tennessee group have led to suggested solutions to the liability of the lunar dust. The soil fragments and dust grains contain myriads of adhering nano-sized (3-30 nm) Fe 0 particles, iron in its elemental form, concentrated especially in the fine, dusty fraction. The presence of this ferromagnetic Fe 0 on and in almost every grain of the fine dust-sized particles imparts an unusually high magnetic susceptibility to the particles, such that they are easily captures by a magnet. Furthermore, the presence of these nanophase Fe 0 grains imparts an unusual property to the soil for microwave energy. The microwaves couple strongly with the Fe 0 to such a degree that a sample of Apollo soil placed in an ordinary 2.45 MHz kitchen microwave will literally begin to melt before your tea-water boils. Further considerations of the properties of the fine soil are the basis for the microwave sintering/melting, hot-pressing, and extrusion of the soil to form various construction materials, in order to realize some of the "assets" of the soil

resource development is challenging, but possible, with products that are useful in space or, in limited cases, on Earth. Proper utilization of these resources, in the establishment of lunar habitations and as fuel for planetary exploration, will provide an invaluable stepping-stone for humanity as it grows beyond the limits of Earth and of our Solar System. Near term uses of these resources can have economic implications in space industrialization and opening up virtually unlimited sources of energy for a growing world economy. Scientific and economic considerations must be melded into plans for future lunar exploration and development, and commercial interests can be expected to join the scientific and technical objectives that have formed the basis for previous lunar exploration programs. This chapter addresses the major topics that must be considered in developing a strategy for the exploration and development of the Moon: • Why go to the Moon? The objectives of lunar exploration will be based on human society's need for more information, energy, and raw materials that constitute the principal underpinnings of economic growth. The chief themes addressed here are the expansion of humans into space, space industrialization (possibly including tourism), space transportation, the search for more energy, the Moon as a laboratory for planetary science, and astronomy and other science on the Moon. • Getting There and Back. Although the Moon is near enough to Earth to be considered part of an economic system with Earth, routine and safe transportation within the Earth-Moon system will need to be developed.

No abstract