The goal is to produce a comprehensive library, written in modern Fortran (Fortran 2003/2008), of all the standard orbital mechanics algorithms. This is a work in progress, and is currently in a preliminary state. Currently-implemented and proposed capabilities include:
- Lambert solvers
- Gooding
- Izzo
- Kepler propagators
- Gooding
- Goodyear
- Shepperd
- ODE solvers (with event-finding)
- Runge-Kutta
- Nystrom
- Adams
- Force models
- point mass gravity field
- geopotential gravity
- solar radiation pressure
- atmospheric drag
- relativistic effects
- Reference frames
- IAU_EARTH
- IAU_MOON
- Celestial Body Ephemerides
- JPLEPH
- Alternate equations of motion
- Circular restricted three-body problem
- Clohessy-Wiltshire
- Modified equinoctial elements
- Misc
- orbital element conversions
- targeting and optimization
- spacecraft engine models
The plots generated by the examples are done using the pyplot-fortran module. In order for the build script to see this module, you have to manually put the pyplot_module.f90
file in the tests
directory.
To use the ephemeris_module, a copy of one of the JPL binary ephemeris files must be present in the eph
directory. This can be built from the instructions at: ftp://ssd.jpl.nasa.gov/pub/eph/planets/fortran/userguide.txt. For example (on Linux):
wget ftp://ssd.jpl.nasa.gov/pub/eph/planets/fortran/*
wget ftp://ssd.jpl.nasa.gov/pub/eph/planets/ascii/de405/*
#edit asc2eph.f file to set NRECL = 4:
sed -i '_original' '/^C.*PARAMETER ( NRECL = 4 )/s/^C//' asc2eph.f
gfortran asc2eph.f -o asc2eph
cat header.405 ascp*.405 | ./asc2eph
mkdir Fortran-Astrodynamics-Toolkit/eph
mv JPLEPH Fortran-Astrodynamics-Toolkit/eph/JPLEPH.405
Note that some of the examples require the file to be named JPLEPH_2000-2100.405
.
To use the geopotential_module, you need a geopotential model file (for example GGM03C.GEO
from ftp://ftp.csr.utexas.edu/pub/grace/GGM03/GGM03_Archive.zip). This should be placed in the grav
directory. For example:
wget ftp://ftp.csr.utexas.edu/pub/grace/GGM03/GGM03_Archive.zip
unzip GGM03_Archive.zip
mkdir Fortran-Astrodynamics-Toolkit/grav
cp GGM03_Archive/GGM03C.GEO Fortran-Astrodynamics-Toolkit/grav