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PIXL: Planetary Instrument for X-Ray Lithochemistry

A Correction to this article was published on 17 February 2021

This article has been updated


Planetary Instrument for X-ray Lithochemistry (PIXL) is a micro-focus X-ray fluorescence spectrometer mounted on the robotic arm of NASA’s Perseverance rover. PIXL will acquire high spatial resolution observations of rock and soil chemistry, rapidly analyzing the elemental chemistry of a target surface. In 10 seconds, PIXL can use its powerful 120 μm-diameter X-ray beam to analyze a single, sand-sized grain with enough sensitivity to detect major and minor rock-forming elements, as well as many trace elements. Over a period of several hours, PIXL can autonomously raster-scan an area of the rock surface and acquire a hyperspectral map comprised of several thousand individual measured points. When correlated to a visual image acquired by PIXL’s camera, these maps reveal the distribution and abundance variations of chemical elements making up the rock, tied accurately to the physical texture and structure of the rock, at a scale comparable to a 10X magnifying geological hand lens. The many thousands of spectra in these postage stamp-sized elemental maps may be analyzed individually or summed together to create a bulk rock analysis, or subsets of spectra may be summed, quantified, analyzed, and compared using PIXLISE data analysis software. This hand lens-scale view of the petrology and geochemistry of materials at the Perseverance landing site will provide a valuable link between the larger, centimeter- to meter-scale observations by Mastcam-Z, RIMFAX and Supercam, and the much smaller (micron-scale) measurements that would be made on returned samples in terrestrial laboratories.

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Change history


  1. Contamination levels are defined by IEST-STD-CC1246D, which is the successor to Mil. Std. 1246D.


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This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (80NM0018D0004). The authors gratefully acknowledge two anonymous reviewers for their helpful contributions.

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Correspondence to Abigail C. Allwood.

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The Mars 2020 Mission

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Appendix A: Parameters

Table 13 This is a complete list of parameters that are in place when a scan is initiated that are returned in data products. All of these can be changed by uplink

Appendix B: Acronyms

\(\mu \)ASC:

micro Advanced Stellar Compass


six degrees of freedom


analog front end


allowable flight temperature


Alpha Proton X-ray Spectrometer


body unit electronics


Contamination Control


camera detectors SLI mount


command reply frame


digital-to-analog converter


digital elevation model


direct from Earth


detector signal processing chain


Technical University of Denmark


element-specific calibration factor


engineering model


engineering uplink/downlink lead


flood light illuminators


flood light illuminator electronics


fundamental parameter


full width at half maximum


gas Dust Removal Tool


Hall-effect sensor


heat microbial reduction


high-output paraffin


high-voltage multiplier module


high-voltage power supply


instrument flight software


instrument science data system


Jet Propulsion Laboratory


low-voltage control module


micro context camera


micro context camera electronics


Mars Science Laboratory


modulation transfer function




non-volatile residue


optical fiducial subsystem


Planetary Data Systems


product generation executable


Planetary Instrument for X-ray Lithochemistry


Planetary Protection


packaging qualification and verification




rover avionics mounting panel


random sample consensus


region of interest


root sum square


sample caching system


silicon-drift detectors


Science Data Frame


structured light illuminators


structured light illuminator electronics


spherically mounted retroreflectors


small movement scans


Space Physics Research Laboratory


science uplink/downlink lead


thermoelectric cooler




terrain relative translation


United States Geological Survey


worst cold case


worst hot case


X-ray fluorescence


X-ray source assembly

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Allwood, A.C., Wade, L.A., Foote, M.C. et al. PIXL: Planetary Instrument for X-Ray Lithochemistry. Space Sci Rev 216, 134 (2020).

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