public static Vector3d DeltaVAndTimeForCheapestCourseCorrection(Orbit o, double UT, Orbit target, CelestialBody targetBody, double finalPeR, out double burnUT)
{
Vector3d collisionDV = DeltaVAndTimeForCheapestCourseCorrection(o, UT, target, out burnUT);
Orbit collisionOrbit = o.PerturbedOrbit(burnUT, collisionDV);
double collisionUT = collisionOrbit.NextClosestApproachTime(target, burnUT);
Vector3d collisionPosition = target.SwappedAbsolutePositionAtUT(collisionUT);
Vector3d collisionRelVel = collisionOrbit.SwappedOrbitalVelocityAtUT(collisionUT) - target.SwappedOrbitalVelocityAtUT(collisionUT);
double soiEnterUT = collisionUT - targetBody.sphereOfInfluence / collisionRelVel.magnitude;
Vector3d soiEnterRelVel = collisionOrbit.SwappedOrbitalVelocityAtUT(soiEnterUT) - target.SwappedOrbitalVelocityAtUT(soiEnterUT);
double E = 0.5 * soiEnterRelVel.sqrMagnitude - targetBody.gravParameter / targetBody.sphereOfInfluence; //total orbital energy on SoI enter
double finalPeSpeed = Math.Sqrt(2 * (E + targetBody.gravParameter / finalPeR)); //conservation of energy gives the orbital speed at finalPeR.
double desiredImpactParameter = finalPeR * finalPeSpeed / soiEnterRelVel.magnitude; //conservation of angular momentum gives the required impact parameter
Vector3d displacementDir = Vector3d.Cross(collisionRelVel, o.SwappedOrbitNormal()).normalized;
Vector3d interceptTarget = collisionPosition + desiredImpactParameter * displacementDir;
Vector3d velAfterBurn;
Vector3d arrivalVel;
LambertSolver.Solve(o.SwappedRelativePositionAtUT(burnUT), interceptTarget - o.referenceBody.position, collisionUT - burnUT, o.referenceBody, true, out velAfterBurn, out arrivalVel);
Vector3d deltaV = velAfterBurn - o.SwappedOrbitalVelocityAtUT(burnUT);
return(deltaV);
}
void ComputeDeltaV(object args)
{
CelestialBody origin_planet = origin.referenceBody;
for (int date_index = TakeDateIndex();
date_index >= 0;
date_index = TakeDateIndex())
{
double t0 = DateFromIndex(date_index);
Vector3d V1_0 = origin_planet.orbit.getOrbitalVelocityAtUT(t0);
Vector3d R1 = origin_planet.orbit.getRelativePositionAtUT(t0);
int duration_samples = DurationSamplesForDate(date_index);
for (int duration_index = 0; duration_index < duration_samples; duration_index++)
{
if (stop)
{
break;
}
double dt = DurationFromIndex(duration_index);
double t1 = t0 + dt;
Vector3d R2 = destination.getRelativePositionAtUT(t1);
bool short_way = Vector3d.Dot(Vector3d.Cross(R1, R2), origin_planet.orbit.GetOrbitNormal()) > 0;
try
{
Vector3d V1, V2;
#if DEBUG
log[date_index, duration_index] = dt + ","
+ R1.x + "," + R1.y + "," + R1.z + ","
+ R2.x + "," + R2.y + "," + R2.z + ","
+ V1_0.x + "," + V1_0.y + "," + V1_0.z;
#endif
LambertSolver.Solve(R1, R2, dt, origin_planet.referenceBody, short_way, out V1, out V2);
#if DEBUG
log[date_index, duration_index] += "," + V1.x + "," + V1.y + "," + V1.z;
#endif
Vector3d soi_exit_velocity = V1 - V1_0;
var maneuver = ComputeEjectionManeuver(soi_exit_velocity, origin, t0);
if (!double.IsNaN(maneuver.dV.sqrMagnitude) && !double.IsNaN(maneuver.UT))
{
computed[date_index, duration_index] = maneuver;
}
#if DEBUG
log[date_index, duration_index] += "," + maneuver.dV.magnitude;
#endif
}
catch (Exception) {}
}
}
JobFinished();
}
public static Vector3d DeltaVAndTimeForCheapestCourseCorrection(Orbit o, double UT, Orbit target, double caDistance, out double burnUT)
{
Vector3d collisionDV = DeltaVAndTimeForCheapestCourseCorrection(o, UT, target, out burnUT);
Orbit collisionOrbit = o.PerturbedOrbit(burnUT, collisionDV);
double collisionUT = collisionOrbit.NextClosestApproachTime(target, burnUT);
Vector3d position = o.SwappedAbsolutePositionAtUT(collisionUT);
Vector3d targetPos = target.SwappedAbsolutePositionAtUT(collisionUT);
Vector3d direction = targetPos - position;
Vector3d interceptTarget = targetPos + target.NormalPlus(collisionUT) * caDistance;
Vector3d velAfterBurn;
Vector3d arrivalVel;
LambertSolver.Solve(o.SwappedRelativePositionAtUT(burnUT), interceptTarget - o.referenceBody.position, collisionUT - burnUT, o.referenceBody, true, out velAfterBurn, out arrivalVel);
Vector3d deltaV = velAfterBurn - o.SwappedOrbitalVelocityAtUT(burnUT);
return(deltaV);
}
//Computes the delta-V of a burn at a given time that will put an object with a given orbit on a
//course to intercept a target at a specific interceptUT.
public static Vector3d DeltaVToInterceptAtTime(Orbit o, double UT, Orbit target, double interceptUT, double leadDistance = 0)
{
double initialT = UT;
Vector3d initialRelPos = o.SwappedRelativePositionAtUT(initialT);
double finalT = interceptUT;
Vector3d finalRelPos = target.SwappedRelativePositionAtUT(finalT);
finalRelPos += leadDistance * target.SwappedOrbitalVelocityAtUT(finalT).normalized;
double targetOrbitalSpeed = o.SwappedOrbitalVelocityAtUT(finalT).magnitude;
double deltaTPrecision = 20.0 / targetOrbitalSpeed;
Vector3d initialVelocity, finalVelocity;
LambertSolver.Solve(initialRelPos, finalRelPos, finalT - initialT, o.referenceBody, true, out initialVelocity, out finalVelocity);
Vector3d currentInitialVelocity = o.SwappedOrbitalVelocityAtUT(initialT);
return(initialVelocity - currentInitialVelocity);
}
//Computes the delta-V of a burn at a given time that will put an object with a given orbit on a
//course to intercept a target at a specific interceptUT.
public static Vector3d DeltaVToInterceptAtTime(Orbit o, double UT, Orbit target, double interceptUT, double offsetDistance = 0, bool shortway = true)
{
double initialT = UT;
Vector3d initialRelPos = o.SwappedRelativePositionAtUT(initialT);
double finalT = interceptUT;
Vector3d finalRelPos = target.SwappedRelativePositionAtUT(finalT);
Vector3d initialVelocity, finalVelocity;
LambertSolver.Solve(initialRelPos, finalRelPos, finalT - initialT, o.referenceBody, shortway, out initialVelocity, out finalVelocity);
if (offsetDistance != 0)
{
finalRelPos += offsetDistance * Vector3d.Cross(finalVelocity, finalRelPos).normalized;
LambertSolver.Solve(initialRelPos, finalRelPos, finalT - initialT, o.referenceBody, shortway, out initialVelocity, out finalVelocity);
}
Vector3d currentInitialVelocity = o.SwappedOrbitalVelocityAtUT(initialT);
return(initialVelocity - currentInitialVelocity);
}
