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This Defense Intelligence Reference Document from the Defense Intelligence Agency, dated 1 November 2010, was produced under the Advanced Aerospace Weapon System Applications (AAWSA) Program. It describes nanosatellite technologies and proposes launching nanosats into orbit with laser Lightcraft propulsion. It also covers a weapon mission selection study and multi-megawatt laser options. The author recommends that the Department of Defense and NASA bring Lightcraft R&D back to the United States and restart the X-50LR flight demonstration program.
UNCLASSIFIED//EAR AEEJGJPk WEE &••LY inclination relative to the ecliptic, will reduce the maximum eclipse period to about one hour. Inclusion of spacecraft batteries is then justified. Passive thermal control will be used to keep the spacecraft electronics within 10°c of ambient temperature, and hence will not require electric power for heating. Using such a scenario, a battery requirement of about 2 amp-hours at 3.3 volts will allow full spacecraft functionality during an eclipse. Twelve AA size Lithium-ion batteries meet the requirement and only weigh 480 grams. Circuits that have high current demands, such as thruster solenoids and fuses, need to be augmented with components that have a lower power density than batteries, but also have lower internal resistance. Ultra-capacitors are being explored for this application. Miniaturization of the power system electronics (PSE) to meet the weight and size requirements of the nanosats is a considerable challenge. The ideal approach is to eliminate the PSE completely, by having a fixed electrical load and batteries provide the needed bus regulation. This yields a simplified system consisting of solar cells, batteries, and minimal circuitry. A more immediate approach to miniaturization is to produce hybrid modules that measure approximately 5.08 cm x 3.17 cm x 1.27 cm and weigh 100 grams for each PSE component, namely the solar array regulator, battery regulator, and low voltage power converter. The combination of these three components into one module will reduce the size and weight another order of magnitude. THERMAL Although an inclination change by 10° renders maximum shadows below two hours, we evaluate the case of a maximum eight hour shadow for the purpose of generality. Three thermal configurations are considered: (1) top and bottom of the nanosat are insulated, the inside of the cylindrical solar array is not insulated, allowing internal heat transfer between the internal equipment and the array; (2) the entire nanosat is insulated, top and bottom as well as inside the solar arrays, except for a radiator on top, sized to radiate the internal electrical dissipation; and (3) the internal equipment is thermally isolated as well as possible from an "outside shell" with a controllable two- phase heat transport device which can be "shut off" during Earth shadows, serving as the only thermal coupling between the equipment and a radiator on the outside surface. The key advantage of configuration (1) is its reliability, or robustness. Since the temperature of the nanosat is set by a high energy balance (heat in - heat out) dominated by the absorbed solar energy, the operational temperature of the nanosat is relatively insensitive to top and bottom multilayer insulation (MLI) properties, or, largely, to internal heat dissipation. However, the feature that yields the operational reliability, i.e., the high energy balance, also results in a rapid drop in temperature when the solar load disappears during the Earth shadow. During the maximum eight hour eclipse used for this evaluation, it was found that internal temperatures dropped by about 60 8 C, which would result in internal temperatures in the range of -30 8 C to -40°C. At the same time, the solar arrays dropped to a temperature of about 60°C. Based on past experience, these end-of-eclipse temperatures are reasonable. 6 UNCLASSIFIED//FQA: QFFIGI11J.k WEE Q•lklf
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Report, from the dia collection. The PDF is mirrored here; the original link is above. 77 pages are in the text index: search them above, or from the library's search.