The Mineralogical, Elemental, and Tomographic Reconnaissance Investigation for CLPS (METRIC) is an instrument suite comprising an X-ray Diffraction/X-ray Fluorescence instrument (XRD, mineral structure analysis; XRF, elemental composition analysis) and an X-ray micro Computed Tomography instrument (XCT, 3D internal micromorphological analysis) mounted on a CLPS lander, with an imaging infrared spectrometer (IRS, mineralogy and spatial geological context) onboard a small supplemental rover. 

The 2022 proposed mission (NASA ROSES PRISM) will use this suite to quantify the mineralogy, composition, and micromorphology of the regolith and rocks at the Birkeland crater landing site to address key questions about the early evolution of the Moon. Over the course of a lunar day, the mission will use a Honeybee Robotics (HBR) SPEAR drill on the lander to collect regolith for measurement with the XRD/F and XCT, and a rover traverse to image the regolith and boulders within the surrounding area will be conducted with the IRS .

Figure 1: Proposed landing sites at Birkeland crater on the lunar farside.
Figure 2: System layout on a nonspecific CLPS lander

eXaminart Instrument Suite


The XRD/F will provide definitive and quantitative mineralogy and geochemistry, enabling the most diagnostic and complete characterization of regolith possible with landed spacecraft.

The XRD/F instrument (Fig. 3) draws on heritage from the Mars Science Laboratory CheMin instrument[3] and improves upon the design in multiple ways[4]. Like CheMin, Rietveld refinement and fullpattern fitting of METRIC XRD data can identify minerals at a detection limit of ~1 wt.%, quantify their abundances when present at >3 wt.%, and determine elemental composition of all minerals present at >5 wt.% from their refined lattice parameters[5,6].

The angular range of the METRIC XRD has been shifted to higher 2θ compared to CheMin to enable detection of elemental iron, making it more relevant for use on the Moon. The most significant improvement to the CheMin design is the production of two X-ray beams to analyze materials for XRD and XRF separately, allowing for quantitative geochemical analysis.

Figure 3. XRD/F instrument design, using a split beam geometry to maximize XRD and XRF data separately.

XCT is a non-destructive, high resolution three-dimensional imaging technique used to analyze the internal features of multiphase materials and to characterize porous granular materials[7,8]. The XCT instrument will, for the first time, determine the 3D internal micromorphology of a lunar soil sample in situ on the lunar surface. This will serve as a ground-breaking technology demonstration of XCT on another planetary surface.

The METRIC XCT design (Fig. 4) utilizes components already developed to high TRL for XRD/F and implemented in PIXI, reducing the cost and schedule risk normally associated with development of a new instrument. Data collected by the breadboard version of METRIC XCT have a 30 µm spatial resolution, allowing for the characterization of grain sizes and shapes as well as vesicle shape, size, and orientation[9]. Crystal morphologies derived from METRIC XCT data complement the bulk mineralogy determined by METRIC XRD and provide a measure of grain size distribution for the different phases.

Figure 4. XCT instrument design, which incorporates XRD/F components.

3D reconstruction of a lunar regolith analog sample. Credit: R. Hanna, N. Vo.


  • NASA Johnson Space Center
  • Colorado School of Mines
  • SETI Institute
  • JPL
  • Univ. Hawaii
  • Northern Arizona Univ.
  • Honeybee Robotics
  • Texas A&M Univ.
  • Baja Technologies
  • Univ. Arizona
  • Rutgers Univ.

  • Univ. Texas at Austin
  • Univ. Michigan
  • Goddard Space Flight Center
  • University of Maryland
  • UNLV
  • PSI
  • Jacobs at NASA JSC
  • CNRS – Universite Paul Cezanne
  • European Synchrotron Radiation Facility
  • Diamond Light Source


  • [1] Rampe E. B. et al. (2022) Abstract # 2093. LPSC 2022
  • [2] Zacny K. et al. (2014) IEEE. 
  • [3] Blake D. F. et al. (2012) Space Sci. Rev., 170, 341- 478. 
  • [4] Blake D. F. et al. (2022) Abstract # 1612. LPSC 2022. 
  • [5] Morrison S. M. et al. (2018) Am. Min., 10.2138/am2018-6123. 
  • [6] Rampe E. B. et al. (2020) Geochem., 80, 125605 
  • [7] Falvard S. & Paris R. (2017) Sedimentol., 64, 453-477. 
  • [8] Thakur M. M. & Penumadu D. (2020) Comp. Geotech., 124, 103638 
  • [9] Obbard R. W. et al. (2022) Abstract # 2314. LPSC 2022