Sputnik 1 - Design

Design

The chief constructor of Sputnik 1 at OKB-1 was M.S.Khomyakov. The satellite was a 585 mm (23 in) diameter sphere, assembled from two hemispheres which were hermetically sealed using o-rings and connected using 36 bolts, and had a mass of 83.6 kilograms (184 lb). The hemispheres, covered with a highly polished 1 mm-thick heat shield made of aluminium-magnesium-titanium AMG6T ("AMG" is an abbreviation for "aluminium-magnesium" and "T" stands for "titanium", the alloy contains 6% of magnesium and 0.2% of titanium) alloy, were 2 mm-thick. The satellite carried two pairs of antennas designed by the Antenna Laboratory of OKB-1 led by M.V.Krayushkin. Each antenna was made up of two whip-like parts: 2.4 and 2.9 meters (7.9 and 9.5 ft) in length, and had an almost spherical radiation pattern, so that the satellite beeps were transmitted with equal power in all directions; making reception of the transmitted signal independent of the satellite's rotation. The whip-like pairs of antennas resembled four long "whiskers" pointing to one side, at equal 35 degrees angles with the longitudinal axis of the satellite.

The power supply, with a mass of 51 kg (110 lb), was in the shape of an octagonal nut with the radio transmitter in its hole. It consisted of three silver-zinc batteries, developed at the All-Union Research Institute of Current Sources (VNIIT) under the leadership of N. S. Lidorenko. Two of them powered the radio transmitter and one powered the temperature regulation system. They were expected to fade out in two weeks, but ended up working for 22 days. The power supply was turned on automatically at the moment of the satellite's separation from the second stage of the rocket.

The satellite had a one-watt, 3.5 kg (7.7 lb) radio transmitting unit inside, developed by V. I. Lappo from NII-885, that worked on two frequencies, 20.005 and 40.002 MHz. Signals on the first frequency were transmitted in 0.3 sec pulses (under normal temperature and pressure conditions on-board), with pauses of the same duration filled by pulses on the second frequency. Analysis of the radio signals was used to gather information about the electron density of the ionosphere. Temperature and pressure were encoded in the duration of radio beeps, which additionally indicated that the satellite had not been punctured by a meteorite. A temperature regulation system contained a fan, a dual thermal switch, and a control thermal switch. If the temperature inside the satellite exceeded 36 °C (97 °F) the fan was turned on and when it fell below 20 °C (68 °F) the fan was turned off by the dual thermal switch. If the temperature exceeded 50 °C (122 °F) or fell below 0 °C (32 °F), another control thermal switch was activated, changing the duration of the radio signal pulses. Sputnik 1 was filled with dry nitrogen, pressurized to 1.3 atm. For the pressure control the satellite had a barometric switch, activated when the pressure inside the satellite fell below 0.35 kg/cm2 (5.0 psi), changing the duration of radio signal impulse.

While attached to the rocket, Sputnik 1 was protected by a cone-shaped payload fairing, with a height of 80 cm (31.5 in) and an aperture of 48 degrees. The fairing separated from both Sputnik 1 and the rocket at the same time when the satellite was ejected. Tests of the satellite were conducted at OKB-1 under the leadership of O. G. Ivanovsky.