Remote Detection of Minerals and Biomarkers Using Rallf: a Compact Raman, Atmospheric Lidar, Libs and Fluorescence Sensor

Overview: University of Hawaii (UH) in collaboration with NASA Langley Research Center has developed a compact portable sensor platform capable of performing remote Raman, LIBS, Fluorescence and lidar measurements from stand-off distances. The system using a 2.5 inch diameter telescope is capable of measuring Raman, LIBS, and fluorescence spectra of a mineral target from a distance of several meters with single laser shot excitation using a 532 nm, 30 mJ/pulse, 20 Hz laser. High quality Raman spectra providing unambiguous identification of various minerals and organics from 9 m distance in daytime can be recorded with 100 ns detection time. Similarly, the system is capable of recording LIBS and time-resolved fluorescence spectra using single laser shots. The spectra measured with 1 s integration time (= 20 laser shots) show significant improvement in signal to noise and provide very high quality spectra. The system also has lidar capability for atmospheric studies. The combined spectroscopy system has the advantage of rapid mineral analysis from a long stand-off distance without need for sample collection or preparation, and thus could be a technology appropriate for future Mars landers. Among the various techniques for detecting water, ice, H2O/OH bearing minerals and biominerals, Raman spectroscopy stands out as providing distinctive spectra for unambiguous identification of water and waterbearing minerals. The portable remote Raman instrument developed at UH has been shown earlier to detect water, ice, water-bearing minerals, and carbon in carbonate form from a distance of 10 to 50 m under bright day conditions with short integration time [1-4]. Over the years we have demonstrated that a large number of minerals including dark minerals such as augite, actinolite, antigorite, dravite, clinochlore, olivine, and minerals in Hawaiian basaltic rocks can be easily detected using our compact remote Raman systems [5]. We have previously demonstrated [6-8] that it is possible to combine both stand-off Raman and LIBS spectroscopy into one system that will produce and record Raman and LIBS spectra from a single sample at a distance. The synergy of combined stand-off Raman and LIBS technique provides a very powerful analytical instrument for planetary surface exploration. In addition, the combined Raman and LIBS system also has the capability to perform time-resolved fluorescence spectroscopy. We have recently demonstrated that a new instrument known as “Stand-off Biofinder” can easily identify a biological material in a large search area in real time using time resolved fluorescence signals [9]. The task of finding a small