Photogrammetry for JWST
Photogrammetry (PG) is a method of metrology that utilizes photography to measure distance. The IDG developed two photogrammetry (PG) systems for JWST: one for ISIM testing at NASA Goddard Space Flight Center, and one for the end-to-end optical test at NASA Johnson Space Center. The NASA Goddard system was used to verify the structural/thermal behavior of the composite struture that houses the JWST instrumentation, the Integrated Science Instrument Module (ISIM). The NASA Johnson system was used to verify alignment between JWST and the optical metrology system suspended above it in Chamber A at Johnson Space Center. Both photogrammetry systems are engineered to operate in conditions that emulate the environment in space, i.e. vacuum and low temperature (~ -250°C).
JWST photogrammetry at NASA Goddard Space Flight Center. Photograph courtesy of NASA photographer Chris Gunn
Video of the ISIM testing at the Goddard Space Flight Center.
Photogrammetry at Johnson Space Center
Photogrammetry (PG) is a method of creating accurate three dimensional position measurements utilizing photography. For JWST, the technique was used to assess the as-built tolerances of complex assemblies and structures, including the telescope itself. Shown below are renderings of the key subsystems that make up the cryogenic photogrammetry system at Johnson Space Center.
