The first published mathematical study of the possibility of an artificial satellite was Newton's cannonball, a thought experiment by Isaac Newton to explain the motion of natural satellites, in his Philosophiæ Naturalis Principia Mathematica (1687). The first fictional depiction of a satellite being launched into orbit was a short story by Edward Everett Hale, "The Brick Moon" (1869).[3][4] The idea surfaced again in Jules Verne's The Begum's Fortune (1879).
In 1903, Konstantin Tsiolkovsky (1857–1935) published Exploring Space Using Jet Propulsion Devices, which is the first academic treatise on the use of rocketry to launch spacecraft. He calculated the orbital speed required for a minimal orbit, and that a multi-stage rocket fueled by liquid propellants could achieve this.
In 1928, Herman Potočnik (1892–1929) published his sole book, The Problem of Space Travel – The Rocket Motor. He described the use of orbiting spacecraft for observation of the ground and described how the special conditions of space could be useful for scientific experiments.
In a 1945 Wireless World article, the English science fiction writer Arthur C. Clarke described in detail the possible use of communications satellites for mass communications.[5] He suggested that three geostationary satellites would provide coverage over the entire planet.
In May 1946, the United States Air Force's Project RAND released the Preliminary Design of an Experimental World-Circling Spaceship, which stated that "A satellite vehicle with appropriate instrumentation can be expected to be one of the most potent scientific tools of the Twentieth Century."[6] The United States had been considering launching orbital satellites since 1945 under the Bureau of Aeronautics of the United States Navy. Project RAND eventually released the report, but considered the satellite to be a tool for science, politics, and propaganda, rather than a potential military weapon.[7]
In 1946, American theoretical astrophysicist Lyman Spitzer proposed an orbiting space telescope.[8]
In February 1954 Project RAND released "Scientific Uses for a Satellite Vehicle", written by R.R. Carhart.[9] This expanded on potential scientific uses for satellite vehicles and was followed in June 1955 with "The Scientific Use of an Artificial Satellite", by H.K. Kallmann and W.W. Kellogg.[10]
In the context of activities planned for the International Geophysical Year (1957–58), the White House announced on 29 July 1955 that the U.S. intended to launch satellites by the spring of 1958. This became known as Project Vanguard. On 31 July, the Soviets announced that they intended to launch a satellite by the fall of 1957.
The first artificial satellite was Sputnik 1, launched by the Soviet Union on 4 October 1957 under the Sputnik program, with Sergei Korolev as chief designer. Sputnik 1 helped to identify the density of high atmospheric layers through measurement of its orbital change and provided data on radio-signal distribution in the ionosphere. The unanticipated announcement of Sputnik 1's success precipitated the Sputnik crisis in the United States and ignited the so-called Space Race within the Cold War.
Sputnik 2 was launched on 3 November 1957 and carried the first living passenger into orbit, a dog named Laika.[11]
In early 1955, following pressure by the American Rocket Society, the National Science Foundation, and the International Geophysical Year, the Army and Navy were working on Project Orbiter with two competing programs. The army used the Jupiter C rocket, while the civilian/Navy program used the Vanguard rocket to launch a satellite. Explorer 1 became the United States' first artificial satellite on 31 January 1958.[12]
In June 1961, three-and-a-half years after the launch of Sputnik 1, the United States Space Surveillance Network cataloged 115 Earth-orbiting satellites.[13]
Early satellites were constructed to unique designs. With advancements in technology, multiple satellites began to be built on single model platforms called satellite buses. The first standardized satellite bus design was the HS-333 geosynchronous (GEO) communication satellite launched in 1972.
Currently the largest artificial satellite ever is the International Space Station.[14]
Tracking
Main article: Ground station
Further information: Orbit determination, Satellite geodesy § Satellite tracking, and Satellite flare
See also: Space debris § Tracking and measurement, and Satellite tracking (animal migration)
Satellites can be tracked from Earth stations and also from other satellites.
Space Surveillance Network
Main article: United States Space Surveillance Network
The United States Space Surveillance Network (SSN), a division of the United States Strategic Command, has been tracking objects in Earth's orbit since 1957 when the Soviet Union opened the Space Age with the launch of Sputnik I. Since then, the SSN has tracked more than 26,000 objects. The SSN currently tracks more than 8,000-artificial orbiting objects. The rest have re-entered Earth's atmosphere and disintegrated, or survived re-entry and impacted the Earth. The SSN tracks objects that are 10 centimeters in diameter or larger; those now orbiting Earth range from satellites weighing several tons to pieces of spent rocket bodies weighing only 10 pounds. About seven percent are operational satellites (i.e. ~560 satellites), the rest are space debris.[15] The United States Strategic Command is primarily interested in the active satellites, but also tracks space debris which upon reentry might otherwise be mistaken for incoming missiles.
Services
There are three basic categories of (non-military) satellite services:[16]
Fixed satellite services
Fixed satellite services handle hundreds of billions of voice, data, and video transmission tasks across all countries and continents between certain points on the Earth's surface.
Mobile satellite systems
Main article: Mobile-satellite service
Mobile satellite systems help connect remote regions, vehicles, ships, people and aircraft to other parts of the world and/or other mobile or stationary communications units, in addition to serving as navigation systems.
Scientific research satellites (commercial and noncommercial)
Scientific research satellites provide meteorological information, land survey data (e.g. remote sensing), Amateur (HAM) Radio, and other different scientific research applications such as earth science, marine science, and atmospheric research.
Tyes
Astronomical satellites are satellites used for observation of distant planets, galaxies, and other outer space objects.
The Hubble Space Telescope
Biosatellites are satellites designed to carry living organisms, generally for scientific experimentation.
Communication satellites are satellites stationed in space for the purpose of telecommunications. Modern communications satellites typically use geosynchronous orbits, Molniya orbits or Low Earth orbits.
Earth observation satellites are satellites intended for non-military uses such as environmental monitoring, meteorology, map making etc. (See especially Earth Observing System.)
Navigational satellites are satellites that use radio time signals transmitted to enable mobile receivers on the ground to determine their exact location. The relatively clear line of sight between the satellites and receivers on the ground, combined with ever-improving electronics, allows satellite navigation systems to measure location to accuracies on the order of a few meters in real time.
Killer satellites are satellites that are designed to destroy enemy warheads, satellites, and other space assets.
Crewed spacecraft (spaceships) are large satellites able to put humans into (and beyond) an orbit, and return them to Earth. (The Lunar Module of the U.S. Apollo program was an exception, in that it did not have the capability of returning human occupants to Earth.) Spacecraft including spaceplanes of reusable systems have major propulsion or landing facilities. They can be used as transport to and from the orbital stations.
Miniaturized satellites are satellites of unusually low masses and small sizes.[17] New classifications are used to categorize these satellites: minisatellite (500–1000 kg), microsatellite (below 100 kg), nanosatellite (below 10 kg).[citation needed]
Reconnaissance satellites are Earth observation satellite or communications satellite deployed for military or intelligence applications. Very little is known about the full power of these satellites, as governments who operate them usually keep information pertaining to their reconnaissance satellites classified.
Recovery satellites are satellites that provide a recovery of reconnaissance, biological, space-production and other payloads from orbit to Earth.
Space-based solar power satellites are proposed satellites that would collect energy from sunlight and transmit it for use on Earth or other places.
Space stations are artificial orbital structures that are designed for human beings to live on in outer space. A space station is distinguished from other crewed spacecraft by its lack of major propulsion or landing facilities. Space stations are designed for medium-term living in orbit, for periods of weeks, months, or even years.
International Space Station
Tether satellites are satellites that are connected to another satellite by a thin cable called a tether.
Weather satellites are primarily used to monitor Earth's weather and climate.[18]