In this SBIR Phase I effort, Los Gatos Research (LGR) proposes to develop novel instrumentation based on laser absorption spectroscopy techniques for ultrasensitive measurements of atomic and molecular concentrations as well as gas temperature and velocity in high enthalpy flows. These autonomous instruments, based on high resolution laser absorption spectroscopy, will provide highly accurate, real-time quantification of several important species and thus enable the validation and refinement of numerical physical and chemical kinetic models, facilities diagnostics, and eventual development of next-generation components and propulsion systems. In Phase I, the instrument will be fabricated and tested at LGR prior to integration onto a ground-based high enthalpy test facility at NASA Ames. The system will then be refined and delivered to a NASA test site. Final Phase I work will involve developing a Phase II prototype capable of making in situ measurements of multiple parameters in aerothermodynamics test facilities.