Solar craft

From environment-friendly cars, researchers move on to an environment-friendly aircraft, which derives all its energy from sunlight.

Developed by a team of scientists from AcroVironment, an engineering company based in Simi Valley, California, this new version of Pathfinder, a 18 1 -kg acroplane, is to begin test flights soon (Nature, Vol 375, No 6528).

AcroVironment hopes to get this unmanned aircraft to attain heights of 20,000 mietres and touch speeds of 160 knn an hour.

Lightweight silicon solar cell arrays laid out on the 74-square metre wings make the new version twice as efficient as its predecessor.