Fig. 13. Self-de ploy able planar concept. reduce the cost of the array. Examples of cost and efficiency improvements being worked on are (1) “transparent arrays” which allow thermal energy to pass through the cell assembly thereby allowing much lower and more efficient array temperatures, (2) “multi-bandgap solar cells” where several photoelectric junctions are stacked one on top of another to make use of the total sunlight spectrum, (3) “thin film” solar cells which can be sprayed or vacuum deposited on lightweight plastic blankets, and (4) improved concentrator systems which can significantly reduce the area of solar cells needed. One major technology limitation in the use of space today is the ability to put large amounts of weight in geosynchronous orbits. Our present orbital transfer vehicles (OTVs) can lift only 5,000 lbs from the low shuttle orbits to geosynchronous orbit which is the most efficient orbit for power generation and the best suited for communications and Earth surveillance. Extremely lightweight power sources are therefore critical to our program planning in the 1990s and early 2000s. Beyond that time frame it is assumed that improved OTVs will be available. It is not obvious at this point in time which kind of solar cell or which array design will prove to be best suited for a particular mission; however, the conclusion of our studies at Lockheed have shown that “photovoltaics” — the simple, safe, solid-state conversion of sunlight to electrical energy — can provide unlimited power for our future space activities.
RkJQdWJsaXNoZXIy MTU5NjU0Mg==