OrganiCam: a lightweight time-resolved laser-induced luminescence imager and Raman spectrometer for planetary organic material characterization.

OrganiCam is a laser-induced luminescence imager and spectrometer designed for standoff organic and biosignature detection on planetary bodies. OrganiCam uses a diffused laser beam (12° cone) to cover a large area at several meters distance and records luminescence on half of its intensified detector. The diffuser can be removed to record Raman and fluorescence spectra from a small spot from 2 m standoff distance. OrganiCam's small size and light weight makes it ideal for surveying organics on planetary surfaces. We have designed and built a brassboard version of the OrganiCam instrument and performed initial tests of the system.

Remote Raman spectroscopy of natural rocks.

We report the remote Raman spectra of natural igneous, metamorphic, and sedimentary rock samples at a standoff distance of 5 m. High-quality remote Raman spectra of unprepared rocks are necessary for accurate and realistic analysis of future Raman measurements on planetary surfaces such as Mars. Our results display the ability of a portable compact remote Raman system (CRRS) to effectively detect and isolate various light- and dark-colored mineral phases in natural rocks. The CRRS easily detected plagioclase and potassium feldspar end members, quartz, and calcite in rocks with high fluorescence backgrounds. Intermediate feldspars and quartz, when found in rocks with complex mineralogies, exhibited band shifts and broadening in the ${504{-}510}\,\,{{\rm cm}^{ - 1}}$504-510cm-1 and ${600{-}1200}\,\,{{\rm cm}^{ - 1}}$600-1200cm-1 regions. A good approximation of intermediate plagioclase feldspars was possible by using overall Raman spectral shape and assigning other minor Raman peaks in addition to the $ 504{-}510\,\,{{\rm cm}^{ - 1}}$504-510cm-1 peaks. Detection of olivine and pyroxene in mafic rocks allowed for compositional characterization.

Remote Raman measurements of minerals, organics, and inorganics at 430 m range.

Raman spectroscopy is a characterization technique that is able to analyze and detect water or water-bearing minerals, minerals, and organic materials that are of special interest for planetary science. Using a portable pulsed remote Raman system with a commercial 8 in. (203.2 mm) telescope, a frequency doubled Nd-YAG-pulsed laser, and a spectrometer equipped with an intensified CCD camera, we acquired good quality Raman spectra of various materials from a 430 m standoff distance during daylight with detection times of 1-10 s, in a realistic context in which both the exciting source and the detector are part of the same measurement system. Remote Raman spectra at this distance provided unambiguous detection of compounds such as water and water ice, dry ice, sulfur, sulfates, various minerals and organics, and atmospheric gases. This research work demonstrates significant improvement in the remote Raman technique as well as its suitability for solar system exploration.

Biofinder detects biological remains in Green River fish fossils from Eocene epoch at video speed.

The "Search for life", which may be extinct or extant on other planetary bodies is one of the major goals of NASA planetary exploration missions. Finding such evidence of biological residue in a vast planetary landscape is an enormous challenge. We have developed a highly sensitive instrument, the "Compact Color Biofinder", which can locate minute amounts of biological material in a large area at video speed from a standoff distance. Here we demonstrate the efficacy of the Biofinder to detect fossils that still possess strong bio-fluorescence signals from a collection of samples. Fluorescence images taken by the Biofinder instrument show that all Knightia spp. fish fossils analysed from the Green River formation (Eocene, 56.0-33.9 Mya) still contain considerable amounts of biological residues. The biofluorescence images support the fact that organic matter has been well preserved in the Green River formation, and thus, not diagenetically replaced (replaced by minerals) over such a significant timescale. We further corroborated results from the Biofinder fluorescence imagery through Raman and attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopies, scanning electron microscopy, energy dispersive X-ray spectroscopy (SEM-EDS), and fluorescence lifetime imaging microscopy (FLIM). Our findings confirm once more that biological residues can survive millions of years, and that using biofluorescence imaging effectively detects these trace residues in real time. We anticipate that fluorescence imaging will be critical in future NASA missions to detect organics and the existence of life on other planetary bodies.

Compositionally and density stratified igneous terrain in Jezero crater, Mars.

Before Perseverance, Jezero crater's floor was variably hypothesized to have a lacustrine, lava, volcanic airfall, or aeolian origin. SuperCam observations in the first 286 Mars days on Mars revealed a volcanic and intrusive terrain with compositional and density stratification. The dominant lithology along the traverse is basaltic, with plagioclase enrichment in stratigraphically higher locations. Stratigraphically lower, layered rocks are richer in normative pyroxene. The lowest observed unit has the highest inferred density and is olivine-rich with coarse (1.5 millimeters) euhedral, relatively unweathered grains, suggesting a cumulate origin. This is the first martian cumulate and shows similarities to martian meteorites, which also express olivine disequilibrium. Alteration materials including carbonates, sulfates, perchlorates, hydrated silicates, and iron oxides are pervasive but low in abundance, suggesting relatively brief lacustrine conditions. Orbital observations link the Jezero floor lithology to the broader Nili-Syrtis region, suggesting that density-driven compositional stratification is a regional characteristic.

Enhancement of the Anti-Stokes Fluorescence of Hollow Spherical Carbon Nitride Nanostructures by High Intensity Green Laser.

Fluorescence spectra of graphitic (g-C3N4) and spherical (s-C3N4) modifications of carbon nitride were measured as a function of green pulsed (6 ns-pulse) laser intensity. It was found that the intensity of the laser increases the maximum of the fluorescence shifts towards the anti-Stokes side of the fluorescence for s-C3N4 spherical nanoparticles. This phenomenon was not observed for g-C3N4 particles. The maximum of the anti-Stokes fluorescence in s-C3N4 nanoparticles was observed at 480 nm. The ratio of the intensity of the anti-Stokes peak (centered at 480 nm) to that of the Stokes peak (centered at 582 nm) was measured to be I484/582 = 6.4 × 10-3 at a low level of intensity (5 mW) of a green pulsed laser, whereas it rose to I484/582 = 2.27 with a high level of laser intensity (1500 mW).

Detecting Minerals and Organics Relevant to Planetary Exploration Using a Compact Portable Remote Raman System at 122 Meters.

Raman spectroscopy is a technique that can detect and characterize a range of molecular compounds such as water, water ice, water-bearing minerals, and organics of particular interest to planetary science. The detection and characterization of these molecular compounds, which are indications of habitability on planetary bodies, have become an important goal for planetary exploration missions spanning the solar system. Using a compact portable remote Raman system consisting of a 532 nm neodymium-doped yttrium aluminum garnet- (Nd:YAG-) pulsed laser, a 3-in. (7.62 cm) diameter mirror lens and a compact spectrograph with a miniature intensified charge coupled device (mini-ICCD), we were able to detect water (H2O), water ice (H2O-ice), CO2-ice, hydrous minerals, organics, nitrates, and an amino acid from a remote distance of 122 m in natural lighting conditions. To the best of our knowledge, this is the longest remote Raman detection using a compact system. The development of this uniquely compact portable remote Raman system is applicable to a range of solar system exploration missions including stationary landers for ocean worlds and lunar exploration, as they provide unambiguous detection of compounds indicative of life as well as resources necessary for further human exploration.

Underwater Time-Gated Standoff Raman Sensor for In Situ Chemical Sensing.

We describe the fabrication of an underwater time-gated standoff Raman sensor, consisting of a custom Raman spectrometer, custom scanner, and commercial diode-pumped pulsed 532 nm laser all located inside a pressure housing. The Raman sensor was tested in the laboratory with samples in air, a tank containing tap water and seawater, and in the coastal Hawaiian harbor. We demonstrate our new system by presenting standoff Raman spectra of some of the chemicals used in homemade explosive devices and improvised explosive devices, including sulfur, nitrates, chlorates, and perchlorates up to a distance of ∼6 m in seawater and tap water. Finally, the Raman spectra of these hazardous chemicals sealed inside plastic containers submersed in the Hawaiian Harbor water are also presented.

Compact Color Biofinder (CoCoBi): Fast, Standoff, Sensitive Detection of Biomolecules and Polyaromatic Hydrocarbons for the Detection of Life.

We have developed a compact instrument called the "COmpact COlor BIofinder", or CoCoBi, for the standoff detection of biological materials and organics with polyaromatic hydrocarbons (PAHs) using a nondestructive approach in a wide area. The CoCoBi system uses a compact solid state, conductively cooled neodymium-doped yttrium aluminum garnet (Nd:YAG) nanosecond pulsed laser capable of simultaneously providing two excitation wavelengths, 355 and 532 nm, and a compact, sensitive-gated color complementary metal-oxide-semiconductor camera detector. The system is compact, portable, and determines the location of biological materials and organics with PAHs in an area 1590 cm2 wide, from a target distance of 3 m through live video using fast fluorescence signals. The CoCoBi system is highly sensitive and capable of detecting a PAH concentration below 1 part per billion from a distance of 1 m. The color images provide the simultaneous detection of various objects in the target area using shades of color and morphological features. We demonstrate that this unique feature successfully detected the biological remains present in a 150-million-year-old fossil buried in a fluorescent clay matrix. The CoCoBi was also successfully field-tested in Hawaiian ocean water during daylight hours for the detection of natural biological materials present in the ocean. The wide-area and video-speed imaging capabilities of CoCoBi for biodetection may be highly useful in future NASA rover-lander life detection missions.

Remote Raman Detection of Chemicals from 1752 m During Afternoon Daylight.

The detection and identification of materials from a distance is highly desirable for applications where accessibility is limited or there are safety concerns. Raman spectroscopy can be performed remotely and provides a very high level of confidence in detection of chemicals through vibrational modes. However, the remote Raman detection of chemicals is challenging because of the very weak nature of Raman signals. Using a remote Raman system, we performed fast remote detection of various solid and liquid chemicals from 1752 m during afternoon hours on a sunny day in Hawaii. Remote Raman systems with kilometer target range could be useful for chemical detection of volcanic gases, methane clathrate icebergs or fire ice, toxic gas clouds and toxic waste, explosives, and hazardous chemicals. With this successful test, we demonstrate the feasibility of developing future mid-size remote Raman systems suitable for long range chemical detection using helicopters and light airplanes.

A Two Components Approach for Long Range Remote Raman and Laser-Induced Breakdown (LIBS) Spectroscopy Using Low Laser Pulse Energy.

The remote detection of chemicals using remote Raman spectroscopy and laser-induced breakdown spectroscopy (LIBS) is highly desirable for homeland security and NASA planetary exploration programs. We recently demonstrated Raman spectra with high signal-to-noise ratio of various materials from a 430 m distance during daylight with detection times of 1-10 s, utilizing a 203 mm diameter telescopic remote Raman system and 100 mJ/pulse laser energy at 532 nm for excitation. In this research effort, we describe a simple two-components approach that helps to obtain remote Raman and LIBS spectra of targets at distance of 246 m with 3 mJ/pulse in daytime. The two components of the method are: (1) a small spectroscopy system utilizing 76 mm diameter collection optics; and (2) a small remote lens near the target. Remote Raman spectra of various chemicals are presented here with detection time of 1 s. Remote LIBS spectra of minerals using single laser pulse of 3 mJ/pulse energy from a distance of 246 m are also presented. This research work demonstrates a simple approach that significantly improves remote Raman and LIBS capabilities for long range chemical detection with compact low laser power Raman and LIBS systems.

Remote Raman Efficiencies and Cross-Sections of Organic and Inorganic Chemicals.

We determined Raman cross-sections of various organic liquids and inorganic polyatomic ions in aqueous solutions with a 532 nm pulsed laser using remote Raman systems developed at the University of Hawaii. Using a calibrated integrating sphere as a light source, we converted the intensity counts in the spectrum of the light from the integrating sphere measured with UH remote Raman instrument to spectral radiance. From these data, a response function of the remote Raman instrument was obtained. With the intensity-calibrated instrument, we collected remote Raman data from a standard 1 mm path length fused silica spectrophotometer cell filled with cyclohexane. The measured value of the differential Raman cross-section for the 801 cm-1 vibrational mode of cyclohexane is 4.55 × 10-30 cm2 sr-1 molecule-1 when excited by a 532 nm laser, in good agreement with the values reported in the literature. Using the measured cyclohexane Raman cross-section as a reference and relative Raman mode intensities of the various ions and organic liquids, we calculated the Raman cross-sections of the strongest Raman lines of nitrate, sulfate, carbonate, phosphate ions, and organic liquids by maintaining same experimental conditions for remote Raman detection. These relative Raman cross-section values will be useful for estimating detection capabilities of remote Raman systems for planetary exploration.

"Standoff Biofinder" for Fast, Noncontact, Nondestructive, Large-Area Detection of Biological Materials for Planetary Exploration.

UNLABELLED: We developed a prototype instrument called the Standoff Biofinder, which can quickly locate biological material in a 500 cm(2) area from a 2 m standoff distance with a detection time of 0.1 s. All biogenic materials give strong fluorescence signals when excited with UV and visible lasers. In addition, the luminescence decay time of biogenic compounds is much shorter (<100 ns) than the micro- to millisecond decay time of transition metal ions and rare-earth ions in minerals and rocks. The Standoff Biofinder takes advantage of the short lifetime of biofluorescent materials to obtain real-time fluorescence images that show the locations of biological materials among luminescent minerals in a geological context. The Standoff Biofinder instrument will be useful for locating biological material during future NASA rover, lander, and crewed missions. Additionally, the instrument can be used for nondestructive detection of biological materials in unique samples, such as those obtained by sample return missions from the outer planets and asteroids. The Standoff Biofinder also has the capacity to detect microbes and bacteria on space instruments for planetary protection purposes. KEY WORDS: Standoff Biofinder-Luminescence-Time-resolved fluorescence-Biofluorescence-Planetary exploration-Planetary protection-Noncontact nondestructive biodetection. Astrobiology 16, 715-729.

Next generation laser-based standoff spectroscopy techniques for Mars exploration.

In the recent Mars 2020 Rover Science Definition Team Report, the National Aeronautics and Space Administration (NASA) has sought the capability to detect and identify elements, minerals, and most importantly, biosignatures, at fine scales for the preparation of a retrievable cache of samples. The current Mars rover, the Mars Science Laboratory Curiosity, has a remote laser-induced breakdown spectroscopy (LIBS) instrument, a type of quantitative elemental analysis, called the Chemistry Camera (ChemCam) that has shown that laser-induced spectroscopy instruments are not only feasible for space exploration, but are reliable and complementary to traditional elemental analysis instruments such as the Alpha Particle X-Ray Spectrometer. The superb track record of ChemCam has paved the way for other laser-induced spectroscopy instruments, such as Raman and fluorescence spectroscopy. We have developed a prototype remote LIBS-Raman-fluorescence instrument, Q-switched laser-induced time-resolved spectroscopy (QuaLITy), which is approximately 70 000 times more efficient at recording signals than a commercially available LIBS instrument. The increase in detection limits and sensitivity is due to our development of a directly coupled system, the use of an intensified charge-coupled device image detector, and a pulsed laser that allows for time-resolved measurements. We compare the LIBS capabilities of our system with an Ocean Optics spectrometer instrument at 7 m and 5 m distance. An increase in signal-to-noise ratio of at least an order of magnitude allows for greater quantitative analysis of the elements in a LIBS spectrum with 200-300 µm spatial resolution at 7 m, a Raman instrument capable of 1 mm spatial resolution at 3 m, and bioorganic fluorescence detection at longer distances. Thus, the new QuaLITy instrument fulfills all of the NASA expectations for proposed instruments.