Maxion Technologies and Physical Sciences Inc. (PSI) propose to jointly develop a compact, rugged, highly reliable, and autonomous sensor for in-situ monitoring of CO in spacecraft crew areas for fire warning. Our innovation is to combine a custom fabricated Quantum Cascade Laser (QCL) with PSI's proprietary single board electronics package that incorporates both a high sensitivity optical detection technique and all system control functions, to create a laser spectrometer for CO. The advent of QCLs enables the development of a very compact and highly sensitive monitor. This technical approach will result in a sensor that has the requisite dynamic range of 1 to 500 ppmv with a precision of 1 ppmv CO, in a physically robust and compact package. The Phase I program will demonstrate the feasibility of a breadboard sensor and create a detailed conceptual design for an advanced prototype. The TRL at the beginning of Phase I is level 2 and the TRL at the end of Phase I will be level 4. The Phase II program will fabricate a prototype that can be demonstrated at a relevant simulator. The TRL at the end of Phase II will be level 6. Successful completion of Phases I and II will result in a rigorously validated prototype sensor that can monitor ambient CO with high speed and precision. The sensor architecture can be easily modified to measure other species.