<Vanguard.

While efforts to commercialize the silicon solar cell faltered, the Army and Air Force saw the device as the ideal power source for a top-secret project - earth-orbiting satellites. But when the Navy was awarded the task of launching America's first satellite, it rejected solar cells as an untried technology and decided to use chemical batteries as the power source for its Vanguard satellite. The late Dr. Hans Ziegler, probably the world's foremost expert in satellite instrumentation in the late 1950s, strongly differed with the Navy. He argued that conventional batteries would run out of power in days, silencing millions of dollar worth of electronic equipment. In contrast, solar cells could power a satellite for years. Through an unrelenting crusade led by Dr. Ziegler to get the Navy to change its mind, the Navy finally relented and as a compromise, put a dual power system of chemical batteries and silicon solar cells on the Vanguard. Just as Ziegler predicted, the batteries failed after a week or so, but the silicon solar cells kept the Vanguard communicating with Earth for years.