$LastChangedDate: 27-Juil-2011 $

# CL_ip_sphereInfluence

Computation of the sphere of influence

## Calling Sequence

       [rsoi1] = CL_ip_sphereInfluence(mu1,mu2,dist)

## Description

- Computes the radius of the sphere of influence around one celestial body.

  The sphere of influence (SOI) is the spherical region around a celestial body where the gravitational effect of other bodies can be neglected.

  This is usually used to describe the area around planets in the solar system where it is possible to neglect the gravitational effect of the Sun (the patched conics simplified approach assumes that the orbits are ellipses within the SOI, and hyperbolas outside the SOI).

## Parameters

mu1:

  gravitational constant of the first body [km^3/s^2] (1xN or 1x1)

mu2:

  gravitational constant of the second body [km^3/s^2] (1xN or 1x1)

dist:

  distance between the two bodies [m] (1xN or 1x1)

rsoi1:

  radius of sphere of influence around body 1 [m] (1xN)

## Authors

- CNES - DCT/SB

## Bibliography

- 1) Mecanique spatiale, CNES - Cepadues 1995, Tome II, chapter 18

## Examples

    // NOTA: Use CL_init to have access to CelestLab constants.

    // Example 1: Sphere of influence of the Earth
    mu1 = %CL_planetC.earth.mu;
    mu2 = %CL_muSun;
    dist = 1 * %CL_au;
    [rsoi1]=CL_ip_sphereInfluence(mu1,mu2,dist)

    // Example 2: Sphere of influence of the planets in the Solar system
    mu1 = [%CL_planetC.mercury.mu, %CL_planetC.venus.mu, %CL_planetC.earth.mu,..
    %CL_planetC.mars.mu, %CL_planetC.jupiter.mu, %CL_planetC.saturn.mu,..
    %CL_planetC.uranus.mu, %CL_planetC.neptune.mu];
    mu2 = %CL_muSun;
    dist = [0.39, 073, 1, 1.52, 5.2, 9.5, 19.2, 30.7] * %CL_au;
    [rsoi1] = CL_ip_sphereInfluence(mu1,mu2,dist)