/// <summary>
/// 计算绕地航天器主要的加速度。
/// Computes the acceleration of an Earth orbiting satellite due to
/// - the Earth's harmonic gravity field,
/// - the gravitational perturbations of the Sun and Moon
/// - the solar radiation pressure and
/// - the atmospheric drag
/// </summary>
/// <param name="Mjd_TT"> Mjd_TT Terrestrial Time (Modified Julian Date)</param>
/// <param name="satXyzIcrf"> r 卫星在国际天球参考框架的位置 Satellite position vector in the ICRF/EME2000 system</param>
/// <param name="satVelocityIcrf"> v 卫星在国际天球参考框架的速度 Satellite velocity vector in the ICRF/EME2000 system</param>
/// <param name="Area"> Area Cross-section </param>
/// <param name="mass"> mass 质量 Spacecraft mass</param>
/// <param name="solarRadiPresCoeff"> coefOfRadiation 光压系数 Radiation pressure coefficient</param>
/// <param name="atmDragCoefficient"> coefOfDrag 大气阻力系数 Drag coefficient</param>
/// <returns> Acceleration (a=d^2r/dt^2) in the ICRF/EME2000 system</returns>
public static Geo.Algorithm.Vector AccelerOfMainForces(double Mjd_TT, Geo.Algorithm.Vector satXyzIcrf, Geo.Algorithm.Vector satVelocityIcrf, double Area, double mass, double solarRadiPresCoeff, double atmDragCoefficient)
{
double Mjd_UT1;
Geo.Algorithm.Vector a = new Geo.Algorithm.Vector(3), r_Sun = new Geo.Algorithm.Vector(3), r_Moon = new Geo.Algorithm.Vector(3);
Matrix T = new Matrix(3, 3), E = new Matrix(3, 3);
// Acceleration due to harmonic gravity field
Mjd_UT1 = Mjd_TT;
T = IERS.NutMatrix(Mjd_TT) * IERS.PrecessionMatrix(MJD_J2000, Mjd_TT);
E = IERS.GreenwichHourAngleMatrix(Mjd_UT1) * T;
a = AccelerOfHarmonicGraviFiled(satXyzIcrf, E, Grav.GM, Grav.R_ref, Grav.CS, Grav.n_max, Grav.m_max);
// Luni-solar perturbations
r_Sun = CelestialUtil.Sun(Mjd_TT);
r_Moon = CelestialUtil.Moon(Mjd_TT);
a += AccelerOfPointMass(satXyzIcrf, r_Sun, OrbitConsts.GM_Sun);
a += AccelerOfPointMass(satXyzIcrf, r_Moon, OrbitConsts.GM_Moon);
// Solar radiation pressure
a += CelestialUtil.Illumination(satXyzIcrf, r_Sun) * AccelerOfSolarRadiPressure(satXyzIcrf, r_Sun, Area, mass, solarRadiPresCoeff, OrbitConsts.PressureOfSolarRadiationPerAU, AU);
// Atmospheric drag
a += AccelerDragOfAtmos(Mjd_TT, satXyzIcrf, satVelocityIcrf, T, Area, mass, atmDragCoefficient);
// Acceleration
return(a);
}
/// <summary>
/// Computes the acceleration of an Earth orbiting satellite due to
/// - the Earth's harmonic gravity field,
/// - the gravitational perturbations of the Sun and Moon
/// - the solar radiation pressure and
/// - the atmospheric drag
/// </summary>
/// <param name="Mjd_TT">Mjd_TT Terrestrial Time (Modified Julian Date)</param>
/// <param name="r">r Satellite position vector in the ICRF/EME2000 system</param>
/// <param name="v">v Satellite velocity vector in the ICRF/EME2000 system</param>
/// <param name="Area"> Area Cross-section </param>
/// <param name="mass"> mass Spacecraft mass</param>
/// <param name="coefOfRadiation">coefOfRadiation Radiation pressure coefficient</param>
/// <param name="coefOfDrag">coefOfDrag Drag coefficient</param>
/// <param name="n"></param>
/// <param name="m"></param>
/// <param name="isConsiderSun">是否启用太阳质量影响</param>
/// <param name="isConsiderMoon">是否启用月亮质量影响</param>
/// <param name="isConsiderSolarRadi">是否启用太阳光压影响</param>
/// <param name="isConsiderDrag">是否考虑大气影响</param>
/// <returns>Acceleration (a=d^2r/dt^2) in the ICRF/EME2000 system</returns>
public Geo.Algorithm.Vector GetAcceleration(double Mjd_TT, Geo.Algorithm.Vector r, Geo.Algorithm.Vector v)
{
// Acceleration due to harmonic gravity field
var Mjd_UT1 = Mjd_TT + (IERS.GetUT1_UTC(Mjd_TT) - IERS.GetTT_UTC(Mjd_TT)) / 86400.0;
var T = IERS.NutMatrix(Mjd_TT) * IERS.PrecessionMatrix(OrbitConsts.MJD_J2000, Mjd_TT);
var E = IERS.GreenwichHourAngleMatrix(Mjd_UT1) * T;
var a = Force.AccelerOfHarmonicGraviFiled(r, E, Force.Grav.GM, Force.Grav.R_ref, Force.Grav.CS, Option.MaxDegree, Option.MaxOrder);
// Luni-solar perturbations
var r_Sun = CelestialUtil.Sun(Mjd_TT);
if (Option.EnableSun)
{
a += Force.AccelerOfPointMass(r, r_Sun, OrbitConsts.GM_Sun);
}
if (Option.EnableMoon)
{
var r_Moon = CelestialUtil.Moon(Mjd_TT);
a += Force.AccelerOfPointMass(r, r_Moon, OrbitConsts.GM_Moon);
}
// Solar radiation pressure
if (Option.EnableSolarRadiation)
{
a += Force.AccelerOfSolarRadiPressure(r, r_Sun, Option.Area, Option.Mass, Option.CoefOfRadiation, OrbitConsts.PressureOfSolarRadiationPerAU, OrbitConsts.AU);
}
// Atmospheric drag
if (Option.EnableDrag)
{
a += Force.AccelerDragOfAtmos(Mjd_TT, r, v, T, Option.Area, Option.Mass, Option.CoefOfDrag);
}
// Acceleration
return(a);
}