P044-0006
In situ Chemistry Experiment – μscope, Photoluminescence and Raman OBservations on Europa (ICE-μPROBE)

Friday, 11 December 2020
Poster
Shahid Aslam, NASA Goddard Space Flight Center, Greenbelt, MD, United States, Dina M Bower, University of Maryland College Park, College Park, MD, United States, Nicolas Gorius, Catholic University of America, Washington, DC, United States, Tilak Hewagama, NASA Goddard Space Flight Center, Detector Systems Branch, Greenbelt, MD, United States, Steven Li, NASA Goddard Space Flight Center, Laser Branch, Greenbelt, United States and Shiv K Sharma, Univ Hawaii, Honolulu, HI, United States
Abstract:
We present an In situ Chemistry Experiment - µscope, Photoluminescence and Raman OBservations on Europa (ICE-µPROBE) instrument that will address 10 of the 23 science investigations in the Science Traceability Matrix (STM) of the Europa Lander Study 2016 Report and updated science goals, as recommended by the Science Definition Team. To do this, the instrument will carry out time-resolved Raman and photoluminescence (PL) spectroscopy, of ice samples collected from the surface to ~10 cm below the surface, to discover, if present, the types and distribution of biotic and abiotic organic compounds, measure CHNOPS containing organics and minerals and correlate them to radiolysis processed and textural features. Our instrument includes an optical microscope to provide context imaging for the spectroscopy.

ICE-µPROBE is a versatile, time resolved PL and Raman instrument package that is made up of a number of key assemblies as shown in Fig. 1, designed to survive the harsh Europa environment. Fig. 2 shows a system block diagram of the instrument. The microscope reflective objective (infinite conjugate) geometric ètendue (AΩ), of the Optical Head Assembly, determines the amount of backscattered PL and Raman light collected, when the sample is excited by either 266 nm or 532 nm light, and is a function of the sample emitting area and the solid angle into which it propagates; it is the limiting function of the optical system throughput. The instrument design ensures that AΩ is conserved in two parts, i.e., optical train from objective to (i) microscope; and (ii) an all reflective Offner type spectrometer (chosen because refractive spectrometers are more prone to radiation damage), this ensures maximum flux (photons/s) to the microscope camera (MicroCAM) that uses a radiation hard CMOS imager. The spectrometer camera (SpectraCam) uses a radiation hard intensified (multi-channel plate) CMOS imager. The spectrometer performance, in particular spectral resolution, is optimized by several factors, the focal length, diffraction grating line density, excitation laser wavelength, order sorting filters and the intensifier photocathode spatial resolution.

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