The Nebula Class was designed with an emphasis on flexibility.  This is made possible by the raised equipment pod, which can be easily modified to carry scientific or tactical equipment pallets, or a combination of both configurations.  Fifty three vessels are in service as of 2376, and an open ended construction contract still on the table at the Utopia Yards.  Though categorized as an Explorer, the Nebula Class can excel at virtually an task Operations can think of, from limited survey missions to deep strike missions into the Dominion Alliance.