Blast Shield

Blast Shields are shields or locks placed over doors. They appear throughout the Metroid Series. They are completley invulnerable to any weapons fire. They are commonly used to contain enemy or other threats and do not open until the threat is removed, and sometimes are permanently shut. They are also known as Sealed Doors.

Other kinds of Blast Shield also appear in the Prime Trilogy. The Red Blast Shield is made of a weaker material and can be destroyed by Missiles. Green Blast Shields can be destroyed by Super Missiles, Power Bombs can destroy Yellow Blast Shields and Ice Missiles can remove White Blast Shields.

Samus Aran's Gunship also has a Blast Shield in Metroid Prime 3: Corruption, which is activated from the inside: "Blast Shield switch will engage a protective layer of armor around the cockpit."

Logbook entry
Metroid Prime 3: Corruption: "Blast Shields are invulnerable to all types of weapon fire. Some are engaged when hostiles are detected and will only open once the threat has been eliminated. Others will sometimes remain shut and force you to find an alternative route."