<p>A replica of Sputnik 1, the first artificial satellite to go into Earth orbit, on display in the Smithsonian Air and Space Museum in Washington, D.C.
</p><p>On December 17, 1954, rocket engineer Sergei Korolev proposed that the Soviet Union develo an artificial satellite.  Korolev knew that several Western scientists were already working toward this goal.  On July 29, 1955, U.S. President Dwight D. Eisenhower said the United States would launch an artificial satellite during the International Geophysical Year (IGY) of 1958.  The Council of Ministers (the heads of all Soviet executive-branch agencies) approved the plan on January 30, 1956.
</p><p>A host of scientific experiments were to have flown aboard the satellite.  But poor coordination meant that many of these were too big to fit, or did not fit well with the other science packages.  Some simply failed to work altogether.  Furthermore, the R-7 rocket that was intended to lift the satellite into orbit was not working well, and could not lift a heavy satellite.
</p><p>On February 15, 1957, the Council of Ministers approved a new satellite design -- a simple radio transmitter.  
</p><p>Sputnik was designed by M.S. Khomyakov. A 23-inch sphere made of aluminium-magnesium-titanium alloy 2 mm thick.  A 1 mm thick heat shield made of the same alloy covered the sphere.  Two antennas (bent into a V-shape) designed by the Antenna Laboratory, about 7.9 and 9.5 feet in length, were attached to the sphere.  Three silver-zinc batteries formed the power supply.  Two powered the radio  and one powered an internal fan. A one-watt radio broadcast beeps on two frequencies.  Depending on the temperature and pressure, the beeps transmitted by the radio varied in length.  Sputnik was filled with dry nitrogren, and a fan turned on to keep the radio cool if the temperature rose about 97 degrees F.  If the temperature rose above 120 degrees F, or if it fell below 68 degrees F, the fan was turned off.  A second thermal switch changed the length of the radio beeps if this happened.  If the pressure inside the satellite fell below 5 psi, a barometric switch changed the length of the radio beeps on the second frequency.
</p><p>The Sputnik rocket was launched on October 4, 1957.  Its orbit was just 139 miles, and it orbited the Earth every 96.2 minutes.
</p>
Sputnik 1 remained in orbit until 4 January 1958, when it re-entered the atmosphere.
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/23165290@N00">Tim Evanson</a> from Cleveland Heights, Ohio, USA
CC BY-SA 2.0
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/timevanson/7275640706/">Sputnik1 a - Smithsonian Air and Space Museum - 2012-05-15</a>