stronger and ultrastiff; at lower-right, an array assembly that had to withstand orbital temperatures exceeding 500 °F requiring the solar cells to be welded together instead of being soldered as normal. In the early 1970s, when NASA had plans for an orbital manned space station, Lockheed conceived and built a new kind of solar array for that mission which departed from the rigid metal-structure arrays just discussed and instead was made of lightweight flexible plastic called Kapton. Shown in the center of Fig. 6, the array was built and tested at Lockheed; it was 30 x 84 ft and would produce 25 kW on orbit. Four of these arrays were to be used on the Space Station to provide a 100 kW system; however, the Space Station program was delayed because of funding requirements for the shuttle so that the 100 kW system was not developed. Later, the Solar Electric Propulsion State (SEPS) program was initiated which would use ion engines to propel spacecraft over interplanetary missions. Figure 7 depicts the SEPS vehicle in flight using our arrays because Lockheed again was selected to develop the solar array power source for this mission. In this case the array had to produce 30 W for every pound of array weight, including structure and deployment mechanisms — a 50% improvement over the Space Station array. Figure 8 is an illustration of the full-scale array wing, developed and built for this program. This array is 13.5 x 100 ft and can be automatically retracted to a compact package only 10 in. thick. Because of the success of the development project and the need to prove out operation of such a large structure in space, NASA has contracted with Lockheed to develop the complete Solar Array Flight Experiment (SAFE). The experiment package will include the array, a structure and mechanism for moving it out of the shuttle cargo bay, and a complete data acquisition system to record operational data during ascent and on-orbit operations. While in flight on the shuttle, the experiment is designed to accomplish several objectives as shown in Table 1. Following the experiment, the array will be retracted, put back in the cargo bay, and brought back to Earth for examination. The experimental solar array wing is shown in Fig. 9. The blanket is composed of 84 panels in a flat-fold configuration which, when deployed, make up the 100 ft array. The wing is of flight design except that only one of the panels, the third from the outboard end, is a full electrical module. It is composed of half 2x4 cm and half 5.9 x 5.9 cm cells. The flight experiment is now complete and in final test. When testing is completed, the experiment will be delivered to MSFC for integration into the OAST-1 payload. The array is shown in an artist’s sketch (Fig. 10) deployed from the cargo bay of the shuttle. 4. SPACE SHUTTLE APPLICATIONS NASA has determined that future Space Shuttle operation may be limited by lack of onboard power so projects have emerged to supplement the shuttle fuel-cell power with solar array power. The basic Lockheed array technology was used on concepts to support these projects which included a power module, Fig. 11, which would have a 60 kW array and its own guidance and control system for operating like a power platform in space, and a Power Extension Package (PEP), Fig. 12, which would mount a 25 kW wing on the end of the Remote Manipulator System (RMS) for shuttle augmentation.
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