WSF an orbiting semiconductor factory

The Wake Shield Facility in free flight during STS-80.

unexplored until Ignatiev's team revived it in the mid-1980s.

In 1986, they joined forces with nine other companies to form a Center for the Commercial Development of Space - one of several industry-academia partnerships sponsored by NASA -and designed and built the WSF using essentially commercial, off-the-shelf technology. Its purely functional shape made it appear like a factory cast-off: a dull, silver-grey disk with a clumsy arrangement of boxes, rods, tubing and angular shapes attached to one side. The forward-facing side (known as the 'ram') was loaded with avionics and monitoring systems, while the back, or 'wake', side was where the ultra-vacuum formed and the semiconductor films produced.

The main objective of the WSF-3 mission on STS-80 was to grow thin 'epitaxial' films which, it was hoped, could have a significant impact on the microelectronics industry. It was recognised that the commercial applications for high-quality semiconductor devices are particularly critical in the consumer technology areas of personal communications, fibre-optic systems, high-speed transistors and processors and optoelectronic devices. Most electronics are made from silicon semiconductors, but 'compound' semiconductors were anticipated to have even higher performance characteristics. Such semiconductors, and the ultra-vacuum needed to grow them, were only possible using the WSF.

Two major components made up the system: a cross-bay carrier in Columbia's payload bay and the 2,090-kg free-flying satellite, which was carried flat, rather than as a vertical 'wafer'. In total, the Wake Shield hardware consumed almost a quarter of the bay. The satellite was equipped with its own set of cold nitrogen gas thrusters to propel itself away from the Shuttle and its own attitude-control system. It also carried a set of silver-zinc batteries to support its thin-film-growth furnaces as well as powering its heaters, controllers and vacuum-measurement gauges and sensors.

The Wake Shield Facility in free flight during STS-80.

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