Ever since humanity first began to theorize about the nature of space and our planet's place within it we have dreamed of placing objects in the heavens looping the planet, even when we believed it incorrectly to be the center of the Universe. Around 1610, German astronomer Johannes Kepler first used the term "satellite" — a Latin word meaning "one who escorts or follows after an important person" — to describe the moons orbiting Jupiter.
What is a satellite and how do they stay in orbit?
Satellites can sit in different orbits around the Earth depending on what their function is.
Geostationary (GEO) satellites orbit Earth at an altitude of 22,236 miles and rotate at the same rate as the planet locked to its equator. Low-earth orbit (LEO) satellites, on the other hand, orbit at an altitude of between around 100 miles and 620 miles.. These satellites have a bit more freedom in the path they take around the planet, but can spend time over unoccupied areas like deserts or oceans, so communications roles are reserved for satellites in GEO orbits. One of the key aspects of placing a satellite into space is knowing it will stay there in orbit around the planet. As mentioned above, the theories that underlie this were formulated as early as the 1600s in the work of Kepler and Newton. The National Environment Satellite Data and Information Service (NOAA) satellite stays in orbit by achieving a perfect balance between velocity and the gravitational pull that our planet exerts on it. The closer to Earth a satellite orbits, the more rapidly it has to move to stay one step ahead of this gravitational pull. According to the European Space Agency (ESA), LEO satellites orbit at a speed of around 7.8 km per second — taking about 90 minutes to fully circle Earth.
The first artificial satellite
The first artificial satellite, Sputnik 1, was launched from Baikonur Cosmodrome at Tyuratam, Kazakhstan — which was at the time part of the Soviet Union — on October 4, 1957. The Russian satellite — with a name that means "companion" — was the first in a series of four satellites launched as part of the Sputnik program. An aluminum sphere with a diameter of 58 centimeters, Sputnik 1 had four whip-like antennas between 2.4 meters and 2.9 meters long, which almost resembled "whiskers" from one side of the craft. One of the main roles of Sputnik 1 was to collect data regarding the density of the upper layers of the atmosphere and how radio signals travel through the ionosphere — the ionized part of Earth's upper atmosphere. The craft was capable of detecting meteoroids but failed to spot any in the three weeks of operation before its satellite transmitters stopped operations after its onboard chemical batteries failed. After completing around 1,400 orbits of Earth over 92 days, Sputnik 1 dropped out of orbit from an altitude of around 600 miles above the planet, breaking apart during its descent.
NASA enters the satellite race
A few months after the successful launch of Sputnik, on the last day of January 1958, the United States would place its own satellite in orbit. NASA's Jet Propulsion Laboratory (JPL) at the California Institute of Technology (Caltech) built the craft — designated Explorer 1 — which led to James Van Allen's discovery of radiation belts around Earth held in place by the planet's magnetic field. On its website, JPL describes the launch of this satellite, Explorer 1. It writes: "A quick response to the Soviet Union's launch of Sputnik 1, Explorer 1's success marked the beginning of the U.S. Space Age." Its cosmic ray detector, provided by Van Allen made Explorer 1 the first satellite to carry science instruments into orbit. Explorer 1 revolved around Earth in a looping orbit between 220 miles to 1,563 miles above Earth. The 203 cm long and 16 cm wide craft made an orbit every 114.8 minutes and a total of just over 12 and a half orbits per day. NASA says Explorer 1 made its final transmission on May 23, 1958. Almost 12 years later on March 31, 1970, the craft entered Earth's atmosphere following over 58,000 orbits of the planet.
One of the most common and important jobs for satellites is the monitoring of Earth's weather. While the first weather imaging satellite entered the planning stages in 1946, it would take 14 years to implement. On April 1, 1960, NASA launched TIROS-1 (Television Infrared Observation Satellite). TIROS was the first weather satellite to be designed by NASA but was beaten to orbit by Vanguard 2 — which launched on February 17, 1959, as part of the U.S Navy's Project Vanguard. Not only did Vanguard 2 mean that the U.S. had a weather satellite before Russia, but the craft also remains in orbit to this day and is expected to remain around Earth for as long as 300 years. Vanguard 2's primary mission was to observe cloud cover on Earth from space. The mission of TIROS was to test the feasibility of weather satellites and to try out experimental television techniques designed to develop a worldwide meteorological satellite information system. TIROS-I would not have the longevity of Vanguard 2, reaming operational for only 78 days. Yet in this period the craft was able to prove that satellites could be useful tools for surveying global weather conditions from space.
Information and entertainment in the space age
The landscape of our entertainment industry would be completely different today if not for satellites, as would the way we communicate information across the globe. As mentioned above, speculation about the use of satellites to transmit information began at least a decade before the first artificial satellite had made it to orbit. It would take until 1962 for the space age of communication to begin. On July 10 of that year, Telstar 1 developed by the American Telephone and Telegraph Company (AT&T), was the world's first active communications satellite to be launched. Shortly after the launch the white spherical spacecraft with an exterior covered with solar cells, linked the U.S. and France thus facilitating the first transatlantic television transmission. Unfortunately, Telstar wouldn't remain in operation for long. In November of the same year, as it launched, radiation from the Van Allen belt fried its electronics. This led to its deactivation in February of 1963.
Satellites go global: Other countries enter the space race
The U.S. and Russia weren't the only countries to get involved in the new space age. France and Japan would be the first two countries to launch satellites outside of the superpowers in 1965 and 1970, respectively. Also in 1970, China would become the fifth country to launch a satellite when it blasted Dongfanghong 1 into Earth orbit on its Long March rocket. The United Kingdom launched its first satellite, the Prospero, in 1971 from Woomera, Australia, atop a Black Arrow rocket.
International collaboration became a key part of satellite launches in 1979 when the European Space Agency (ESA) launched Ariane-1 carrying two telecommunications satellites. Without this international collaboration, it would have been impossible to launch what is arguably humanity's most ambitious satellite — the International Space Station (ISS). The ISS — a collaboration involving Russia, the USA, the European Union, Japan, and Canada — would launch in 1998. It remains in operation to this day.
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