Unique environmental test requirements for atomic frequency standards for space applications

Unique tests and considerations are required for the space qualification of atomic frequency standards (AFS). AFSs have several advantages (i.e., low drift rate and inherent insensitivity to radiation) over more conventional crystal oscillators, which make them preferred for specialized space applications. These features allow the users to obtain more precision in navigation, timing and for autonomous operation. AFSs are exposed to the usual battery of qualification tests normally prescribed for other flight hardware, but their responses to these environments may be unique. There are several additional tests, not applicable to most electronic hardware, that are required for AFS. These test environments are described and applied to the most desired capability of AFS: frequency stability.