LOOK NO FUEL
IN THE first demonstration of sustained 鈥渂eamed-energy propulsion鈥� an unfuelled radio-controlled aircraft took to the air inside a NASA hangar in Alabama last week. The 300-gram balsa-wood-and-composite plane was powered by a laser from the ground, beaming energy to photovoltaic cells on the plane鈥檚 underside. This produced electricity to drive a propeller on the 1.5-metre wingspan plane.
Robert Burdine, one of the engineers behind the project at NASA鈥檚 propulsion research centre in Huntsville, described the feat as 鈥渁 ground-breaking development for aviation鈥�. It may lead to ultralight laser-powered drones that circle cities indefinitely, beaming cellphone, TV or internet traffic to homes. Although lasers have powered tiny aircraft before (51动漫, 15 June 2002, p 20) these craft relied on 鈥渙ne-shot鈥� bursts of propulsion produced by vaporising material, rather than the sustained power achieved last week.
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CUT-PRICE CONNECTIONS
CELLPHONE base stations typically need different boxes of transceiver hardware to handle different call standards such as 3G and GSM. But this doubling-up of hardware makes base stations expensive to build, particularly in rural areas where subscriber numbers are typically low.
Now Vanu Corporation of Cambridge, Massachusetts, has a simple answer. It says network operators should instead use general-purpose transceiver hardware 鈥� a Linux-based computer with digital signal processing capability 鈥� and bolt on software that can handle any standards. The idea appears to work: a trial of Vanu鈥檚 鈥渟oftware basestation鈥� is up and running for the Mid-Tex Cellular network in the rural Texas towns of De Leon and Gorman. When 4G services are introduced, the network will simply download new Vanu software, rather than adding more pricey hardware.
CORNY RECORDINGS
CD could soon stand for 鈥渃orn disc鈥�. In December, Sanyo Electric of Tokyo is set to launch the first optical discs made from plastics derived from corn cobs. The discs are made from polylactic acid from corn kernels, and are just as strong and durable as conventional plastic CDs and DVDs. But why bother? Unlike conventional discs, the corn cob discs don鈥檛 release dioxins when incinerated and can easily be broken down by bacteria into harmless materials.
