Perseverance’s Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) Investigation
Authors: Bhartia Rohit , Beegle Luther W. , DeFlores Lauren , Abbey William , Razzell Hollis Joseph , Uckert Kyle , Monacelli Brian , Edgett Kenneth S. , Kennedy Megan R. , Sylvia Margarite , Aldrich David , Anderson Mark , Asher Sanford A. , Bailey Zachary , Boyd Kerry , Burton Aaron S. , Caffrey Michael , Calaway Michael J. , Calvet Robert , Cameron Bruce , Caplinger Michael A. , Carrier Brandi L. , Chen Nataly , Chen Amy , Clark Matthew J. , Clegg Samuel , Conrad Pamela G. , Cooper Moogega , Davis Kristine N. , Ehlmann Bethany , Facto Linda , Fries Marc D. , Garrison Dan H. , Gasway Denine , Ghaemi F. Tony , Graff Trevor G. , Hand Kevin P. , Harris Cathleen , Hein Jeffrey D. , Heinz Nicholas , Herzog Harrison , Hochberg Eric , Houck Andrew , Hug William F. , Jensen Elsa H. , Kah Linda C. , Kennedy John , Krylo Robert , Lam Johnathan , Lindeman Mark , McGlown Justin , Michel John , Miller Ed , Mills Zachary , Minitti Michelle E. , Mok Fai , Moore James , Nealson Kenneth H. , Nelson Anthony , Newell Raymond , Nixon Brian E. , Nordman Daniel A. , Nuding Danielle , Orellana Sonny , Pauken Michael , Peterson Glen , Pollock Randy , Quinn Heather , Quinto Claire , Ravine Michael A. , Reid Ray D. , Riendeau Joe , Ross Amy J. , Sackos Joshua , Schaffner Jacob A. , Schwochert Mark , O Shelton Molly , Simon Rufus , Smith Caroline L. , Sobron Pablo , Steadman Kimberly , Steele Andrew , Thiessen Dave , Tran Vinh D. , Tsai Tony , Tuite Michael , Tung Eric , Wehbe Rami , Weinberg Rachel , Weiner Ryan H. , Wiens Roger C. , Williford Kenneth , Wollonciej Chris , Wu Yen-Hung , Yingst R. Aileen , Zan Jason 
Published: May 2021

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.