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LOTOS Models

The following models are available within LOTOS and can be selected by the user:


  • Earth gravity field with zonal harmonics up to J6
  • DE405 ephemeris library
  • Analytic polynomial ephemerides for highest performance
  • Atmospheric drag with Jacchia-Bowman 2008 or exponential atmosphere model
  • Van-Allen belt integrated radiation flux
  • Third body perturbation from Sun, Moon and planets
  • Solar radiation pressure and solar wind

Attitude Controls

  • Unit vector components in inertial or local orbit frame (RTN)
  • Euler angles with throttle in inertial or local orbit frame (RTN)
  • Euler angle rates in inertial or local orbit frame (RTN)
  • Spacecraft body rates (6DoF)
  • Fully automatic initial guess generation with analytic laws or from external file (either control history or trajectory)


  • Mass and moments of inertia
  • Power model incl. battery
  • Propulsion parameters (Isp, Thrust) as function of power
  • Propulsion time schedule (e.g. inactive on weekends)
  • Propulsion shut-off during eclipses
  • Thruster firing limitations (e.g. min./max. duration)
  • Thruster on-off mode (bang-bang control)
  • Disturbances of thrust direction and magnitude for robustness analysis
  • Attitude and slew rate limitations
  • Wheel momentum and torque
  • Star tracker with boresight direction and field of view
  • Reference area, drag coefficient and reflectivity index


  • Time or equinoctial element L as independent variable
  • Normalized or un-normalized independent variable
  • Equations of Motion based on equinoctial elements
  • Additional states: battery capacity, dwell time radiation belt, radiation dose, spacecraft attitude
  • Several ODE solvers:
    • Variable step-size solver Runge-Kutta 4/5
    • Variable step-size solver Runge-Kutta 7/8
    • Fixed step-size solver Runge-Kutte 4
    • Variable step-size solver MEBDFDAE