March 1958: The first PVS in orbit [Numbers Don't Lie]

SIXTY YEARS AGO THIS MONTH, a rocket lifted off from Cape Canaveral bearing the Vanguard 1 satellite, a small, 1.46-kilogram aluminum sphere that was the first to use photovoltaic cells in orbit. . As a safeguard, one of the satellite's two transmitters drew power from mercury batteries, but they failed after just three months. The six monocrystalline silicon cells, each roughly 5 centimeters on a side and delivering a total of just 1 watt, kept on powering a beacon transmitter for 14 months, until May 1964.