NASA made good use of the vault within a vault. The outer vault was where the space agency kept archival materials, classified documents, and other papers that weren't meant to be released to the public. The inner vault was where they kept the materials that weren't even meant for people inside NASA. That's where the Apollo 1 tape was stored: the voices from the cockpit of the spacecraft when astronauts Gus Grissom, Ed White, and Roger Chaffee died in a fire on the launch pad on January 27, 1967.
Virtually no one ever heard the Apollo 1 tape until NASA ...
