Sputnik 1

Specifications Prime contractor Korolov's design bureau (NII-88/Podlipki) Platform   Mass at launch 83.6 kg Mass in orbit   Basic shape: Sphere Dimension: 58 cm diameter with four antennas that were 2.4 to 2.9 m long Stabilization   DC power   Frequencies: 20.005 & 40.002 MHz

Exploded view of the Sputnik 1 satellite

End of life

Description:

In 1885 Konstantin Tsiolkovsky first described in his book, Dreams of Earth and Sky, how such a satellite could be launched into a low altitude orbit. It was the first in a series of four satellites as part of the Sputnik program of the former Soviet Union and was planned as a contribution to the International Geophysical Year (1957-1958). Three of these satellites (Sputnik 1, 2, and 3) reached Earth orbit.

The Sputnik 1 satellite was a 58.0 cm-diameter aluminum sphere that carried four whip-like antennas that were 2.4-2.9 m long. The antennas looked like long "whiskers" pointing to one side. The spacecraft obtained data pertaining to the density of the upper layers of the atmosphere and the propagation of radio signals in the ionosphere. The instruments and electric power sources were housed in a sealed capsule and included transmitters operated at 20.005 and 40.002 MHz (about 15 and 7.5 m in wavelength), the emissions taking place in alternating groups of 0.3 s in duration. The downlink telemetry included data on temperatures inside and on the surface of the sphere.

Since the sphere was filled with nitrogen under pressure, Sputnik 1 provided the first opportunity for meteoroid detection (no such events were reported), since losses in internal pressure due to meteoroid penetration of the outer surface would have been evident in the temperature data. The satellite transmitters operated until 25 Oct, when the on-board chemical batteries ran out, and were monitored with intense interest around the world. The orbit of the then inactive satellite was later observed optically to decay 92 days after launch (January 4, 1958) after having completed about 1400 orbits of the Earth over a cumulative distance traveled of 70 million kilometers. The orbital apogee declined from 947 km after launch to 600 km by Dec. 9th.

The Sputnik 1 rocket booster also reached Earth orbit and was visible from the ground at night as a first magnitude object, while the small but highly polished sphere barely visible at sixth magnitude more difficult to follow optically.

Sputnik origins:

• The first Soviet satellite to be launched was the 1-tonne "Object D". But delays that occured during 1956 prompted Korolev to ordered, on 25 November 1956, a young engineer at OKB-1, Nikolay Kutyrkin, to begin designing a new smaller satellite. Another young man, Georgiy Grechko (a twenty-six-year-old engineer who would fly into space from the same site eighteen years later), set about calculating preliminary ballistics on the launch. On January 5, 1957, Korolev asked for permission to launch two small satellites, each with a mass of forty to fifty kilograms, during the period of April-June 1957, that is immediately prior to the beginning of the International Geophysical Year. Each satellite would orbit Earth at attitudes of 225 to 500 kilometers and contain a simple shortwave transmitter with a power source sufficient for ten days of operation.
• By January 25, 1957, Korolev had approved the initial design details of the satellite officially designated the Simple Satellite No. 1 (PS-1). On February 15, the USSR Council of Ministers formally signed a decree (no. 171-835s) titled "On Measures to Carry out in the International Geophysical Year," agreeing to the new proposal. The two new satellites, PS-1 and PS-2, would weigh approximately 100 kilograms and be launched in April-May 1957, after one or two fully successful R-7 ICBM launches. Meanwhile, the Object D launch was pushed back to April 1958. In the summer, Korolev, Glushko, and the other chief designers had informally targeted the satellite launch for the 100th anniversary of Tsiolkovskiy's birth on September 17th, but achieving this date proved increasingly unrealistic.

Mission details:

• 1 Oct 1957: R-7 rocket complete with PS-1 satellite rolled out to the launch pad
• 4 Oct 1957: World first artificial satellite Sputnik' launched from the Baikonur Cosmodrome by Sputnik (R-7) rocket into 215 x 939 kilometre orbit at 65.1 degrees inclination
• 12 Oct 1957: Following the success of Sputnik, Soviet leader Nikita Khruschev instructs Korolyov team to produce a more-impressive mission to mark the 40th anniversary of the Soviet Revolution - work begins on a satellite which will carry a dog, using the backup hardware for PS-1 as a starting point.
• 25 Oct 1957: Radio transmissions from Sputnik (PS-1) cease when its electrical batteries are exhausted.
• 04 Jan 1958: Sputnik (PS-1) enters the Earth atmosphere as a result of natural decay of the orbit through air drag, and is destroyed by frictional heating.