Introduction to CelestLab
CelestLab is a library of space mechanics functions for Scilab.
It has been developed by CNES-DCT/SB (Centre National d’Etudes Spatiales -
French Space Agency) for mission analysis purposes.
CelestLab can be used for trajectory analysis and orbit
design for various types of space missions. It allows engineers to perform tasks
such as: orbit propagation, attitude computation, elementary manoeuvre computation,
change of reference frame, change of coordinate systems, ...
The functions are arranged into several categories:
- Coordinates and frames:
Definition of reference frames, time scales, types of coordinate systems,...
- Geometry and events:
Computation of orbital geometry and orbital events (ground station visibility, ...)
- Interplanetary:
Interplanetary and 3-body problem
- Math:
Mathematical functions
- Models:
Models for atmospheric density, Sun and Moon position,...
- Orbit Properties:
Orbit properties (Sun synchronicity, repeating ground tracks, frozen orbits,
drift of orbital elements, ...)
- Relative motion:
Relative trajectory analysis using Clohessy Whiltshire formalism
- Trajectory and maneuvers:
Orbit propagation and maneuver computation
- Utilities:
Miscellaneous and multi-purpose functions
Installing and loading CelestLab
CelestLab can be installed in two different (and equivalent) ways:
- by using ATOMS:
Simply execute the command:
atomsInstall("celestlab");
- manually:
1) Unzip/copy the celestLab directory to a location of your choice.
Let's call CelestLabRoot the new CelestLab path.
If the distribution only contains source files, create the library by executing the command:
exec(fullfile(CelestLabRoot, "builder.sce"));
2) Load CelestLab by executing the command:
exec(fullfile(CelestLabRoot, "loader.sce"));
(For convenience, you can add this latter line in the scilab.ini file.)
Loading CelestLab makes one (global) variable appear: %CL__PRIV. It is intended
for CelestLab internal use only (and consequently, should not be used).
Using CelestLab
All CelestLab functions are directly useable after CelestLab has been loaded;
no special action is required. You can browse the help files (in particular the "Introduction" section),
and run some of the examples. You can also type “help function” (e.g. “help CL_dat_convert”)
if you know what you're looking for (this is not specific to CelestLab).
Another good way to start is to try the demos. Select "demos" in the CelestLab menu, then select one "topic"
and one "application". Each demo corresponds to one single script that can be used as an example (although some of them
are not that simple).
It is also possible to bring some useful (local) variables into existence (commonly used quantities or conversion
factors, values of optional arguments) by just typing CL_init().
Note:
CL_init is only a convenience function. CelestLab is fully functional even
if CL_init has not been called.
A call to CL_init can be added to the scilab.ini file in order to
make the variables exist each time celestLab is loaded.