Space missions rely on Solar Energy. Vanguard 1 was the first satellite to generate power through solar cells

In 1958, Vanguard 1 satellite utilized a small one-watt panel to operate its radios. Afterward, Vanguard II, Explorer III, and Sputnik-3 were launched that same year, all equipped with photovoltaic technology. Later, in 1964, NASA launched the first fully solar-powered spacecraft, Nimbus, which had a 470-watt solar array. In 1966, NASA deployed the world's first Orbiting Astronomical Observatory, powered by a one-kilowatt array.