In mid-November, Ballistic Recovery Systems (BRS) won a $600,000 award from NASA to develop a parachute for jet taxis. It will be a beefed-up version of the chute the South St. Paul (Minn.) outfit already supplies to Cirrus Design for its four-seater prop planes. Nearly 400 Cirrus aircraft are now flying, and its Duluth (Minn.) plant cranks out two more every day. The Federal Aviation Administration has also approved BRS chutes for retrofitting on certain Cessnas.
Do the giant chutes work? Just ask Lionel Morrison, a Dallas architect. On Oct. 3, shortly after takeoff in his Cirrus SR22, a piece of the left wing came loose, making the plane hard to control. So Morrison pulled the handle that launches a small rocket and deploys the chute. He floated down from 1,500 feet--the first person to land an FAA-certified plane under a parachute. Arguments can often get heated--literally--in part because shouting voices pump tiny amounts of energy into the air. Each sound wave briefly compresses the air, which raises its temperature. When loudspeakers are used in laserlike acoustic devices that amplify the compression cycles and quickly extract heat, sound can be harnessed to serve as a heat pump, for such jobs as refrigeration. In the mid-1990s, NASA exploited this principle to build a "thermoacoustic" refrigerator for use in space. But the cooling system just wasn't efficient enough to compete for down-to-earth applications.
Researchers at Pennsylvania State University have continued to hone the technology. At a December meeting of physicists, Matthew E. Poese and Steven L. Garrett unveiled the guts of an ice-cream display freezer powered by sound. Funded in part by South Burlington (Vt.) ice-cream powerhouse Ben & Jerry's Homemade, the prototype thermoacoustic cooling system caps two decades of work begun at Los Alamos National Laboratory sponsored mainly by the Office of Naval Research.
Existing fridges, freezers, and air conditioners use chemical refrigerants that deplete the earth's ozone layer. Production of these chemicals was banned in 1996. But their replacements are hardly cause for celebration: The new refrigerants are far worse than carbon dioxide in terms of global warming.
If further development of thermoacoustic chilling pays off as expected, it could create truly "green" refrigeration systems. Ultimately, Garrett believes, a thermoacous- tic heat pump could even be hooked up to help power a new generation of hybrid electric cars. -- If you thought rising levels of atmospheric carbon dioxide might benefit farms and forests, think again. A three-year study by Stanford University shows that if current trends in climate change are projected forward, plant growth may not drastically speed up--despite an abundance of CO2. In the study, described in the Dec. 6 issue of Science, researchers exposed 32 plots of grassland to simulated climate conditions with varying levels of water, soil-based nitrogen, CO2, and heat. Contrary to expectations, high levels of CO2 stimulated plant growth only when the other three factors were kept at current levels. Under conditions that included higher temperatures and nitrogen levels--both associated with industrial trends behind global warming--a superabundance of CO2 slowed the expected acceleration of plant growth.
-- Front-projection TVs can provide high-definition pictures on very large flat screens. They avoid the need for a rear-projection system's bulky cabinet, but the projector must be placed directly opposite the screen, which often means rearranging furniture. Now, Silicon Optix in San Jose has developed a chip that corrects for images projected from the side. It will show up next year in a home movie projector from Taiwan's Nexgen Mediatech.