The First Artificial Satellite

On October 4, 1957 life as everyone knew it was to forever change. The Homo sapiens has become the first species to ever space fare by deploying the first object to orbit the Earth. It was called Sputnik, I and it was the first artificial satellite of the Blue Planet. Sputnik I was followed by Sputnik II and the first living being ever to reach space, the dog Laika. Needless to say, an entire constellation of satellites followed afterwards, pervading Earth’s orbit with manned-made objects, and changing the life of the earthlings in a multitude of ways. This paper summarizes the launches and features of the first two Soviet satellites Sputnik I and II, as well as of the first successfully launched American satellite Explorer I, focusing on some of the systems aboard each satellite.

Sputnik I was the first Soviet satellite to launch into space and the first manned made object to orbit Earth. It was launched from Baikonur Cosmodrome on October 4, 1957 atop the Old Number Seven rocket.[1] Sputnik I orbited the Earth for 92 days, had about 184 pounds, and it was a contribution to the International Geophysical Year (1957-1958). Its main mission was to successfully launch into space and orbit Earth as the first artificial satellite ever built and deployed by humans. Sputnik I was an aluminum sphere with a diameter of 58 centimeters and equipped with four whip-like antennas about 2.4 to 2.9 meters long, deployed at 35 degrees angles. [2] The sphere was filled with nitrogen under pressure. The power source was made of three silver-zinc batteries housed inside a sealed capsule, while a ventilator was used for thermal regulation. [3] Sputnik I also had a one-watt transmitter that was received by amateur radios on Earth. Its beeping signal first hit the United States in the evening of October 4, 1957. [4] The orbital parameters of Sputnik I were: periapsis – 215 km, apoapsis – 939 km, period – 96 minutes, inclination – 65 degrees and eccentricity 0.05. [5]

Sputnik I was not equipped with an attitude stabilization system of any kind. Its communications system transmitter had one-watt of power and its signals were of 0.4 seconds alternatively at forty and twenty megahertz wavelengths. The power system consisted of three silver-zinc batteries. The satellite had four whip antennas of 2.4 and 2.9 meters length. [6] Sputnik I was indeed the embodiment of simplicity. It did not even have a payload other than its own body, the aluminum sphere and the beeping radio. Sputnik I did not receive any commands from ground stations, being only equipped with a transmitter and not a receiver. The thermal control system, powered by the three batteries onboard, consisted of a fan, a dual thermal switch and a control thermal switch. [7] The thermal control system successfully operated as planned.

Sputnik I operated for 1,400 orbits of the Earth, a mission of three months. The first artificial satellite was able to communicate with the ground for about three weeks, the actual duration of the batteries supplying the transmitter with power. The limiting factor in its ability to communicate was of course the short life of the batteries. The main mission of Sputnik I was massively met because it successfully reached the orbit of Earth and it stayed there for three month, simply demonstrating that humans are able to launch objects into space. The launch of Sputnik I in 1957 opened a whole new world of adventure for humanity. It was the beginning of what turned out being known as the space age.

Notes

[1] Curtis, Anthony. Space Satellite Handbook, 3^rd edition. Gulf Publishing Houston, TX, 1994, 1.

[2] National Aeronautics and Space Administration. Sputnik 1. http://nssdc.gsfc.nasa.gov/nmc/masterCatalog.do?sc=1957-001B (accessed March 12, 2013), para. 3.

[3] Ibid, para. 4.

[4] Curtis, Anthony. Space Satellite Handbook, 3^rd edition. Gulf Publishing Houston, TX, 1994, 2.

[5] National Aeronautics and Space Administration. Sputnik 1 – Trajectory Details. http://nssdc.gsfc.nasa.gov/nmc/spacecraftOrbit.do?id=1957-001B (accessed March 12, 2013).

[6] Ibid, para. 4.

[7] Ibid, para. 3.

[8] Ibid, para. 4.