ST9Orbit:

% Simulate semi-major axis change in a dawn-dusk sun-synchronous orbit.
   Uses a simple specular model for the solar pressure force.
   Integration tolerance must be tight enough to produce circular
   precessing orbit when sail is edge-on.
   Multiple sail angle laws are implemented in the code. Scroll down to
   select a method or add your own.

   Default sail sizes are from 40 to 60 m square. The total spacecraft
   mass is on the order of 500 kg.

   If one axis of the sail is aligned with LVLH, which alleviates gravity
   gradient torques, the semi-major axis change is on the order of 40 km
   in 15 days. The sun-synch orbit is closely maintained.
   The oscillations in semi-major axis change are due to the inclusion of
   the J2 gravity term, which is necessary for a sun-synch orbit.

   Since version 7.
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  See also Inertias, Cone, Eul2Q, QLVLH, QMult, QTForm, NPlot, Plot2D, 
  TimeLabl, Cross, Dot, RK45, Unit, Date2JD, LoadGravityModel, El2RV, 
  PltOrbit, RV2El, Eclipse, SunV1, Accel, UToConeClock, delta
  ------------------------------------------------------------------------
%
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   Copyright (c) 2006 Princeton Satellite Systems, Inc.
   All rights reserved.
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Children:

AeroUtils: Coord/QLVLH
Common: Graphics/Plot2D
Common: Graphics/TimeLabl
Common: MassProperties/Inertias
Common: Quaternion/QMult
Common: Quaternion/QTForm
Common: Time/Date2JD
Common: Transform/Eul2Q
Math: Integration/RK45
Math: Linear/Cross
Math: Linear/Dot
Math: Linear/Unit
Orbit: GravityModels/LoadGravityModel
OrbitMiniToolbox: Support/El2RV
SC: BasicOrbit/PltOrbit
SC: BasicOrbit/RV2El
SC: Ephem/Eclipse
SC: Ephem/SunV1
Sail: Coordinates/UToConeClock