Virtual Instrumentation Engineering Workbench is a commercial tool which is being used to simulate the spacecraft subsystems during initial development and will also be used during flight to test software on the ground before it is migrated to the flight system. As each subsystem design progresses, its functionality is imitated in LabVIEW. Utilizing a sockets connection, SCL queries LabVIEW for the current state of each subsystem, much like it will be utilized to query the real instruments during flight. As each subsystem is prototyped, its hardware replaces its respective LabVIEW simulation, until at last the complete spacecraft is integrated. During flight, the ground system software will test new command software using the LabVIEW hardware simulation. Once the code is validated, it will then be migrated to the embedded system on the shuttle.