The Cylindrical Electrostatic Liquid Film Radiator for Heat Rejection in Space

A new space radiator concept has been proposed (Kim et al., 1991, 1992a, b, 1993) in which a thin film of hot liquid, flowing along the inside of a closed membrane, rejects waste heat by radiation to the surroundings. In previous versions, the radiator rotates, supplying most of the driving force for the liquid flow. In the present design, the cylinder is stationary, and the liquid flows circumferentially under its initial momentum. Moderately large Reynolds numbers are required to overcome viscous drag, and prevent excessive thickening of the film. The major design consideration involves the application of an internal electrostatic field to pull the liquid away from the site of a membrane puncture due to micrometeorite impact. Calculations are presented that show that leaks can be stopped with a safety factor of two or more, while the surface wave thus produced is washed harmlessly out of the system. Some preliminary heat transfer performance characteristics are presented. The advantages of this concept include the absence of moving parts and the ease of deployment, compared to rotating units, and a factor of at least three for the reduction of the weight per unit surface area compared to heat pipes.

The chemistry of carbon in the lunar regolith

The current status of knowledge concerning the chemistry of carbon in the lunar regolith is discussed. The respective roles of the solar wind and micrometeorite impact in contributing carbon and providing energy to stimulate chemical reactions and mobilize carbon phases are examined. Most detailed information has been obtained by releasing trapped species and decomposing reactive carbon phases by dissolution of lunar soils in concentrated deuterium labelled acids. The method has substantiated that hydrocarbons deriving from solar wind implanted carbon and hydrogen are present in the silicate. In addition to trapped species, a number of carbon phases chemically bound to the matrix have been recognized. The most important of these are an acid hydrolysable species associated with metallic iron and what appears to be a discrete ionic carbide which liberates acetylene. Although the majority of the solar wind implanted carbon may be released and quantitated by pyrolysis there is little information to identify which elements were bonded to the carbon in the sample, if indeed any bonds were present at all.

2.3.3 Micrometeorite Impact Craters on Skylab Experiment S 149

During the Skylab experiment S 149 three different sets of areas were exposed. 71.5 cm2 were facing the sun for 46 days, and 36 cm2 for 33 days, whereas 77.5 cm2 were exposed in anti-solar direction for 34 days. A fourth set is currently being exposed with the hope of future recovery. The exposed surfaces consisted of stainless steel, aluminium, platinum, glass, and pyroxene. The recovered targets have been investigated with a light microscope and a scanning electron microscope. We found two groups of possible impact structures:1.) Five craters between 1 and 30 µm. These craters show clear signs of hypervelocity impact. Measurements yielded diameter to depth ratios between 2 and 3. Chemical investigations in the craters yielded an enhancement in aluminium in one case.2.) 44 crater-like structures between 1 and 4 (µm in diameter. These features have been found on 4 cm2 of pyroxene exposed in solar direction. They show diameter to depth ratios between 5 and 8. Chemical measurements of the interior of these structures indicate the elements of the pyroxene composition.The five impacts of the first group correspond to a cumulative flux of the order of 10−4 (m−2s−l) for masses of about 10−12 g. The second group may indicate a fragmentation process at altitudes around 450 km. Considering these 44 crater-like structures having been produced by fragments of one projectile, the impact rate could be comparable to that calculated for the first group. If individual projectiles had produced these structures, the corresponding flux could be 2 orders of magnitude higher.