NASA SSTD-8070-0071-PRESSUR Rev. A, Standard for Breaking Vacuum in the Annular Space of Dewar Type Cryogenic Vessels, Revision (20-08-15). Active. Scope: This John C. Stennis Space Center (SSC) standard (SSTD) establishes criteria and general requirements which shall be included in any procedure and work authorizing document (WAD) for breaking the vacuum in the annular space of dewar type vessels. Public Access. SSC.