/// <summary>
/// Currently this only calculates the change in velocity from 0 to planet radius +* 0.33333.
/// TODO: add gravity drag and atmosphere drag, and tech improvements for such.
/// </summary>
/// <param name="planetEntity"></param>
/// <param name="payload"></param>
/// <returns></returns>
public static double FuelCostToLowOrbit(Entity planetEntity, double payload)
{
var lowOrbit = LowOrbitRadius(planetEntity);
var exaustVelocity = 275;
var sgp = OrbitMath.CalculateStandardGravityParameter(payload, planetEntity.GetDataBlob <MassVolumeDB>().Mass);
Vector3 pos = new Vector3(lowOrbit, 0, 0);
var vel = OrbitMath.ObjectLocalVelocityPolar(sgp, pos, lowOrbit, 0, 0, 0);
var fuelCost = OrbitMath.TsiolkovskyFuelCost(payload, exaustVelocity, vel.speed);
return(fuelCost);
}