Technology Bulletin

Space fastener finds an earthly home

A quick-connect nut designed for the easy assembly of components in space will soon come to Earth. A user may install the nuts simply by pushing them onto standard bolts, then giving a quick twist. To remove, just unscrew. NASA's Marshall Space Flight Center (Huntsville, AL), signed a licensing agreement with M&A Screw and Machine Works (Philadelphia) for the design, which evolved from the Pathfinder technology program--a NASA project dedicated to in-space assembly techniques. The nuts have many potential uses. Bruce Weddendorf, the engineer who invented the fastener in a Marshall Center laboratory, sees possibilities for using quick-connect technology undersea for assembling oil-drilling platforms. Other applications include the erecting of barriers for mines, the assembly of underwater salvage equipment, fire-fighting equipment, scaffolding, assembly-line machinery, industrial cranes, and lug nuts on racecars. Quick-connect nuts typically are more than three times the size of common nuts and must be custom-made, ranging in cost from $35 to more than $200 a piece. E-mail: Jerry.Berg@msfc.nasa.gov

It's cool to keep things cool with thermoelectricity

In conventional cooling devices, heat is carried away by a working fluid, such as a chlorofluorocarbon, which involves by moving parts prone to equipment breakdowns, environmental damage, and bulkiness. In thermoelectric devices, the "working fluid" is electrical current that runs through a junction between differently doped semiconductors and pulls heat away from that junction, producing cooling without any moving parts. And while the theory behind thermoelectric devices has been around for many years, current materials don't rival the efficiency of compressor-based devices. Enter Francis DiSalvo, professor of chemistry and chemical biology at Cornell University (Ithaca, NY). In a program funded by the U.S. Office of Naval Research, DiSalvo is developing new thermoelectric materials to make this a more viable cooling alternative. According to DiSalvo, the search is complex because with the exception of designing organic molecules based on carbon, the ability to predict the composition and structure of materials made from three or more elements is completely lacking. "For most of the elements in the periodic table, we don't know what will happen when we put them together. If we knew how to do that, then we could calculate from the structure what the thermoelectric properties might be like. And the theory is good enough now that the results would be fairly accurate," he says. His research focuses on uniform bulk materials, which can be prepared in large amounts by traditional synthetic methods, and on compositionally modulated films, which require expensive nanofabrication. Bulk materials primarily have applications in large devices like home refrigeration and recovering power from car heat exhaust, while modulated film research might be applicable to niche markets like on-chip cooling (see Design News 10/18/99 cover story). Researchers know they need a material with low thermal conductivity and high electrical conductivity, which has led them to look at compounds of heavy elements like lead, antimony, bismuth and tellurium. "We have some compounds that looked promising based on platinum." And although platinum is way too expensive, DiSalvo says, "if we can do the proof of principle, then we've got our foot in the door." DiSalvo's article, "Thermoelectric Cooling and Power Generation," appeared in the July 30 issue of "Science." E-mail: deb27@cornell.edu.   

Listen to Mars via the Internet

When the Mars Polar Lander touches down on the South Pole of Mars the beginning of this month, researchers will be all ears. Piggybacked on the Russian Science Academy LIDAR experiment is the Mars Microphone. This small 50g device will relay what it "hears," whether the wind blowing against the Lander or the Polar Lander's robotic arm, back to earth. Mars, unlike the Moon, has enough of an atmosphere to allow sound waves to travel and therefore to be heard and recorded. Researchers expect Mars' sounds to be similar to that under similar conditions here on Earth, except much fainter because of the thinner atmosphere. Although Carl Sagan proposed the idea for the first Viking mission in the mid seventies, the RSC-164 speech recognition chip developed by Sensory, Inc. (Sunnyvale, CA) and manufactured by Taiwan Semiconductor Manufacturing Corp. (Hsin-Chu, Taiwan), recently made this project a reality. The microprocessor, originally designed for voice activated, consumer-based electronics, will sample signals from the microphone at 8-bit resolution and perform 2- and 4-bit compression before storing the data. The processor will select and process 10 seconds of the loudest sounds for storage in the onboard flash RAM, where the data is then read out of the Lander telemetry system through the LIDAR data interface. The sounds will be transmitted back to earth and made available over the Internet when NASA signals the device. For information on the chip, e-mail: bruce@sensoryinc.com.  To listen to an actual Martian sound, visit: www.sensoryinc.com/html/Mars.asp.