Perseverance’s Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) Investigation

Abstract

The Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) is a robotic arm-mounted instrument on NASA’s Perseverance rover. SHERLOC has two primary boresights. The Spectroscopy boresight generates spatially resolved chemical maps using fluorescence and Raman spectroscopy coupled to microscopic images (10.1 μm/pixel). The second boresight is a Wide Angle Topographic Sensor for Operations and eNgineering (WATSON); a copy of the Mars Science Laboratory (MSL) Mars Hand Lens Imager (MAHLI) that obtains color images from microscopic scales (∼13 μm/pixel) to infinity. SHERLOC Spectroscopy focuses a 40 μs pulsed deep UV neon-copper laser (248.6 nm), to a ∼100 μm spot on a target at a working distance of ∼48 mm. Fluorescence emissions from organics, and Raman scattered photons from organics and minerals, are spectrally resolved with a single diffractive grating spectrograph with a spectral range of 250 to ∼370 nm. Because the fluorescence and Raman regions are naturally separated with deep UV excitation (<250 nm), the Raman region ∼ 800 – 4000 cm−1 (250 to 273 nm) and the fluorescence region (274 to ∼370 nm) are acquired simultaneously without time gating or additional mechanisms. SHERLOC science begins by using an Autofocus Context Imager (ACI) to obtain target focus and acquire 10.1 μm/pixel greyscale images. Chemical maps of organic and mineral signatures are acquired by the orchestration of an internal scanning mirror that moves the focused laser spot across discrete points on the target surface where spectra are captured on the spectrometer detector. ACI images and chemical maps (< 100 μm/mapping pixel) will enable the first Mars in situ view of the spatial distribution and interaction between organics, minerals, and chemicals important to the assessment of potential biogenicity (containing CHNOPS). Single robotic arm placement chemical maps can cover areas up to 7x7 mm in area and, with the < 10 min acquisition time per map, larger mosaics are possible with arm movements. This microscopic view of the organic geochemistry of a target at the Perseverance field site, when combined with the other instruments, such as Mastcam-Z, PIXL, and SuperCam, will enable unprecedented analysis of geological materials for both scientific research and determination of which samples to collect and cache for Mars sample return.

Chirality in Organic and Mineral Systems: A Review of Reactivity and Alteration Processes Relevant to Prebiotic Chemistry and Life Detection Missions

“…Additionally, organic preservation has been demonstrated to be enhanced by minerals and macromolecular matrices that provide protection against degradation; thus, organic-mineral interactions are also an area of importance when looking for potential biosignatures on other planets. There are a variety of instrument technologies that have been proposed and designed for space missions, which include a strong focus on colocated mineral and organic detection [482,483] and the separation of chiral organic molecules (e.g., [361,363,364]). The following sections describe the instruments, on three currently active missions (as of this writing), which are focused on the detection of chirality as a potential organic biosignatures.…”

Microbial Journey: Mount Everest to Mars

“…All samples will be packaged for safe transport to Earth, following planetary protection protocols, and without any contamination. These samples are also checked in real-time for the presence of organic molecules and microbial signatures using highly sophisticated instruments working on Raman and Luminescence for Organics and Chemicals (SHERLOC) [100]. However, there have been incidences when spacecraft were found to be contaminated with extremely resistant spores of Bacillus sp [101], so utmost care is taken so that these spacecraft don't contaminate the sampling expeditions.…”

A century of structural and vibrational spectroscopy in vitreous silica: A short review

“…90 SHERLOC is one of the seven scientific instrument on the Perseverance Rover that is currently operating on the Martian soil where one expects finding a significant amount of glassy materials. 91 As it is not possible to bring the samples back to earth, analyzing the spectra can only be made by comparison with existing data. This is also one reason motivating the development of databases of IR and Raman spectra of glasses.…”

“…A nice example of light, compact, and robust portable Raman and IR spectrometers are those that are part of the instrumental suites carried on missions to Mars 90 . SHERLOC is one of the seven scientific instrument on the Perseverance Rover that is currently operating on the Martian soil where one expects finding a significant amount of glassy materials 91 . As it is not possible to bring the samples back to earth, analyzing the spectra can only be made by comparison with existing data.…”