Documents / Report
This Defense Intelligence Reference Document, prepared by the Defense Intelligence Agency under its Advanced Aerospace Weapon System Applications (AAWSA) Program and dated 14 December 2009, is a white paper on programmable matter and smart materials. It covers quantum dots, metamaterials, liquid crystals, dynamic windows and spacecraft thermal management, and describes a future space station scenario. It concludes that even partial realization could bring significant gains in spacecraft energy efficiency, safety and mission flexibility.
UNCLASSIFIED/ /P9R: 8PPIIIAk Wli&i a•1uc In addition, sharp temperature discontinuities can be an energy source. A Peltier junction can be run in reverse so that heating one side of it and cooling the other produces a voltage. This seems quite straightforward at the sunlight terminator of a spacecraft-the line dividing the sunward and shadowed faces. Here, although there exists very little direct solar energy, the temperature gradient can be quite steep, indicating a potentially quite large amount of harvestable energy that would otherwise go to waste. Still another way to harvest energy is through the piezoelectric effect-a voltage generated when certain materials are under pressure. Because the atmosphere within the spacecraft exerts a constant outward pressure on the hull, this seems a good candidate for energy scavenging as well. In addition, for areas of the spacecraft interior that are expected to receive intermittent pressure (for example, because crew members bump up against them), this energy can be harvested as well. The total energy of these interactions may not be very large, but for programmable materials that would otherwise be sitting idle, energy scavenging is an excellent activity even at very low efficiency. Smart materials can also be used to store the energy they generate. A capacitor is simply a pair of conductors with an insulator between them, which can separate charges under the influence of a voltage, sending electrons to one side and holes to the other. This separation of charges, like the separation of chemical ions in a battery, stores energy. Automotive ultracapacitors have a bright future, and replacing their "holey carbon" with nanostructured programmable materials may allow storage of even more concentrated charges. Superconducting loop batteries are another possible storage mechanism, particularly on the shadowed side of the spacecraft, where cryogenic temperatures are easily achieved. Advanced Concepts in Programmable Materials Programmable materials can assume novel, unnatural configurations, but their primary advantage is that their properties can be changed on demand. Thus, it becomes possible, for example, to reconfigure a single spacecraft attitude sensor to operate as a sun sensor, horizon sensor, or star sensor, as required. The same technology can convert any black-and-white imaging sensor into a multispectral sensor-at low cost and with no moving parts. In fact, a single device could be a receiver for optical or infrared signals, a tunable optical or infrared filter, or a precision light source for calibrating other sensors. In addition, when not in use, the device can serve as a photovoltaic cell, converting sunlight into additional electricity. In fact, the inherent re-programmability of the material properties means devices incorporating dynamic materials can be adapted to novel purposes that were not anticipated at the time of manufacture. In the future, dynamic materials may serve in such applications as polarizers, magnetic and electric field sensors, and color-changing solar sail controllers for station keeping. This open-ended flexibility has the potential to dramatically improve the value and performance of spacecraft that lie beyond our current capabilities. 12 UNCLASSIFIED/ ;CEiOAt OFFIGilk WE&i O•lklf
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Report, from the dia collection. The PDF is mirrored here; the original link is above. 20 pages are in the text index: search them above, or from the library's search.