Diseases, Conditions, Syndromes

New coronavirus may have emerged in summer 2019, study suggests

A surge in hospital visits and internet searches related to COVID-19 symptoms from the Chinese city of Wuhan suggests the coronavirus may have been circulating since August 2019, according to a preliminary study by researchers ...

Diseases, Conditions, Syndromes

Social scientists worldwide collaborate on COVID-19

More than 100 international social scientists are working together to collect immediate and longitudinal information on the key social science factors that might predict the spread of COVID-19. The project, known as PsyCorona, ...

Diseases, Conditions, Syndromes

Aerial images reveal virus emptying famed sites

Empty public squares, a ghostly train station and deserted holy sites—a series of striking satellite images have revealed the impact of the coronavirus epidemic on some of the world's busiest spaces.

Medical research

Strong change of course for muscle research

Anyone who climbs the 285 steps to the viewing platform of Berlin's Siegessäule, or Victory Column, will probably have quite a few sore muscles the next day. Out-of-the-ordinary activities such as climbing lots of steps ...

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Satellite

In the context of spaceflight, a satellite is an object which has been placed into orbit by human endeavor. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon.

The first artificial satellite, Sputnik 1, was launched by the Soviet Union in 1957. By 2009 thousands of satellites have been launched into orbit around the Earth. These originate from more than 50 countries and have used the satellite launching capabilities of ten nations. A few hundred satellites are currently operational, whereas thousands of unused satellites and satellite fragments orbit the Earth as space debris. A few space probes have been placed into orbit around other bodies and become artificial satellites to the Moon, Venus, Mars, Jupiter and Saturn.

Satellites are used for a large number of purposes. Common types include military (spy) and civilian Earth observation satellites, communication satellites, navigation satellites, weather satellites, and research satellites. Space stations and human spacecraft in orbit are also satellites. Satellite orbits vary greatly, depending on the purpose of the satellite, and are classified in a number of ways. Well-known (overlapping) classes include low Earth orbit, polar orbit, and geostationary orbit.

Satellites are usually semi-independent computer controlled systems. Satellite subsystems attend many tasks, such as power generation, thermal control, telemetry, attitude control and orbit control.

This text uses material from Wikipedia, licensed under CC BY-SA