Welcome to JAT

Overview

JAT is a is a library of components to help users create their own application programs to solve problems in Astrodynamics, mission design, spacecraft navigation, guidance and control using Java or Matlab. It is not an application program, although there are a number of example programs included. You have to be able to write Java or Matlab programs to use JAT.

Example programs are available to demonstrate the capabilities of JAT as well as to allow new users to quickly learn how to make use of the built -in features of JAT.

JAT is an open source project hosted by SourceForge.net: JAT SourceForge Project Page

Introduction

After using COTS Astrodynamics software, we have learned that no one application can satisfy all the needs of a researcher in the field of Astrodynamics. Therefore, we decided that JAT should be a software component library so that the users could have flexibility to create their own applications. However, since we are asking users to develop their own applications, the software components must be easy to integrate and use.

The choice of the programming language is usually a design time issue. However, in this project, the Java programming language was chosen for the following reasons:

  1. Java is the preferred programming language of the initiators of the project
  2. The initiators of the project already have a significant amount of source code in Java for the project
  3. Java microchips might enable use of this software for spacecraft control in the future.
  4. Java is faster than Matlab.
  5. Java is portable. There is no need to modify source code to run on different platforms.
  6. Java is object oriented, making it easier to reuse and maintain code.
  7. It is easier to write bug-free code in Java because there is no pointer arithmetic and the Java compiler prevents a lot of errors.
  8. Javadoc provides an easy way to document the code so that it can easily be used by others.
  9. Everything needed to develop Java is available for free!

Features

  • Astrodynamics constants
  • Time transformations
  • Coordinate transformations
  • Quaternions
  • Orbit element conversions
  • Gravity models: Two-body, Restricted three body problem, JGM-3
  • Attitude Dynamics
  • Third body effects due to sun and moon
  • Atmospheric drag models: Harris-Priester density model
  • Solar radiation pressure
  • Lambert Problem
  • Kepler Equation solver
  • Accurate orbit propagation
  • Integrators: fixed and adaptive step-size Runge-Kutta
  • JPL Ephemerides
  • Linear equation solver
  • Unconstrained optimization (BFGS)
  • Non-linear equation solvers, including Newton-Raphson and Regula Falsi
  • Linear Algebra (based on JAMA and JMAT)
  • Ground Tracks
  • 3-D Visualization for orbits and trajectories
  • GPS, INS and integrated GPS/INS simulation
     

Planned Features

  • Constrained nonlinear optimization
  • Gravity models: N-body
  • Orbit estimation: batch and Kalman filter methods
  • Trajectory optimization: Direct and indirect methods for continuous thrust
  • General Utility classes for optimal control using thrust vectors and state-space models
  • General Utility class for Mission Design with multiple maneuvers and launch windows
  • Flyby trajectory design
  • Genetic algorithm for optimization
  • N-body impulsive transfer problems.
  • Optimal attitude dynamics
  • Station-keeping
     

Licensing

            JAT is free software distributed under the terms of several licenses: See Licenses

Copyright (c) 2002  The JAT Project. All rights reserved.

 

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