Satellite
They have a variety of uses, including communication relay, weather forecasting, navigation (GPS), broadcasting, scientific research, and Earth observation.
Most communication satellites are radio relay stations in orbit and carry dozens of transponders, each with a bandwidth of tens of megahertz.
The first fictional depiction of a satellite being launched into orbit was a short story by Edward Everett Hale, "The Brick Moon" (1869).
In 1903, Konstantin Tsiolkovsky (1857–1935) published Exploring Space Using Jet Propulsion Devices, which was the first academic treatise on the use of rocketry to launch spacecraft.
Herman Potočnik explored the idea of using orbiting spacecraft for detailed peaceful and military observation of the ground in his 1928 book, The Problem of Space Travel.
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.
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.
In the context of activities planned for the International Geophysical Year (1957–1958), the White House announced on 29 July 1955 that the U.S. intended to launch satellites by the spring of 1958.
In early 1955, after being pressured by the American Rocket Society, the National Science Foundation, and the International Geophysical Year, the Army and Navy worked on Project Orbiter with two competing programs.
[14] 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.
Scout rocket from Wallops Island (Virginia, United States) with an Italian launch team trained by NASA.
On 26 November 1965, the Astérix or A-1 (initially conceptualized as FR.2 or FR-2), was put into orbit by a Diamant A rocket launched from the CIEES site at Hammaguir, Algeria.
[21] In different periods, many countries, such as Algeria, Argentina, Australia, Austria, Brazil, Canada, Chile, China, Denmark, Egypt, Finland, France, Germany, India, Iran, Israel, Italy, Japan, Kazakhstan, South Korea, Malaysia, Mexico, the Netherlands, Norway, Pakistan, Poland, Russia, Saudi Arabia, South Africa, Spain, Switzerland, Thailand, Turkey, Ukraine, the United Kingdom and the United States, had some satellites in orbit.
[22] Japan's space agency (JAXA) and NASA plan to send a wooden satellite prototype called LingoSat into orbit in the summer of 2024.
[23] Most satellites use chemical or ion propulsion to adjust or maintain their orbit,[5]: 78 coupled with reaction wheels to control their three axis of rotation or attitude.
[25] Weather satellites monitor clouds, city lights, fires, effects of pollution, auroras, sand and dust storms, snow cover, ice mapping, boundaries of ocean currents, energy flows, etc.
Environmental monitoring satellites can detect changes in the Earth's vegetation, atmospheric trace gas content, sea state, ocean color, and ice fields.
Their uses include early missile warning, nuclear explosion detection, electronic reconnaissance, and optical or radar imaging surveillance.
[citation needed] Since the mid-2000s, satellites have been hacked by militant organizations to broadcast propaganda and to pilfer classified information from military communication networks.
[38] Satellite manufacturing also requires rare elements such as lithium, gold, and gallium, some of which have significant environmental consequences linked to their mining and processing and/or are in limited supply.
[39][40][41] Launch vehicles require larger amounts of raw materials to manufacture and the booster stages are usually dropped into the ocean after fuel exhaustion.
[39] Two empty boosters used for Ariane 5, which were composed mainly of steel, weighed around 38 tons each,[42] to give an idea of the quantity of materials that are often left in the ocean.
[44] The amount of green house gases emitted by rockets is considered trivial as it contributes significantly less, around 0.01%,[45] than the aviation industry yearly which itself accounts for 2-3% of the total global greenhouse gas emissions.
Radicals such as NOx, HOx, and ClOx deplete stratospheric O3 through intermolecular reactions and can have huge impacts in trace amounts.
[43] However, it is currently understood that launch rates would need to increase by ten times to match the impact of regulated ozone-depleting substances.
[46][47] Whilst emissions of water vapour are largely deemed as inert, H2O is the source gas for HOx and can also contribute to ozone loss through the formation of ice particles.
When in a controlled manner satellites reach the end of life they are intentionally deorbited or moved to a graveyard orbit further away from Earth in order to reduce space debris.
[63][64][65][66][67] A report from the SATCON1 workshop in 2020 concluded that the effects of large satellite constellations can severely affect some astronomical research efforts and lists six ways to mitigate harm to astronomy.
Satellite operators now have sophisticated monitoring tools and methods that enable them to pinpoint the source of any carrier and manage the transponder space effectively.
[citation needed] Issues like space debris, radio and light pollution are increasing in magnitude and at the same time lack progress in national or international regulation.
