Discovery
| Parameter | Value |
|---|---|
| Launch date | October 4, 1957, 19:28 UTC |
| Launch site | Baikonur Cosmodrome, Kazakhstan |
| Launch vehicle | R-7 Semiorka (converted ICBM, 267 t at liftoff) |
| Designer | Sergei Korolev (identity kept secret until 1966) |
| Mass | 83.6 kg |
| Diameter | 58 cm |
| Frequencies | 20.005 MHz and 40.002 MHz |
| Orbital lifetime | 92 days (re-entry January 4, 1958) |
Technical Explanation
1. Orbit insertion via ICBM — The R-7 was a two-stage intercontinental ballistic missile originally designed to carry a 5.4-tonne nuclear warhead. Its combined thrust of 3,900 kN (20 RD-107/108 engines burning kerosene + liquid oxygen) vastly exceeded the requirements for an 83.6 kg satellite. Total Δv ≈ 9.5 km/s, sufficient to reach orbital velocity.
2. Elliptical orbit — Perigee 228 km, apogee 947 km, inclination 65.1°, period 96.2 minutes. With each orbit, Sputnik passed over a different swath of the Earth (the planet rotates 15°/h beneath it). Atmospheric drag at perigee gradually slowed the satellite.
3. Radio transmission — Two transmitters powered by 3 silver-zinc batteries (1 kWh total) broadcast a 0.3 W signal alternating on two frequencies. The "beep-beep" pattern (0.3 s on, 0.3 s off) allowed any ground station to confirm the satellite's passage. Transmission duration: 21 days (batteries exhausted October 26).
4. Thermal design — The sphere was pressurized to 1.3 atm with nitrogen. An internal fan distributed heat. If the temperature exceeded 50 °C or dropped below 0 °C, the beep cadence changed — a rudimentary telemetry system.
Why It Worked
Korolev chose pragmatism: rather than waiting for the complex scientific satellite (the future Sputnik 3), he launched a simple object — a radio-emitting sphere with no instruments — maximizing the probability of success on the first attempt. The R-7 was massively oversized for the payload, providing comfortable margins. The choice of amateur-band frequencies ensured the entire world could independently verify the achievement.
The geopolitical impact was immediate and disproportionate. If the R-7 could place an object in orbit, it could deliver a nuclear warhead to any city on Earth. The "Sputnik shock" triggered a cascade of American institutional responses that reshaped the Cold War landscape.
Causal Chain
Soviet R-7 ICBM program → Korolev proposes a satellite → Sputnik 1 in orbit (October 1957) → Sputnik shock in the USA → DARPA created (February 1958) → NASA created (July 1958) → ARPANET (1969) → Apollo 11 on the Moon (1969) → GPS, telecommunications, Earth observation → 10,000+ active satellites (2025)
Anecdote
Korolev could not be publicly named — he was referred to as "the Chief Designer" in the Soviet press. His identity was only revealed upon his death in 1966. On launch day, Khrushchev was so indifferent that he did not mention Sputnik in his evening address. It was only after witnessing the worldwide reaction that he grasped the propaganda value of the achievement.
Sources
References verified during the August 2026 fact-checking audit: these are the pages
against which this bulletin's claims were checked.