Launch Cavity Ringdown Spectroscopy from Earth to Space

Cavity ringdown spectroscopy and its associated techniques have been widely implemented for measurement, monitoring, and sensing in many applications in diverse fields, including energy, medicine, materials, environment, infrastructure, etc. Cavity ringdown technique has not been actually extended beyond its applications on Earth to new applications in space although ringdown instruments have been loaded to an aircraft to conduct real-time survey of atmospheric species. In addition to gas sensing, recent developments have advanced ringdown techniques for physical sensor developments by using a section of optical fiber as a conceptual high-reflectivity cavity without sacrificing the intrinsic natures of ringdown: near-real time response, high sensitivity, and measuring time constants to sense a quantity. Cavity ringdown has great potential to help address three significant issues in sensing applications associated with space science and engineering: time, logistics, and intelligence. The purpose of this paper is to introduce cavity ringdown to a new community: intelligent sensors for space science and engineering and to explore new applications, e.g., light-weight, multi-function, intelligent sensors for space vehicle structure health morning and control, real-time chemical sensors for methane, carbon dioxide, water, and carbon isotopes for extraterrestrial life exploration, and medical sensors for astronauts' metabolic status monitoring.