By Dr. Gary L Deel, Ph.D., J.D.
Faculty Director, School of Business, American Military University
This is the first article in a three-part series on the earliest satellites launched by the Soviet Union and the United States
The post-World War II Cold War was a dark and frightening time in world history, and the earliest space launches marked some of the tensest moments in this international standoff. Simultaneously, the “Space Race” brought with it exciting and terrifying developments as the Soviet Union (USSR) and the U.S. pushed each other to gain and maintain control of the ultimate high ground.
Get started on your Space Studies Degree at American Military University.
Compared to modern spacecraft, the earliest satellites were primitive, but at the time they were breakthroughs in pioneering human spacefaring capability.
Sputnik I, the First Soviet Satellite
On October 4, 1957, the Soviet Roscosmos space agency launched the first satellite into orbit around the Earth, Sputnik I, Russian for “fellow traveler.” But this benign name did little to calm American fears of possible Soviet aggression, especially a nuclear attack launched from space.
The Soviets used an R-7 Semyorka rocket to launch Sputnik I into orbit. The R-7 was originally designed to be an intercontinental ballistic missile (ICBM), but was repurposed for the Sputnik flights. The first test flights of the R-7 in May 1957 failed for a variety of reasons. The rocket wasn’t successfully launched until August of that year, just two months before Sputnik’s debut.
Sputnik’s Mission Was to Take Scientific Data Measurements and Radio Them to Earth
The primary mission of Sputnik I — beyond simply demonstrating the Soviet Union’s ability to successfully launch a satellite into orbit — was to take basic scientific data measurements and radio them back to Earth. Specifically, Sputnik I measured its interior pressure and temperature. Its radio transmissions were used to analyze the strength of the ionosphere in its orbit.
Sputnik I consisted of a metallic ball-shaped hull, with four jutting antennas between eight and 10 feet long that allowed the satellite to communicate well with ground stations regardless of its flight orientation. The beachball-size satellite was about 23 inches in diameter and weighed about 184 lbs. Three notable components of the Sputnik I design were:
- The polished heat shield surrounding the ball portion was made primarily of an aluminum-magnesium-titanium alloy.
- The antennas, which had an almost spherical radiation pattern, permitted the satellite to emit strong signals in all directions.
- The batteries inside the ball portion that powered Sputnik I were made of silver and zinc.
Sputnik I had no attitude control system. As such, it would have been free to tumble in its orbit. This is why the radio antennas were designed to provide spherical transmission coverage, so that Sputnik’s orientation would not affect the quality of communication.
Sputnik I used its 1-watt radio transmitter and antennas to communicate with ground stations on two different frequencies: 20.005 and 40.002 MHz. Pulses were emitted on the first frequency at three tenths of a second intervals; during the pauses between pulses the second frequency was utilized.
Sputnik I Was Powered by Three Silver-Zinc Batteries
Sputnik I was powered by its three silver-zinc batteries. Two of the batteries powered the radio transmitter and the third powered the temperature regulation subsystem. The batteries, which were projected to last only for about two weeks, ended up working for 22 days before dying. Power was activated when Sputnik I separated from the second stage of the R-7 rocket.
The payload of Sputnik I was nothing more than its radio transmitter, batteries, temperature and pressure switches, and a cooling fan. It was designed to be as minimal as possible so that Roscosmos could expedite the launch schedule to outpace its American competitors.
There was no apparent commanding from ground stations. Sputnik I’s thermal and barometric switches automatically changed radio transmission rates and activated the cooling fan based on environmental changes. But these events were automatic and required no ground communication involvement.
Sputnik I’s thermal regulation system successfully maintained optimal temperatures, thought to be one of the main reasons why Sputnik I’s batteries lasted as long as they did. Sputnik I’s hull was also filled with nitrogen, which helped to regulate temperature fluctuations.
Sputnik I’s Elliptical Orbit Took about 96 Minutes to Complete Each Rotation of Earth
Sputnik I’s elliptical orbit took about 96 minutes to complete each rotation. Its orbital inclination was about 65 degrees, which meant that Sputnik I flew over most of the surface of the Earth during its many orbits in three months before it burned up in the atmosphere. However, Sputnik I communicated with Earth only during the first three weeks in orbit. Its onboard batteries died after this point. At the time of its re-entry, Sputnik I had completed 1,440 orbits and traveled 43 million miles.
Sputnik was an overall success. It achieved orbit, which — as the first man-made object to do so — was a feat in itself. But it also successfully transmitted data back to Soviet ground stations that was useful in engineering subsequent versions of satellite spacecraft.
In the next article, we’ll look at Sputnik II, the follow-on mission to Sputnik I.
About the Author
Dr. Gary Deel is a Faculty Director with the School of Business at American Military University. He holds a J.D. in Law and a Ph.D. in Hospitality/Business Management. Gary teaches human resources and employment law classes for American Military University, the University of Central Florida, Colorado State University and others.