Reaction wheel in the context of "Rocket"

⭐ In the context of rockets, reaction wheels are considered a method of controlling flight by…

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⭐ Core Definition: Reaction wheel

A reaction wheel (RW) is an electric motor attached to a flywheel, which, when its rotation speed is changed, causes a counter-rotation proportionately through conservation of angular momentum. A reaction wheel can rotate only around its center of mass; it is not capable of moving from one place to another (translational force).

Reaction wheels are used primarily by spacecraft for three-axis fine attitude control, but can also be used for fast detumbling. Reaction wheels do not require rockets or external applicators of torque, which reduces the mass fraction needed for fuel. They provide a high pointing accuracy, and are particularly useful when the spacecraft must be rotated by very small amounts, such as keeping a telescope pointed at a star.

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👉 Reaction wheel in the context of Rocket

A rocket (from Italian: rocchetto, lit. ''bobbin/spool'', and so named for its shape) is an elongated flying vehicle that uses a rocket engine to accelerate without using any surrounding air. A rocket engine produces thrust by reaction to exhaust expelled at high speed. Unlike jet engines, rockets are fuelled entirely by propellant which they carry, without the need for oxygen from air; consequently a rocket can fly in the vacuum of space. Rockets suffer deceleration by atmospheric drag in air, and operate more efficiently outside the atmosphere.

Multistage rockets are capable of attaining escape velocity from Earth and therefore can achieve unlimited maximum altitude. Compared with airbreathing engines, rockets are lightweight and powerful and capable of generating large accelerations. To control their flight, rockets may use momentum, airfoils, auxiliary reaction engines, gimballed thrust, momentum wheels, deflection of the exhaust stream, propellant flow, and spin, or may simply fly in a ballistic trajectory under the influence of gravity.

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Reaction wheel in the context of Solar and Heliospheric Observatory

The Solar and Heliospheric Observatory (SOHO) is a European Space Agency (ESA) spacecraft built by a European industrial consortium led by Matra Marconi Space (now Airbus Defence and Space) that was launched on a Lockheed Martin Atlas IIAS launch vehicle on 2 December 1995, to study the Sun. It has also discovered more than 5,000 comets. It began normal operations in May 1996. It is a joint project between the European Space Agency (ESA) and NASA. SOHO was part of the International Solar Terrestrial Physics Program (ISTP). Originally planned as a two-year mission, SOHO continues to operate after 29 years in space; the mission has been extended until the end of 2025, subject to review and confirmation by ESA's Science Programme Committee.

In addition to its scientific mission, it is a main source of near-real-time solar data for space weather prediction. Along with Aditya-L1, Wind, Advanced Composition Explorer (ACE), Deep Space Climate Observatory (DSCOVR) and other satellites, SOHO is one of five spacecraft in the vicinity of the Earth–Sun L1 point, a point of gravitational balance located approximately 0.99 astronomical unit (AU) from the Sun and 0.01 AU from the Earth. In addition to its scientific contributions, SOHO is distinguished by being the first three-axis-stabilized spacecraft to use its reaction wheels as a kind of virtual gyroscope; the technique was adopted after an on-board emergency in 1998 that nearly resulted in the loss of the spacecraft.

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Reaction wheel in the context of Spacecraft propulsion

Spacecraft propulsion is any method used to accelerate spacecraft and artificial satellites. In-space propulsion exclusively deals with propulsion systems used in the vacuum of space and should not be confused with space launch or atmospheric entry.

Several methods of pragmatic spacecraft propulsion have been developed, each having its own drawbacks and advantages. Most satellites have simple reliable chemical thrusters (often monopropellant rockets) or resistojet rockets for orbital station-keeping, while a few use momentum wheels for attitude control. Russian and antecedent Soviet bloc satellites have used electric propulsion for decades, and newer Western geo-orbiting spacecraft are starting to use them for north–south station-keeping and orbit raising. Interplanetary vehicles mostly use chemical rockets as well, although a few have used electric propulsion such as ion thrusters and Hall-effect thrusters. Various technologies need to support everything from small satellites and robotic deep space exploration to space stations and human missions to Mars.

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LINKED FROM (PARENTS)
← Rocket ← Solar and Heliospheric Observatory ← Spacecraft propulsion ← Rockets
LINKS TO (CHILDREN)
Flywheel → Angular momentum → Center of mass → Translation (physics) → Spacecraft → Spacecraft attitude control → Spacecraft detumbling → Rocket engine → Torque → Payload fraction →