- Spin-stabilized satellite
A spin-stabilized satellite is a
satellitewhich has the motion of one axis held (relatively) fixed by spinning the satellite around that axis, using the gyroscopiceffect.
The attitude of a
satelliteor any rigid bodyis its orientation in space. If such a body initially has a fixed orientation (relative inertial space) it will start to wobble because it will always be subject to small torques. The easiest form of attitude stabilization is to give the rigid body an initial spin around a principal axis. This is what is done to for example a riflebullet. Because of the rotation the spin axis will be (essentially) fixed relative inertial spacebecause of the gyroscopiceffect.
This method to stabilize one axis is utilized also for many spacecraft, these spacecraft are said to be spin stabilized. For some types of spacecraft such a rotation is an advantage also for other aspects of the mission. If the spin axis makes a angle to the Sun direction that is approximately 90 deg the heating effects of the Sun will be rather uniformly distributed over the surface (the "
barbecueeffect"). Sometimes the rotation can also be useful for instruments that should scan the environment. But most modern spacecraft have a panel with solar cellsthat should be directed towards the Sun and antennas that should be directed towards the Earth. These spacecraft are then instead kept in a desired attitude with an active attitude control using attitude sensors to detect mispointing and attitude control actuators, mostly momentum wheels or thrusters, to compensate for the outer torques and to keep the spacecraft in the desired attitude. This type of attitude control is called "3-axis stablization".
The entire space vehicle itself can be spun up to stabilize the orientation of a single vehicle axis. This method is widely used to stabilize the final stage of a launch vehicle. The entire spacecraft and an attached solid rocket motor are spun up about the rocket's thrust axis, on a "spin table" oriented by the attitude control system of the lower stage on which the spin table is mounted. When final orbit is achieved, the satellite may be de-spun by various means, or left spinning. Spin stabilization of satellites is only applicable to those missions with a primary axis of orientation that need not change dramatically over the lifetime of the satellite and no need for extremely high precision pointing. It is also useful for missions with instruments that must scan the starfield or the Earth's surface or atmosphere.
Attitude dynamics and control
3 axis stabilized spacecraft
Wikimedia Foundation. 2010.
Look at other dictionaries:
3-axis stabilized spacecraft — 3 axis stabilisation is a design feature of most modern spacecraft whereby the spacecraft utilizes sensor readings to determine how actuators on the spacecraft can be used to keep it in a desired attitude, or orientation in space. Description A… … Wikipedia
Yo-yo de-spin — A yo yo de spin mechanism is a device used to reduce the spin of satellite, typically right after launch. It is basically two lengths of cable with weights on the ends. The cables are wrapped around the final stage and/or satellite, in the manner … Wikipedia
Communications Technology Satellite — The Communications Technology Satellite, also known as Hermes was an experimental high power direct broadcast communications satellite. It was a joint effort of Canada s Department of Communications, who designed and managed it, NASA who launched … Wikipedia
Hermes Communications Technology Satellite — The Hermes Communications Technology Satellite was an experimental high power direct broadcast communications satellite which was also known as the CTS or simply as the Hermes. It was a joint effort of Canada s Department of Communications, who… … Wikipedia
Thor (satellite) — Marcopolo redirects here. For the explorer, see Marco Polo. For any other, please see Marco Polo (disambiguation) Thor (previously known as Marcopolo) is a family of satellites designed, launched and tested by Hughes Space and Communications (now … Wikipedia
Defense Satellite Communications System — The Defense Satellite Communications System (DSCS) provides the United States with military communications to support globally distributed military users. DSCS will be replaced by the Wideband Global SATCOM system. A total of 14 DSCS III… … Wikipedia
Active Cavity Radiometer Irradiance Monitor Satellite — ACRIMSAT is the acronym for Active Cavity Radiometer Irradiance Monitor Satellite. It is a dedicated satellite and instrument that is one of the 21 primary observational components of NASA s Earth Observing System program. Acrimsat was launched… … Wikipedia
AEROS (satellite) — AEROScite book|author=Yenne, Bill|title= The Encyclopedia of US Spacecraft |publisher=Exeter Books (A Bison Book), New York|year=1985|id=ISBN 0 671 07580 2p.12 AEROS] satellite was to study the science of the upper atmosphere and ionospheric F… … Wikipedia
Injun (satellite) — The Injun program was a series of six satellites designed and built by researchers at the University of Iowa. They were intended to observe various radiation and magnetic phenomena in the ionosphere and beyond.The design specifics of the… … Wikipedia
Television Infrared Observation Satellite — TIROS, or Television Infrared Observation Satellite, was a series of early weather satellites launched by NASA, beginning with TIROS 1 in 1960. The program was extremely successful in proving the usefulness of satellite weather observation and in … Wikipedia