October 4, 1957: Sputnik beeps out a cheerful declaration of survival in the harshest of environments as the first artificial satellite to successfully orbit the Earth.
A 1957 newsreel cartoon introduced Americans to the first artificial satellite. Watch the entire reel here.
On October 5, 1957 at 1:28am local time, an R-7 intercontinental ballistic missile blasted out of Baikonur Cosmodrome. Just 295 seconds later, the engines cut out after pulling 228 kilometers (142 miles) away from the planet. Pneumatic locks unlatched, dropping fairings off the nosecone to reveal an antenna spike. A pushcone on the bulkhead activated, shoving a small sphere ahead of the spacecraft. Trailing four whiskery antenna, Sputnik-1 was officially in orbit.
Unleashed by the Soviet Union, Sputnik-1 was the first artificial satellite for our tiny planet. At 82 kilograms (183 pounds), the 58-centimeter (23-inch) diameter sphere packed a ridiculous amount of science into a beach ball-sized package.
Interior view of the Sputnik satellite. From left to right: radio transmitting in 20 and 40 MHz, silver-zinc batteries, and ventilation fan encased within an aluminum-alloy shell. Image credit: NASA
Along with being a proof-of-concept that a satellite travelling fast enough could enter perpetual free-fall to orbit our planet, it also investigated the upper atmosphere and ionosphere.
The satellite transmitted a steady beep for three weeks; everyone from government agencies to ham radio operators listened to the satellite. Sputnik’s steady beep-beep-beep provided data on how radio signals propagate through the ionosphere. Even after the batteries died, ground telescopes tracked the inactive satellite’s decaying orbit and learned about high altitude atmospheric density.
October 7, 1957: G.P. Pearson [front] and Herbert V. Griffiths [back] listen to Sputnik radio signals at the British Broadcasting Corporation’s measurement and receiving station at Tatsfield, Kent. Image credit: AP
Sputnik-1 was also the first space-based study on the consequences of space junk impacts. The aluminum alloy sphere was pressurized with nitrogen. If something whacked the sphere hard enough to penetrate the shell, the loss in pressure would show up in the transmitted temperature data. No events were reported.
A technician checks on the satellite prior to launch. Image credit: NASA/A. Siddiqi
The Sputnik satellite has most recently been honoured as a noteworthy explorer with a namesake on Pluto. The unofficially-named Sputnik Planum is an oddly smooth icy landform within the dwarf planet’s heart Tombaugh Regio.