Test article (aerospace)

The Pathfinder for the James Webb Space Telescope shown here with extra mirrors on a non-flight test unit of the backplane

A test article or pathfinder is a version of a spacecraft or related vehicle or equipment, built as a platform to perform testing on particular portions of a spaceflight regime. Test articles are built to the specifications necessary to replicate particular conditions and behaviors that are to be validated. Test articles may be built for flight testing or for non-flight testing.

For space agencies with extensive flight certification procedures, they may be built without the certification and quality control steps taken with the versions intended for flight. Test articles are more complete than a boilerplate.