The alignment cubes you had activated previously have helped dampen the threat from White Doves, but many more cubes are required to reduce them to manageable numbers. Activate this second set of alignment cubes by pointing them away from Uranus to further hinder the White Doves.
The best approach is to determine in which direction an Alignment Cube is pointing, relative to Uranus, before you begin bumping them. All amplifiers in this mission are initially pointing toward Uranus, therefore you must bump each cube twice to point them away from Uranus. In order to orient yourself, use the marker rectangles to determine which side of the cubes you should bump. In the side-by-side yellow and blue tunnel systems initially visible from your starting point, bump each cube twice toward the edge closest to the marker rectangle (A). The other two Alignment Cubes are located in the spheres in the tunnel system behind your starting position. For the cube closer to the red entrance, bump it twice on the right (assuming the marker rectangle is visually on top, as in Fig. B), and for the cube closer to the yellow entrance, bump it twice on the left (again assuming the marker rectangle is on top, as in Fig. C).