Optical fiber grating sensor network basing on high-reliable fibers and components for spacecraft health monitoring

A fiber Bragg grating (FBG) sensor network has been developed for structural health monitoring on board of the X-38 spacecraft, the prototype of a crew return vehicle for the International Space Station. The FBG sensors will monitor mechanical and thermal load profiles of a frame component during launch and re-entry of the spacecraft. Four sensor pads are interrogated which contain three Bragg gratings each for 2-dimensional orthogonal strain and temperature measurements. The requirements for mechanical and thermal stability under the demanding conditions of vibration and shock loads, at temperatures within -40..+200 degreesC, have been fulfilled applying appropriate fiber passivation and Ormocer re-coating techniques, and by the development of a robust polychromator based signal processing unit.