First use of solar power in space

On 17/03/1958, the United States launched Vanguard 1 from Cape Canaveral, Florida, aboard a Vanguard launch vehicle, marking the first use of solar energy to power a satellite in space. Developed under the Vanguard program, the small, spherical spacecraft was designed to test launch capabilities and study the effects of the space environment on a satellite in orbit. It followed earlier U.S. satellite efforts and became one of the earliest artificial satellites placed into Earth orbit. Vanguard 1 carried six small solar cells mounted on its surface, which powered a radio transmitter and demonstrated that solar energy could sustain satellite operations for extended periods. In addition to its solar-powered system, the satellite included batteries for backup. The mission also contributed to scientific research, including measurements of Earth’s shape. Data from Vanguard 1 helped scientists determine that Earth is slightly pear-shaped, with a slight bulge in the southern hemisphere. The satellite transmitted signals for several years, far exceeding the operational life of earlier satellites, and remained in orbit long after communications ceased. Vanguard 1 is still in orbit today, making it one of the oldest human-made objects in space. Its success demonstrated the practicality of solar power for spacecraft, which later became a standard energy source for satellites and deep-space missions.