third_body_gravity Subroutine

public subroutine third_body_gravity(r, rb, mu, acc)

Third-body (pointmass) gravitational acceleration.

Arguments

Type IntentOptional Attributes Name
real(kind=wp), intent(in), dimension(3) :: r

satellite position vector [km]
real(kind=wp), intent(in), dimension(3) :: rb

third-body position vector [km]
real(kind=wp), intent(in) :: mu

third-body gravitational parameter [km^3/s^2]
real(kind=wp), intent(out), dimension(3) :: acc

gravity acceleration vector [km/s^2]

Source Code

    subroutine third_body_gravity(r,rb,mu,acc)

    implicit none

    real(wp),dimension(3),intent(in)  :: r   !! satellite position vector [km]
    real(wp),dimension(3),intent(in)  :: rb  !! third-body position vector [km]
    real(wp),intent(in)               :: mu  !! third-body gravitational parameter [km^3/s^2]
    real(wp),dimension(3),intent(out) :: acc !! gravity acceleration vector [km/s^2]

    real(wp),dimension(3) :: r_sc_b  !! vector from third-body to spacecraft [km]
    real(wp) :: rb_mag               !! distance between origin and third-body [km]
    real(wp) :: r_sc_b_mag           !! distance between spacecraft and third-body [km]

    r_sc_b     = rb - r
    r_sc_b_mag = norm2(r_sc_b)
    rb_mag     = norm2(rb)
    acc        = (mu/r_sc_b_mag**3)*r_sc_b - (mu/rb_mag**3)*rb

    end subroutine third_body_gravity