Sputnik 1 — the space age begins

A 58-cm silver sphere became the first artificial satellite; its beeps on radios worldwide started the space race.

The story

On the night of 4 October 1957 an R-7 rocket at Tyuratam in Kazakhstan — today's Baikonur — placed a polished sphere 58 cm across and 83.6 kg in mass into orbit. Sputnik 1 circled Earth every 96 minutes, transmitting its "beep-beep" on 20.005 and 40.002 MHz, and any amateur radio operator could hear it.

The orbit was an ellipse from 215 km at perigee to 939 km at apogee. The sphere itself was barely naked-eye even in sunlight, but the R-7 core stage that followed it round shone at first magnitude, and people across the world saw "the satellite" cross the dawn and dusk sky for the first time — most of them were looking at the rocket.

The American reaction became a phrase, the "Sputnik shock". Explorer 1 in January 1958, ARPA in February, NASA in July, then Apollo and the ancestor of the internet — the history this little sphere set in motion reaches far beyond space.

Sputnik itself transmitted for three weeks until its batteries died on 26 October, and burned up on re-entry on 4 January 1958. The first page of the space age was that short and that loud. The spacing of its pulses carried internal temperature and pressure, making it the first telemetry broadcast as well.

Why it matters

What Sputnik proved was not satellite technology but the rocket. An R-7 that could lift 83 kg to orbit was an intercontinental ballistic missile able to deliver a warhead across the world, and Washington understood that at once. The Cold War balance moved into the sky.

There was a scientific legacy too. Changes in the radio signal through the ionosphere became early ionospheric data; orbital decay gave the first measurements of upper-atmosphere density; and a Johns Hopkins experiment that located the satellite from the Doppler shift at a ground receiver led directly to satellite navigation — Transit, the ancestor of GPS.

It also mattered that the launch was part of the International Geophysical Year (1957–58). Both the US and the USSR had promised a satellite for that year; the Soviets delivered first. 4 October still opens World Space Week.

How to watch

Sputnik was gone by January 1958, so there is no trajectory to replay. Its descendants can be seen instead: switch on satellites in the sky view and the ISS and the bright satellites now crossing your location are drawn from real orbital elements — slow points crossing the dawn and dusk sky just as Sputnik's rocket did.

The conditions of 1957 still apply. A satellite shines only in the hour or two after sunset or before sunrise, when the observer is in darkness but the satellite is still in sunlight; in the middle of the night it sits in Earth's shadow and is invisible.

Sputnik's beeps survive as recordings in museums and NASA's archives; at the time the 40 MHz signal could be picked up on a short-wave radio.

Background

America's first attempt, Vanguard TV-3, rose a metre off the pad on 6 December 1957 and exploded — "Kaputnik" in the press. Success came with Explorer 1 from von Braun's team on 31 January 1958, the satellite that discovered the Van Allen belts.

Sputnik 2 followed a month later, on 3 November, carrying the dog Laika — the first living creature in orbit, with no means of return; she died of overheating within hours. It was the starting point of the crewed programme that led to Gagarin three and a half years later.

The R-7 family still flies today as the Soyuz, carrying crews and cargo to the ISS — a 1957 design in service for almost seventy years.

Sputnik 1 was not the satellite originally planned. The Soviet Union was preparing a heavy scientific satellite (later Sputnik 3), but as development slipped, an 83.6 kg simple sphere was built in a month and launched first to beat the United States into orbit. It carried four antennas, a transmitter and batteries — no scientific instruments. Transmissions ended after three weeks when the batteries died, and the satellite re-entered and burned up on 4 January 1958 after 1,440 orbits of the Earth.

FAQ

How big was Sputnik?

A sphere 58 cm across and 83.6 kg in mass, with four antennas 2.4–2.9 m long.

Could it be seen with the naked eye?

The satellite itself was barely visible; the bright point people saw was the R-7 core stage orbiting behind it.

How long did it transmit?

Three weeks, until 26 October; it re-entered and burned up on 4 January 1958.

Why was the US so alarmed?

Because the R-7 that launched it was an intercontinental missile capable of carrying a nuclear warhead; NASA and ARPA were the response.

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Times and figures are approximate — verify with official sources when planning travel. Simulation uses J2000 mean elements.