Sputnik 3 was an automatic scientific laboratory spacecraft. The scientific instrumentation (twelve instruments) provided data on pressure and composition of the upper atmosphere, concentration of charged particles, photons in cosmic rays, heavy nuclei in cosmic rays, magnetic and electrostatic fields, and meteoric particles. The outer radiation belts of the Earth were detected during the flight. The spacecraft remained in orbit until April 6, 1960. It was the largest satellite ever flown to that point by far, with a mass that was more than twice as much as the 5 previously flown satellites combined. The objective was to characterize the geophysics and space physics environment from orbit, including the newly discovered radiation belts. It was overseen by the Soviet Academy of Sciences.
Spacecraft and Subsystems
Sputnik 3 had a mass of 1327 kg. It was conically-shaped and was 3.57 meters long with a base diameter of 1.73 meters. It was powered by silver-zinc batteries and solar cells. Communication was via the Tral telemetry system utilizing a 20.005 MHz transmitter. Data was transmitted on a 48-channel commutated PAM system on an interrogated transmitter at 66 MHz. The spacecraft carried a tape recorder that unfortunately failed. There was no attitude control. The instrumentation and other equipment were held inside a pressurized compartment, which comprised most of the interior of the spacecraft. The scientific instrument payload included a magnetometer, solar corpuscular radiation detectors, magnetic and ionization pressure manometers, ion traps, electrostatic fluxmeter, radio frequency mass spectrometer, cosmic ray heavy nuclei detector, primary cosmic ray monitor, and micrometeorite detectors. Radio propagation investigations were also done using the transmitters.
Sputnik 3 launched on 15 May 1958 at 7:12 UT into a 217 x 1864 km Earth orbit with an inclination of 65 degrees and a period of 106 minutes. With the failed tape recorder, the spacecraft could only send data back to Earth in real time, so the only areas it could study where those in range of Soviet tracking stations, i.e. over Soviet territory. Communications were lost on 3 June 1958. The satellite reentered the Earth's atmosphere and burned up on 6 April 1960 after almost 2 years in orbit.