Vescent Photonics propose to develop a chip-sized narrow linewidth (< 50 kHz), widely tunable (> 10 nm's) diode laser that will be suitable for a wide variety of NASA remote sensing missions. The proposed laser platform enables easy selection of the laser center wavelength; these lasers can be easily built for any wavelength that a diode laser gain chip exists (< 670 nm to > 2.5 microns). Since spectral features of important molecular species cover a large wavelength window this center-wavelength flexibility is advantageous. This effort will focus on lasers operating in the 1.57 and 2.0 micron CO2 band, and the 1.26 micron O2 band, such as is required for ASCENDS-type missions. Rapid wide wavelength tunability will enable scans over large portions of spectral bands, which can minimize the impact of contaminant and thermal effects on total column density measurement. These lasers will provide for very fast phase (up to 10 GHz) modulation and be built with space qualifiable components. Collaborative relationships with established aerospace companies will be exploited to facilitate insertion of this technology into NASA missions.