Aerodyne Research, Inc. and the University of Massachusetts at Amherst will collaborate to develop laser desorption ionization (LDI) mass spectrometric analysis of organic analytes of interest in planetary exploration, based on microchip laser illumination. The key advantage of microchip lasers in this application is their much smaller size and weight than lasers used to date for LDI. These lasers have not been used because they have much smaller pulse energies than currently used LDI lasers. We propose to investigate the use of LDI substrates with special properties that include lowering the laser fluence required for LDI. Our Phase I candidate substrate will be gold nanoparticles coated with functionalized monolayers. Coated nanoparticles have been shown to have significant advantages in LDI applications, including selectivity of analyte adsorption, and enhancement of desorption via surface plasmon resonance (SPR) effects.