TVE (Thrusted Vector Experiment), a.k.a. Delta 181, was the second Delta / SDI mission. Delta 181 involved the placement of a Delta second stage in low-Earth orbit, but it included the deployment of two payloads as the object of a series of experiments in orbit. One of the payloads was a plume generator package (SPX) with a Star-13A motor, and the other was a science package containing eight test objects and four reference objects. A sensor module, consisting of a command and data handling system and seven scientific experiments, remained with the Delta's second stage to scan elements of both packages once they were deployed.