Limit distance from center

The following code let's my ship move around a spherical world. It works great except when it collides with an collider. If head on it will float up into space.

How can I prevent this behavior? I tried clamping the magnitude and combining the resulting vector with a forwards vector and putting that into rigidBody.MovePosition, but that makes my ship immobile.

 using UnityEngine;
 
 using System.Collections;
 
 public class MovementTest : MonoBehaviour {
  
  [SerializeField]private float turnSpeed = 60;
  [SerializeField]private float forwardSpeed = 40;
  
  private Rigidbody mRigidBody;
  private float distance;
  // Use this for initialization
  void Start () {
  mRigidBody = rigidbody;
  distance = Vector3.Distance(mRigidBody.position, Vector3.zero);
  }
  
  void FixedUpdate () 
  {
  //Forward speed
  mRigidBody.velocity = transform.forward * Time.deltaTime * forwardSpeed;
  //Calculate the up vector
  Vector3 surfaceUp = mRigidBody.position - Vector3.zero;
  //Set the current rotation of the rigidBody
  Quaternion surfaceUpRotation = mRigidBody.rotation;
  //Set the angle to 90 degress
         surfaceUpRotation.SetLookRotation(surfaceUp, -transform.forward);
         surfaceUpRotation *= Quaternion.Euler(90,0,0);
  //get a rotation for steering
  Quaternion rot = Quaternion.identity;
  if(Input.GetKey(KeyCode.LeftArrow) )
  rot = Quaternion.Euler( transform.up * Time.deltaTime * -turnSpeed );
  else if(Input.GetKey(KeyCode.RightArrow))
  rot = Quaternion.Euler( transform.up * Time.deltaTime * turnSpeed );
  //multiply it with the surface rotation to add them.
  mRigidBody.MoveRotation( surfaceUpRotation * rot );
  }
 }