Definitions for "SMEX"
Small Explorer, or SMEX is a small-sized (defined by definition and development costs not exceeding $71M) spacecraft that carries one or more science instruments. Compare to MIDEX and UNEX; see also Explorer.
Simple Messaging Extension. The communication mechanism by which SALT applications establish an asynchronous message exchange channel for sending and receiving messages between the SALT application and external components of the SALT platform.