Ablative Armor
From Starbase 900 Wiki
Hull armor employed for the most recent Starfleet vessels such as the Defiant class and the U.S.S. Prometheus. It is an completely new armor design. The primary hull is shielded by a secondary armor consisting of small neutronium plates. If one of these plates is hit it is destroyed and falls away from the armor plating. By this the primary hull stays intact and the energy of the hit is absorbed by the armor whilst the armor plates behind the destroyed one stays intact. This allows the ship in question to survive massive weapons fire. Ablative armor will be used in most of the upcoming ship designs.