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NASA Earth science satellite fleet as of September 2020, planned through 2023. Earth observation satellite missions developed by the ESA as of 2019. Earth observation satellites are Earth-orbiting spacecraft with sensors used to collect imagery and measurements of the surface of the earth. These satellites are used to monitor short-term weather ...
This timeline of artificial satellites and space probes includes uncrewed spacecraft including technology demonstrators, observatories, lunar probes, and interplanetary probes. First satellites from each country are included. Not included are most Earth science satellites, commercial satellites or crewed missions .
Every satellite, space probe, and crewed mission has the potential to produce space debris. The theoretical cascading Kessler syndrome becomes more likely as satellites in orbit increase in number. As of 2014, there were about 2,000 commercial and government satellites orbiting the Earth, [23] and as of 2021 more than 4000. [24]
A low Earth orbit ( LEO) is an orbit around Earth with a period of 128 minutes or less (making at least 11.25 orbits per day) and an eccentricity less than 0.25. [1] Most of the artificial objects in outer space are in LEO, peaking in number at an altitude around 800 km (500 mi), [2] while the farthest in LEO, before medium Earth orbit (MEO ...
It can be said that two objects in space orbiting each other in the absence of other forces are in free fall around each other, e.g. that the Moon or an artificial satellite "falls around" the Earth, or a planet "falls around" the Sun. Assuming spherical objects means that the equation of motion is governed by Newton's law of universal ...
Astrodynamics. Orbital mechanics or astrodynamics is the application of ballistics and celestial mechanics to the practical problems concerning the motion of rockets, satellites, and other spacecraft. The motion of these objects is usually calculated from Newton's laws of motion and the law of universal gravitation.
Geosynchronous orbit. A geosynchronous orbit (sometimes abbreviated GSO) is an Earth-centered orbit with an orbital period that matches Earth's rotation on its axis, 23 hours, 56 minutes, and 4 seconds (one sidereal day ). The synchronization of rotation and orbital period means that, for an observer on Earth's surface, an object in ...
Weightlessness is the complete or near-complete absence of the sensation of weight, i.e., zero apparent weight. It is also termed zero g-force, or zero-g (named after the g-force) [ 1] or, incorrectly, zero gravity . Microgravity environment is more or less synonymous in its effects, with the recognition that g-forces are never exactly zero.