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An inertial measurement unit (IMU) is an electronic device that measures and reports a body's specific force, angular rate, and sometimes the orientation of the body, using a combination of accelerometers, gyroscopes, and sometimes magnetometers. When the magnetometer is included, IMUs are referred to as IMMUs. [1]
Apollo's GN&C. Guidance, navigation and control (abbreviated GNC, GN&C, or G&C) is a branch of engineering dealing with the design of systems to control the movement of vehicles, especially, automobiles, ships, aircraft, and spacecraft. In many cases these functions can be performed by trained humans.
A well-known gimbal lock incident happened in the Apollo 11 Moon mission. On this spacecraft, a set of gimbals was used on an inertial measurement unit (IMU). The engineers were aware of the gimbal lock problem but had declined to use a fourth gimbal. [5] Some of the reasoning behind this decision is apparent from the following quote:
Analogous to linear motion, the angular rotation rate (degrees per second) is obtained by integrating α over time: = and the angular rotation is the time integral of the rate: = The three principal moments of inertia I x , I y , and I z about the roll, pitch and yaw axes, are determined through the vehicle's center of mass .
The Apollo program used parking orbits, for all the reasons mentioned above except those that pertain to geostationary orbits. [7] [8] When the Space Shuttle orbiter launched interplanetary probes such as Galileo, it used a parking orbit to deliver the probe to the right injection spot. [9] The Ariane 5 does not usually use parking orbits. [10]
A small reaction wheel viewed in profile A momentum/reaction wheel comprising part of a high-accuracy Conical Earth Sensor to maintain a satellite's precise attitude. 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. [1]
A diagram of a typical nautical sextant, a tool used in celestial navigation to measure the angle between two objects viewed by means of its optical sight. Celestial navigation, also known as astronavigation, is the practice of position fixing using stars and other celestial bodies that enables a navigator to accurately determine their actual current physical position in space or on the ...
Delta-v in feet per second, and fuel requirements for a typical Apollo Lunar Landing mission. In astrodynamics and aerospace , a delta-v budget is an estimate of the total change in velocity ( delta- v ) required for a space mission .