Compact time-resolved remote Raman system for detection of anhydrous and hydrous minerals and ices for planetary exploration

Abstract

The University of Hawaii and NASA Langley Research Center are developing small, compact, and portable remote Raman systems with pulsed lasers for planetary exploration under the Mars Instrument Development Program. The remote Raman instruments developed previously utilized small telescopes with clear apertures of 125 mm and 100 mm diameters and were able to detect water, ice, water bearing minerals, carbon in carbonate form in calcite, magnesite, dolomite, and siderite from a distance of 10 to 50 m under daytime and nighttime conditions. Recently, we significantly reduced the size of our time-resolved (TR) remote Raman system in order to build a compact system suitable for future space missions. This compact time-resolved Raman system was developed by utilizing (i) a regular 85 mm Nikon (F/1.8) lens with a clear aperture of 50 mm as a collection optic, and (ii) a miniature Raman spectrograph that is 1/14^th in volume in comparison to the commercial spectrograph used in our previous work. In this paper, we present the TR remote Raman spectra obtained during daytime from various hydrous and anhydrous minerals, water, water-ice, and CO₂-ice using this new compact remote Raman system to 50 m radial distance.