Trace species measurement on unmanned atmospheric research craft suitable for interplanetary travel is a demanding application for optical sensing techniques. Yet optical techniques offer many advantages including high-precision, fast response, and strong species selectivity. Balloonsonde, kite, unmanned aerial vehicle (UAV), or glider deployment demands that optical sensors meet stringent size, weight and power requirements. Vista Photonics proposes to develop rugged, compact, battery-powered optical sensor technology capable of selectively determining humidity to 10 parts-per-billion (-100 o
C frost point). The enabling technology for meeting stringent NASA mission requirements is a new rugged, compact, and lightweight optical path length enhancement cell that recovers the theoretical sensitivity of established high-performance optical absorption detection techniques. The proposed spectrometer will be capable of detecting multiple species while incurring little additional weight or power penalties.