code: function addAsteroids() {
      while (asteroidBodies.length) {
        var asteroidBody = asteroidBodies.shift();
        world.destroyBody(asteroidBody);
        // asteroidBody.uiRemove();
      }
  
      for (var i = 0; i < level; i++) {
        var shipPosition = shipBody.getPosition();
        var x = shipPosition.x;
        var y = shipPosition.y;
  
        // Aviod the ship!
        while (Math.abs(x - shipPosition.x) < asteroidRadius * 2
            && Math.abs(y - shipPosition.y) < asteroidRadius * 2) {
          x = rand(SPACE_WIDTH);
          y = rand(SPACE_HEIGHT);
        }
  
        var vx = rand(asteroidSpeed);
        var vy = rand(asteroidSpeed);
        var va = rand(asteroidSpeed);
  
        // Create asteroid body
        var asteroidBody = makeAsteroidBody(x, y, vx, vy, va, 0);
        asteroidBody.level = 1;
      }
    }
docs: Adds some asteroids to the scene.