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Sputnik 1
October 4, 1957· Invention or discovery· Transport & space
Well documentedSolid records, physical evidence or scientific consensus.
The first artificial satellite, a Soviet metal sphere whose radio beeps from orbit started the Space Race.
See it on the Technology & Medicine map →How it works
On October 4, 1957, a Soviet R-7 rocket, designed under Sergei Korolev as a nuclear missile, put Sputnik 1 into orbit from Tyuratam (now Baikonur), Kazakhstan. The polished aluminium ball was 58 cm wide, weighed 83.6 kg and carried two radio transmitters and four antennas. It circled Earth every 96 minutes, beeped for 21 days until its batteries died, and burned up on re-entry in January 1958.
Why it mattered
It showed Soviet rockets could reach anywhere on Earth, shocking the US into creating NASA and ARPA, pouring money into science education, and racing to the Moon.
How we know
Soviet announcements, radio recordings of its signal made around the world, optical tracking by volunteer observers, and Soviet design records released after 1991.
Still unknown or debated
Some historians argue Eisenhower quietly welcomed Sputnik: by flying over every country unopposed, it set the precedent that US spy satellites could do the same.
Connections (4)
▸Radio carried the beeps of Sputnik 1Well documented
The connection
Sputnik carried two radio transmitters broadcasting a steady beep on about 20 and 40 megahertz, frequencies chosen so ordinary amateur radio operators worldwide could hear it. The signal proved the satellite was really in orbit and alarmed Western publics. Changes in the signal also revealed details of the upper atmosphere.
When and how
Launched from Tyuratam (now Baikonur), Kazakhstan, on October 4, 1957; the beeps were heard for 21 days, until the batteries ran down.
How we know
Radio amateurs, observatories and broadcasters around the world recorded the beeps, and the recordings survive; NBC played them on air.
Debates and open questions
Little is in doubt. Historians do debate how far Soviet leaders, whose newspaper Pravda first gave it a short report, expected its huge propaganda effect.
▸Sputnik 1 prompted the agency that built ARPANETWell documented
The connection
Sputnik shocked Washington into creating the Advanced Research Projects Agency (ARPA) in February 1958, so the US would not be surprised by technology again. Space work soon moved to NASA, and ARPA turned to other fields, including computing; its computer office, set up in 1962 under J. C. R. Licklider, funded the network that became ARPANET.
When and how
ARPA founded in Washington in February 1958 under President Eisenhower; Licklider's office from 1962; Bob Taylor won ARPANET funding in 1966.
How we know
ARPA's founding papers cite the post-Sputnik need; Taylor and Larry Roberts described the office's role in oral histories, and official ARPA histories agree.
Debates and open questions
How much credit Sputnik deserves is a matter of emphasis: ARPA's computing office also grew from military command-and-control needs and Licklider's own vision of interactive computing.
▸Sputnik 1 was followed by Yuri Gagarin, first human in spaceWell documented
The connection
Sputnik's R-7 rocket, the world's first intercontinental ballistic missile, was adapted to launch Vostok 1. A month after Sputnik, Sputnik 2 carried the dog Laika, who died in orbit; later flights returned dogs alive and tested dummy capsules before risking a person. Gagarin flew three and a half years after Sputnik.
When and how
Both launched from Tyuratam (Baikonur), Kazakhstan, by Sergei Korolev's design bureau: Sputnik in October 1957, Vostok 1 in April 1961.
How we know
Soviet launch records, declassified after 1991, document the shared R-7 rocket family and Korolev's leadership of both programs.
Debates and open questions
Rumours of secret cosmonaut deaths before Gagarin circulated for decades; historians found no evidence, though trainee Valentin Bondarenko died in a ground training fire weeks before the flight.
▸Sputnik 1 led, via satellite tracking, to GPS satellite navigationWell documented
The connection
Days after Sputnik's launch, physicists William Guier and George Weiffenbach noticed its radio pitch shifted as it passed overhead, the Doppler effect, and could calculate its whole orbit from that. Their colleague Frank McClure reversed the idea: if you know a satellite's orbit, you can find your own position. That became the Navy's Transit system, then inspired GPS.
When and how
Johns Hopkins Applied Physics Laboratory in Maryland, October 1957 to 1958; Transit guided Navy submarines from 1964, and GPS was approved in 1973.
How we know
The laboratory's histories and Guier and Weiffenbach's own published account document the chain; Transit was the first working satellite navigation system.
Debates and open questions
GPS also drew on the Navy's Timation clock satellites and the Air Force's Project 621B; how to divide credit among them is still argued.