Lonnie Johnson

Lonnie Johnson was born in Mobile, Alabama, in 1949, one of six children of a driver who had served in the Second World War and a nurse\'s aide. He took things apart from the start: his sister\'s doll for its eyes, a go-kart he powered with a lawnmower engine, and a batch of rocket fuel he cooked on the stove until it set the kitchen on fire. Neighbourhood children called him the Professor. His high school was all Black, and a test told him he had little aptitude for engineering.

In 1968 he took a compressed-air robot he had built from junkyard parts, which he called Linex, to a science fair at the University of Alabama, the only Black student entered. He won first prize. The university did not congratulate him.

He studied mechanical and nuclear engineering at Tuskegee, joined the Air Force, and in 1979 went to NASA\'s Jet Propulsion Laboratory, where he worked on the power system of the Galileo probe to Jupiter. At home in 1982 he was experimenting with a heat pump that used water instead of freon. He connected a nozzle to the bathroom tap and a powerful jet shot across the room. It took seven years to find a toy company willing to make it. The Super Soaker went on sale in 1990 and became one of the best-selling toys ever made.

He has put the royalties into his own laboratories in Atlanta, working on solid-state batteries and an engine that turns heat directly into electricity.