Luna 10 (E-6S series) was an unmanne space mission of the Luna program, also called Lunik 10. The Luna 10 spacecraft was launched towards the Moon from an Earth orbiting platform on March 31, 1966. It was the first artificial satellite of the Moon (or another heavenly body, for that matter). The spacecraft entered lunar orbit on April 3, 1966 and completed its first orbit 3 hours later (on April 4, Moscow time). Scientific instruments included a gamma-ray spectrometer for energies between 0.3—3 MeV (50–500 pJ), a triaxial magnetometer, a meteorite detector, instruments for solar-plasma studies, and devices for measuring infrared emissions from the Moon and radiation conditions of the lunar environment. Gravitational studies were also conducted. The spacecraft played back to Earth The Internationale during the Twenty-third Congress of the Communist Party of the Soviet Union. Luna 10 was battery powered and operated for 460 lunar orbits and 219 active data transmissions before radio signals were discontinued on May 30, 1966.