Developments to Watch
HEAVENLY WEATHER FORECASTING?
THE GLOBAL POSITIONING System's 24 satellites have already revolutionized navigation and mapping. Next, the GPS system may--indirectly--do the same for weather forecasting.
Since April, 1995, an eight-pound "bird" has been scooting around in low earth orbit, 450 miles up. It flies through the radio signals beaming down from the 12,500-mile-high GPS network. By measuring how the GPS signals are distorted as they pass through the upper atmosphere, this space sparrow makes it possible to calculate local variations in air temperature, pressure, and humidity. Integrating such data with regular measurements, including those from weather balloons that go pop before reaching 20 miles, could lead to around-the-clock forecasts of unprecedented accuracy, says Jay Fein, who serves as director of atmospheric sciences at the National Science Foundation.
Timely coverage of the whole earth "would require a constellation of 8 to 16 microsatellites," says Michael L. Exner, head of GPS meteorological research at the University Corp. for Atmospheric Research. Such a fleet, Exner adds, could be built and launched for less than $100 million.EDITED BY OTIS PORTReturn to top
BREATHING LIFE INTO ARTIFICIAL LUNGS
HEART PATIENTS WHO ARE waiting for a transplant can survive for months with artificial hearts. Surrogate lungs have proved harder to develop. But help for critically ill lung patients may be on the way.
Lyle F. Mockros, a professor of biomedical engineering at Northwestern University, and graduate student Keith Crook have devised an artificial lung that is the size of a portable CD player. It uses the heart's pumping action to disperse blood over the surface of porous polypropylene fibers. These mimic the functions of the vessels in healthy lungs, enabling the blood to shed toxic carbon dioxide and absorb oxygen. Mockros has successfully tested the system in pigs.
Other researchers have experimented with even smaller devices, designed to be inserted into a large vein. But these have had disappointing results so far--in part because they are so small and thus offer limited filtering and oxygen-absorption capacity. Further improvements to the Northwestern lung are under way. For example, the researchers are working with 3M to coat the device and its fibers with living cells. These will help prevent unwanted blood coagulation and rejection by the body's immune system.EDITED BY OTIS PORT By Neil GrossReturn to top
A WELDER YOU CAN ROLL UP
WELDING KITS CAN'T BE MUCH MORE PORTABLE THAN this: a roll of an aluminum-foil-like film and a match. If engineers or soldiers needed to make emergency repairs to a cracked axle, say, they could tear off a strip of foil, slip it in the break, then put a match to its edge. In the blink of an eye, the metal film would flare to a temperature of up to 3,000C and weld the crack.
Such welding foils recently earned U.S. patent No. 5,538,795 for Timothy P. Weihs, an assistant professor of materials science at Johns Hopkins University, and Troy W. Barbee Jr., a senior researcher at Lawrence Livermore National Laboratory. The concept is similar to the thermite process, patented in 1908, which triggers a high-temperature flare between aluminum and iron oxide powders--and was used to join the ends of railroad ties. But with today's technology, says Weihs, thin metal foils can be tailored from various reactive materials, such as aluminum and nickel, "to produce the precise heat-release rate and final temperature we want." As a result, surfaces can be joined without risk of heat damage to the bulk of the material.
Welding foils are now too costly to compete with traditional methods, admits Weihs. But once the technology is in mass production--and Livermore has a couple of license deals cooking--it might become a common industrial tool.EDITED BY OTIS PORTReturn to top