The term boilerplate in rocketry refers to a nonfunctional craft, system, or payload which is used to test various configurations and basic size, load, and handling characteristics. It is far less expensive to build multiple, full-scale, non-functional boilerplate spacecraft than it is to develop the full system (design, test, redesign, and launch). In this way, boilerplate spacecraft allow components and aspects of cutting-edge aerospace projects to be tested while detailed contracts for the final project are being negotiated. During these tests, procedures are developed in mating boilerplates to rocket launch vehicles along with emergency access and egress, maintenance support activities, and various transportation processes.
Boilerplate spacecraft are most commonly used to test manned spacecraft; for example, in the early 1960s, NASA performed many tests of boilerplates. Such boilerplates were made for Apollo spacecraft atop Saturn I rockets, and Mercury spacecraft atop Atlas rockets (for example Big Joe 1). Space Shuttle Enterprise was used as both a ground test boilerplate spacecraft and an atmospheric flight test vehicle. The development of NASA's Project Constellation used boilerplate Orion spacecraft atop an Ares I rocket for initial testing.