Sputnik 1 — the space age begins
On 4 October 1957 Sputnik 1, a metal ball 58 cm across, became the first human-made object to orbit the Earth. Its ‘beep-beep’ signal was picked up on radios around the world, and the space race between the United States and the Soviet Union began in earnest.
The story
On the night of 4 October 1957 a Soviet R-7 rocket lifted off from the Tyuratam launch site in what is now Kazakhstan, today known as Baikonur. At the tip of the rocket sat a shiny metal ball 58 centimetres across and weighing 83.6 kilograms. When the ball reached orbit it became the first artificial satellite, the first human-made object to circle the Earth. Its name was Sputnik 1.
Sputnik 1 went around the Earth about once every 96 minutes. Its orbit was not a round circle but a stretched oval, so its height ranged from about 215 km at the lowest point to about 939 km at the highest. The satellite kept sending short ‘beep-beep’ signals on two radio frequencies, and amateur radio operators could hear the sound directly on radios at home.
Many people believed they had seen ‘the satellite’ with their own eyes in the dawn and evening sky. In fact the bright point most of them saw was not the satellite but the large core stage of the R-7 rocket, which had reached orbit along with it. The small ball was so faint that it could barely be seen without a telescope even in sunlight, but the long rocket body shone much more brightly.
Sputnik 1 did not last long. It ran on batteries, and when they ran down about three weeks later, on 26 October, the signal stopped. It went on circling the Earth, dropping slowly as the thin upper air dragged on it, until it fell into the atmosphere and burned up on 4 January 1958, after about 1,440 trips around the planet. Turning on satellites in the sky view reproduces today’s satellites crossing the sky as they circle the Earth.
Mission goals
What alarmed the world was not so much the satellite as the rocket that launched it. The R-7 that carried Sputnik had been built as an intercontinental ballistic missile, designed to fly nuclear weapons to other continents. If it could put an 83-kilogram ball into orbit, it could also send a nuclear warhead far across the ocean. The American government and public were deeply shaken, and the shock became known as the ‘Sputnik crisis’.
The shock soon led to action. The United States launched its first satellite, Explorer 1, in January 1958, and in February it created ARPA, a defence agency for advanced research. In July a law was passed setting up NASA to run the country’s space programme. Research funded by ARPA later led to a computer network that became one of the foundations of the internet.
Sputnik also left something for science. Changes in its radio signal as it passed through the electrically charged layer high above the Earth gave data for studying that layer, and the rate at which the satellite sank because of air drag revealed how dense the air was high up. Researchers at Johns Hopkins University also found a way to work out the satellite’s position from shifts in the pitch of its signal, and this led to Transit, an early satellite navigation system.
Mission chronology and background
Sputnik 1 was not the satellite originally planned. The Soviet Union had been preparing a heavy satellite packed with scientific instruments, which later flew as Sputnik 3. When that project fell behind, a much simpler satellite was built in a hurry so as to reach orbit before the United States. Inside it there was little more than a radio transmitter, batteries and a temperature control system, with four antennas sticking out from the outside.
A month later, on 3 November 1957, Sputnik 2 carried the dog Laika into orbit. Laika was the first animal to orbit the Earth, but there was no way to bring her back, and she died of overheating a few hours after launch. The first American attempt, Vanguard TV-3, rose only slightly off its launch pad on 6 December and exploded. The United States put up its first satellite, Explorer 1, on 31 January 1958, and it discovered the Van Allen belts, zones of radiation surrounding the Earth.
Descendants of the R-7 rocket that launched Sputnik are still flying. The Soyuz rocket belongs to the R-7 family and carries astronauts and cargo to the International Space Station, so a design that first flew in 1957 has been in use for almost seventy years. 4 October, the day Sputnik was launched, still marks the start of World Space Week.
Where to see it — sky and simulator
Sputnik 1 burned up in January 1958 and can no longer be seen. The many satellites that followed it, however, still cross the sky. Turning on satellites in the sky view draws the International Space Station (ISS) and other bright satellites from real orbital data. It reproduces glowing points moving slowly between the stars, just as people in 1957 watched Sputnik’s rocket.
Satellites cannot be seen at any time of night. They do not make their own light; they shine by reflecting sunlight. So they show up best in the hour or two after sunset or before sunrise, when the ground is dark but sunlight still reaches the satellite high above. In the middle of the night a satellite passes into Earth’s shadow and disappears. The conditions in 1957 were exactly the same.
Recordings of Sputnik’s ‘beep-beep’ survive and can still be heard today. The signal, at about 20 MHz, could be picked up on a short-wave radio at the time. The spacing of the beeps is also said to have carried information about the temperature and pressure inside the satellite. A simple repeating beep told the whole world that a new era had begun.
FAQ
How big was Sputnik 1?
It was a metal ball 58 cm across and weighing 83.6 kg, with four antennas 2.4 to 2.9 metres long.
Could it be seen with the naked eye?
The satellite itself was barely visible. The bright point most people saw was the body of the R-7 rocket orbiting along with it.
How long did it transmit?
For about three weeks, until its batteries ran down on 26 October. The satellite burned up in the atmosphere on 4 January 1958.
Why was the United States so alarmed?
Because the R-7 that launched it was a missile able to carry a nuclear warhead to another continent. ARPA and NASA were created in response.
Related
- Gagarin — first human in space
- Apollo 11 launch
- Hubble Space Telescope launch
- Earth — object index
- The Moon — object index
Times and figures are approximate — verify with official sources when planning travel. Simulation uses J2000 mean elements.