Types Of Satellites And Their Uses Pdf
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In-depth details on the 3, satellites currently orbiting Earth, including their country of origin, purpose, and other operational details. Published Dec 8, Updated Jan 1, Assembled by experts at the Union of Concerned Scientists UCS , the Satellite Database is a listing of the more than 3, operational satellites currently in orbit around Earth. Our intent in producing the database is to create a research tool for specialists and non-specialists alike by collecting open-source information on operational satellites and presenting it in a format that can be easily manipulated for research and analysis. It is available as both a downloadable Excel file and in a tab-delimited text format.
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World Space Week will celebrate the impact of satellites on humanity from Oct. Find out how to celebrate here and check out the history of satellites below! A satellite is an object in space that orbits or circles around a bigger object. There are two kinds of satellites: natural such as the moon orbiting the Earth or artificial such as the International Space Station orbiting the Earth. There are dozens upon dozens of natural satellites in the solar system, with almost every planet having at least one moon.
Saturn, for example, has at least 53 natural satellites , and between and , it also had an artificial one — the Cassini spacecraft , which explored the ringed planet and its moons. Artificial satellites, however, did not become a reality until the midth century. The first artificial satellite was Sputnik , a Russian beach-ball-size space probe that lifted off on Oct. That act shocked much of the western world, as it was believed the Soviets did not have the capability to send satellites into space.
Following that feat, on Nov. The United States' first satellite was Explorer 1 on Jan. The satellite was only 2 percent the mass of Sputnik 2, however, at 30 pounds 13 kg. The Sputniks and Explorer 1 became the opening shots in a space race between the United States and the Soviet Union that lasted until at least the late s. The focus on satellites as political tools began to give way to people as both countries sent humans into space in Later in the decade, however, the aims of both countries began to split.
While the United States went on to land people on the moon and create the space shuttle, the Soviet Union constructed the world's first space station, Salyut 1 , which launched in Other countries began to send their own satellites into space as the benefits rippled through society. Weather satellites improved forecasts, even for remote areas. Land-watching satellites such as the Landsat series tracked changes in forests, water and other parts of Earth's surface over time.
Telecommunications satellites made long-distance telephone calls and eventually, live television broadcasts from across the world a normal part of life. Later generations helped with Internet connections. With the miniaturization of computers and other hardware, it's now possible to send up much smaller satellites that can do science, telecommunications or other functions in orbit.
It's common now for companies and universities to create "CubeSats", or cube-shaped satellites that frequently populate low-Earth orbit. These can be lofted on a rocket along with a bigger payload, or sent from a mobile launcher on the International Space Station ISS. The ISS is the biggest satellite in orbit, and took over a decade to construct. Piece by piece, 15 nations contributed financial and physical infrastructure to the orbiting complex, which was put together between and Program officials expect the ISS to keep running until at least Every usable artificial satellite — whether it's a human or robotic one — has four main parts to it : a power system which could be solar or nuclear, for example , a way to control its attitude, an antenna to transmit and receive information, and a payload to collect information such as a camera or particle detector.
As will be seen below, however, not all artificial satellites are necessarily workable ones. Even a screw or a bit of paint is considered an "artificial" satellite, even though these are missing these parts. A satellite is best understood as a projectile, or an object that has only one force acting on it — gravity. Technically speaking, anything that crosses the Karman Line at an altitude of kilometers 62 miles is considered in space.
However, a satellite needs to be going fast — at least 8 km 5 miles a second — to stop from falling back down to Earth immediately. If a satellite is traveling fast enough, it will perpetually "fall" toward Earth, but the Earth's curvature means that the satellite will fall around our planet instead of crashing back on the surface. Satellites that travel closer to Earth are at risk of falling because the drag of atmospheric molecules will slow the satellites down.
Those that orbit farther away from Earth have fewer molecules to contend with. There are several accepted "zones" of orbits around the Earth. One is called low-Earth-orbit , which extends from about to 2, km about to 1, miles. This is the zone where the ISS orbits and where the space shuttle used to do its work.
In fact, all human missions except for the Apollo flights to the moon took place in this zone. Most satellites also work in this zone.
Geostationary or geosynchronous orbit is the best spot for communications satellites to use, however. This is a zone above Earth's equator at an altitude of 35, km 22, mi. At this altitude, the rate of "fall" around the Earth is about the same as Earth's rotation, which allows the satellite to stay above the same spot on Earth almost constantly.
The satellite thus keeps a perpetual connection with a fixed antenna on the ground, allowing for reliable communications. When geostationary satellites reach the end of their life, protocol dictates they're moved out of the way for a new satellite to take their place. That's because there is only so much room, or so many "slots" in that orbit, to allow the satellites to operate without interference. While some satellites are best used around the equator, others are better suited to more polar orbits — those that circle the Earth from pole to pole so that their coverage zones include the north and south poles.
Examples of polar-orbiting satellites include weather satellites and reconnaissance satellites. There are an estimated half-million artificial objects in Earth orbit today , ranging in size from paint flecks up to full-fledged satellites — each traveling at speeds of thousands of miles an hour. Only a fraction of these satellites are useable, meaning that there is a lot of "space junk" floating around out there.
With everything that is lobbed into orbit, the chance of a collision increases. Space agencies have to consider orbital trajectories carefully when launching something into space. Agencies such as the United States Space Surveillance Network keep an eye on orbital debris from the ground, and alert NASA and other entities if an errant piece is in danger of hitting something vital.
This means that from time to time, the ISS needs to perform evasive maneuvers to get out of the way. Collisions still occur, however. One of the biggest culprits of space debris was the leftovers of a anti-satellite test performed by the Chinese, which generated debris that destroyed a Russian satellite in Also that year, the Iridium 33 and Cosmos satellites smashed into each other, generating a cloud of debris.
NASA, the European Space Agency and many other entities are considering measures to reduce the amount of orbital debris. Some suggest bringing down dead satellites in some way , perhaps using a net or air bursts to disturb the debris from its orbit and bring it closer to Earth.
Others are thinking about refueling dead satellites for reuse, a technology that has been demonstrated robotically on the ISS. Most planets in our solar system have natural satellites, which we also call moons. For the inner planets: Mercury and Venus each have no moons. Earth has one relatively large moon, while Mars has two asteroid-sized small moons called Phobos and Deimos.
Phobos is slowly spiralling into Mars and will likely break apart or fall into the surface in a few thousand years. Beyond the asteroid belt, are four gas giant planets that each have a pantheon of moons. As of late , Jupiter has 69 known moons, Saturn has 53, Uranus has 27 and Neptune has 13 or New moons are occasionally discovered — mainly by missions either past or present, as we can analyze old pictures or by performing fresh observations by telescope.
Saturn is a special example because it is surrounded by thousands of small objects that form a ring visible even in small telescopes from Earth. Scientists watching the rings close-up over 13 years, during the Cassini mission , saw conditions in which new moons might be born.
Scientists were particularly interested in propellers, which are wakes in the rings created by fragments in the rings. Just after Cassini's mission ended in , NASA said it's possible the propellers share elements of planet formation that takes place around young stars' gassy discs.
Even smaller objects have moons, however. Pluto is technically a dwarf planet. However, the people behind the New Horizons mission , which flew by Pluto in , argue its diverse geography makes it more planet-like.
One thing that isn't argued, however, is the number of moons around Pluto. Pluto has five known moons, most of which were discovered when New Horizons was in development or en route to the dwarf planet. A lot of asteroids have moons, too. These small worlds sometimes fly close to the Earth, and the moons pop out in observations with radar. There are also examples of asteroids with rings , such as Chariklo and Chiron.
Many planets and worlds in our solar system have human-made "moons" as well, particularly around Mars — where several probes orbit the planet doing observations of its surface and environment.
The planets Mercury, Venus, Mars, Jupiter and Saturn all had artificial satellites observing them at some point in history. Technically speaking, during the Apollo missions, humans flew in artificial "moons" spacecraft around our own moon between and NASA may even build a " Deep Space Gateway " space station near the moon in the coming decades, as a launching point for human Mars missions.
Fans of the movie "Avatar" will remember that the humans visited Pandora, the habitable moon of a gas giant named Polyphemus. We don't know yet if there are moons for exoplanets, but we suspect — given that the solar system planets have so many moons — that exoplanets have moons as well. In , scientists made an observation of an object that could be interpreted as an exomoon circling an exoplanet , but the observation can't be repeated as it took place as the object moved in front of a star.
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ISRO Indian Satellites List – Study Notes for SSC & Bank Exams in PDF
From weather forecasts to precise positioning, here are the 50 most iconic satellites put up in space. With countless applications, it even found the island Landsat in Canada. Image Credit: ESA. Before losing contact in , EnviSAT did it all. For instance, it studied the oceans, terrain and atmosphere. Because of its massive frame 8 tons , it is a candidate to be removed from orbit. The Corona satellite was a strategic, James Bond-style military satellite in the s that spied on the Soviet Union.
In the context of spaceflight , a satellite is an object that has been intentionally placed into orbit. These objects are called artificial satellites to distinguish them from natural satellites such as Earth's Moon. On 4 October the Soviet Union launched the world's first artificial satellite, Sputnik 1. Since then, about 8, satellites from more than 40 countries have been launched. According to a estimate, some 5, remain in orbit.
Handbook of Satellite Applications pp Cite as. This handbook also provides a multidisciplinary approach that includes technical, operational, economic, regulatory, and market perspectives. These are key areas whereby applications satellite share a great deal.
A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a transponder ; it creates a communication channel between a source transmitter and a receiver at different locations on Earth. Communications satellites are used for television , telephone , radio , internet , and military applications. The high frequency radio waves used for telecommunications links travel by line of sight and so are obstructed by the curve of the Earth. The purpose of communications satellites is to relay the signal around the curve of the Earth allowing communication between widely separated geographical points.
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