MASS SPECTROMETER CALIBRATION OF CASSINI COSMIC DUST ANALYZER FOR METHANE ICE VIA LASER ABLATION

Introduction: The Cosmic Dust Analyzer (CDA) instrument aboard the Cassini spacecraft contains a time-of-flight mass spectrometer which will study the composition of dust particles in the vicinity of Saturn [1]. Dust particles impacting on the CDA instrument’s Chemical Analyzer Target generate ionized material which is accelerated via an electric field to a multiplier, with the arrival time of ion species at the multiplier being determined by their mass. The response of CDA to impacts of iron and carbon particles has been determined by experiment [2, 3]. However, no calibration data exists for particles consisting of planetary ices (e.g. CH4, NH3, H2O), which are expected to be encountered in the Saturnian system. We present results of experimental work in which laser ablation of a methane-coated mineral target is used to simulate the impact of methane ice particles onto the CDA instrument. Laser ablation was previously used to calibrate CDA for minerals [4, 5].