Four space probes are spread evenly throughout the base exterior. Smash them for the shield piece.
Return to this base using Rex Fury. There are three super strength crates that only Rex can open. You can find these in the base exterior.
When you reach the loading bay, look for two safes. Open them to get a shield piece.
As the platform collapses, look for three small crates. Destroy them for the final piece.