Technology Bulletin

These materials move when illuminated

Materials like PLZT-a combination of lead, lanthanum, zirconium, and titanium--some day may be used to control space robots and micro machines and transfer information in telephones and optical computers. Such materials are both photovoltaic, producing electricity from light-and piezoelectric, creating motion from electricity. The combination of properties is called photostriction. Photostrictive materials move when illuminated. Now, engineers at Pennsylvania State University are exploring applications for devices that move when light shines on them. Potential uses include remote switches, relays, sound generators, and micro micromotors. Another possible application is scanning tunneling or electron microscopes, where the specimen is placed on a stage in a high vacuum. A properly built platform of PLZT could be moved in the vacuum by shining light from outside without breaching the seal, says electric engineering professor Kenji Uchino. He has already created a two-legged stand that walks very slowly when illuminated. For more information, FAX A'ndrea Elyse Messer at (814) 865-9421.

First all-composite small satellite takes shape

The nation's first all-composite small satellite, designed by Los Alamos National Laboratory and being built through a Los Alamos-industry collaboration, is in the final stages of construction and aiming for an early 1996 launch. "The all-composite structure offers a big advantage in terms of performance," says Steve Knox of Los Alamos' Nonproliferation and International Security Division. "Because the structure is so light-it only weighs 90 pounds-we can deliver to orbit 50 more pounds of payload than a similar-size satellite built with conventional materials." The composite material used for the satellite's framework is a graphite epoxy commonly found in commercial aircraft components. The satellite, called FORTE for Fast On-orbit Recording of Transient Events, will carry electronic equipment for detecting, recording, and analyzing bursts of radio energy arising from near Earth's surface, such as the electromagnetic pulse from a low-technology nuclear explosion. The data FORTE gathers also will be useful for studies of the electrically conducting layer of Earth's atmosphere, and of the physics involved in lightning. For details, FAX John Gustafson at (505) 665-2483.

Space Shuttle main engine sports new turbopump

NASA has successfully completed testing of a new high-pressure liquid-oxygen turbopump, and is ready to fly an upgraded main engine on its first Space Shuttle flight in June. The new pump is expected to increase safety margins and reliability for the Space Shuttle Main Engine (SSME). To create the new turbopump's housing, engineers used a casting process that eliminates all but six of the 300 welds in the current pump. The new pump also uses silicon nitride as the new ball bearing material. Silicon nitride, a type of ceramic, is 30% harder than steel and has an ultra-smooth finish that reduces friction. The new bearings eliminate concerns over excessive wear to the pump-end ball bearing, say NASA engineers. Along with the new turbo- pump, NASA will fly a new two-duct powerhead that is expected to improve fluid flows within the engine system by decreasing pressure, reducing maintenance, and enhancing overall engine performance. It will replace three smaller fuel ducts in the current design with two enlarged


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