A boilerplate spacecraft, also known as a mass simulator, is a nonfunctional craft or payload that is used to test various configurations and basic size, load, and handling characteristics of rocket launch vehicles. 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. These tests may be used to develop procedures for mating a spacecraft to its launch vehicle, emergency access and egress, maintenance support activities, and various transportation processes.
The term boilerplate originated from the use of boilerplatesteel for the construction of test articles/mock-ups. Historically, during the development of the Little Joe series of 7 launch vehicles, there was only one actual boilerplate capsule and it was called such since its conical section was made of steel at the Norfolk Naval Shipyard. This capsule was used in a beach abort test, and then subsequently used in the LJ1A flight. However, the term subsequently came to be used for all the prototype capsules (which in their own right were nearly as complicated as the orbital capsules). This usage was technically incorrect, as those other capsules were not made of boilerplate, but the boilerplate term had effectively been genericized.
1959 July 22 - First successful pad abort flight test with a functional escape tower attached to a Mercury Boilerplate.
1959 July 28 - A Mercury boilerplate with instrumentation to measure sound pressure levels and vibrations from the Little Joe test rocket and Grand Central abort rocket/escape tower.
1959 September 9 - A Big Joe Atlas boilerplate Mercury (BJ-1) was successfully launched and flown from Cape Canaveral. This test flight was to determine the performance of the heat shield and heat transfer to the boilerplate, to observe flight dynamics of boilerplate during re-entry into the South Atlantic, to perform and evaluate capsule flotation and recovery system procedures, and to evaluate the entire capsule and rocket characters and system controls.