Spec_LocalCelestialInformation.md

Specification for Local Celestial Information

1. Overview

1. Functions

• LocalCelestialInformation calculates the celestial bodies position and velocity on the spacecraft body-fixed frame.

2. Related files

• src/environment/local/local_celestial_information.cpp, .hpp
  • LocalCelestialInformation class is defined.
• src/environment/local/local_environment.cpp, .hpp
  • LocalCelestialInformation class is used here as a member variable of LocalEnvironment class.

3. How to use

• Call UpdateAllObjectsInformation function to calculates the celestial bodies position and velocity.
• Users can get calculated values by using the following functions:
  • Get celestial body position vector from the spacecraft position. Users need to set the body name as an argument.
    • GetPositionFromSpacecraft_i_m
    • GetPositionFromSpacecraft_b_m
  • Get center body position vector from the spacecraft position without any arguments.
    • GetCenterBodyPositionFromSpacecraft_i_m
    • GetCenterBodyPositionFromSpacecraft_b_m
• To access the celestial body position in the inertial frame, users can use GetGlobalInformation

3. Explanation of Algorithm

1. UpdateAllObjectsInformation function

1. overview

• Convert the celestial bodies positions to the body frame from the inertial frame.

4. Verification

• NA

5. References

• NA