Optical fiber grating sensor network based on highly 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 2D 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 degree(s)C, have been fulfilled applying appropriate fiber passivation and Ormocer re-coating techniques, and by the development of a robust polychromator based signal processing unit.