Laser time-of-flight mass spectrometry for space

We describe a miniature reflection time-of-flight mass spectrometer for in situ planetary surface analysis. The laser ablation mass spectrometer (LAMS ) measures the elemental and isotopic composition of regolith materials wit hout any sample preparation or high-voltage source extraction. The small si ze (< 2x10(3) cm(3)) and low mass (similar to 2 kg) of LAMS, due to its ful ly coaxial design and two-stage reflectron, satisfy the very strict resourc e limitations of landed science missions to solar system bodies. Microscopi c surface samples are obtained with a short-pulse laser focused to a spot w ith a diameter similar to 30-50 mu m. Coupled with a microimager, LAMS can interactively select and analyze a range of compositional regions (with lat eral motion) and access unweathered, subsurface materials (with repeated pu lses). The mass resolution is sufficient to distinguish isotopic peaks at u nit masses, and the detection limits are on the order of a few ppm. The des ign and calibration method of a prototype LAMS device is given, including t he development of preliminary relative sensitivity coefficients for major e lement bulk abundance measurements. (C) 2000 American Institute of Physics. [S0034-6748(00)00602-X].