Engineering Topic #1: Sputnik 1

Wikipedia

This is simply an idea which I'm going to throw out there. Similar to how some of the other fora have 'album of the week' or 'film of the week', I thought how it might be an idea to throw up an engineering topic of the week. I'm straying away from the idea of just putting accomplishments up since disasters sometimes can be informative, although obviously unfortunate.

If you wish to suggest a possible topic, do so on this thread for the time being. If this thread doesn't fly, so be it.

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So to get the ball rolling, the first topic is the very first spacecraft launched into orbit around this planet. To avoid any crossover between this and the Space/Astronomy people, I'm concentrating on the design

Wikipedia wrote:

Introduction

Sputnik 1 was the first artificial satellite to be put into geocentric orbit. Launched by the Soviet Union on October 4, 1957, it was the first of a series of satellites collectively known as the Sputnik program.

The satellite helped to identify the density of high atmospheric layers through measurement of its orbital change and provided data on radio-signal distribution in the ionosphere. Because the satellite's body was filled with pressurized nitrogen, Sputnik 1 also provided the first opportunity for meteorite detection, as a loss of internal pressure due to meteoroid penetration of the outer surface would have been evident in the temperature data sent back to Earth. The unanticipated announcement of Sputnik 1's success precipitated the Sputnik crisis in the United States and ignited the so-called Space Race within the Cold War.

Sputnik-1 was set in motion during the International Geophysical Year from Site No.1 at the 5th Tyuratam range in Kazakh SSR (now at the Baikonur Cosmodrome). The satellite traveled at 29,000 kilometers (18,000 mi) per hour and emitted radio signals at 20.005 and 40.002 MHz[1] which were monitored by amateur radio operators throughout the world. The signals continued for 22 days until the transmitter batteries ran out on October 26, 1957.[2] Sputnik 1 burned up as it fell from orbit upon reentering Earth's atmosphere, after traveling about 60 million km (37 million miles) and spending 6 months in orbit.

Design

The chief constructor of Sputnik 1 at OKB-1 was M.S.Khomyakov.[25] 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.[26] The hemispheres, covered with a highly polished 1mm-thick heat shield[27] 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[28]) alloy, were 2mm-thick.[29] The satellite carried two antennas designed by the Antenna Laboratory of OKB-1 led by M.V.Krayushkin.[9] Each antenna was made up of two whip-like parts: 2.4 and 2.9 meters (7.9 and 9.5 ft) in length,[30] and had an almost spherical radiation pattern,[31] 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.[32]

The power supply, with a mass of 51 kg,[33] was in the shape of an octahedral nut with the radio transmitter in its hole.[34] 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.[33] 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.[32]

The satellite had a one-watt, 3.5 kg[18] radio transmitting unit inside, developed by V. I. Lappo from NII-885,[32] that worked on two frequences, 20.005 and 40.002 MHz. Signals on the first frequency were transmitted in 0.3 sec pulses (under normal temperature and pressure conditions onboard), with pauses of the same duration filled by pulses on the second frequency.[35] 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.[32] If the temperature inside the satellite exceeded 36 °C the fan was turned on and when it fell below 20 °C the fan was turned off by the dual thermal switch.[31] If the temperature exceeded 50 °C or fell below 0 °C, another control thermal switch was activated, changing the duration of the of radio signal pulses.[32] Sputnik 1 was filled with dry nitrogen, pressurized to 1.3 atm.[36] For the pressure control the satellite had a barometric switch, activated when the pressure inside the satellite fell below 0.35 kg/cm² (approx. 0.34 atm), changing the duration of radio signal impulse.[36]

While attached to the rocket, Sputnik 1 was protected by a cone-shaped payload fairing, with a height of 80 cm and an aperture of 48 degrees.[18] The fairing separated from both Sputnik 1 and the rocket at the same time when the satellite was ejected.[32] Tests of the satellite were conducted at OKB-1 under the leadership of O. G. Ivanovsky.[25] Sputnik 1 was launched by an R-7 rocket on October 4, 1957. It burned up upon re-entry on January 4, 1958.

http://en.wikipedia.org/wiki/Sputnik_1
http://inventors.about.com/library/inventors/blsatellite.htm
http://www.nasa.gov/externalflash/SpaceAge/index.html

Turbulent Bill

A great piece of engineering, especially considering it was the first of its kind. I really like the idea of the radio signals being received by ham operators, I'm sure it gave a real sense of connection with the mission. NASA obviously webcasts lots of their mission data now, but its all very sanitised and 'on message'.