Scheld et al MIA LSA5

MIA: Miniature In-Situ Rock Analysis Requiring Minimal Preparation

P.E. Clark1, W. Farrand2, Joseph P Martin3, John R Marshall4, Larry W Mason5, Dan Scheld3 1. IACS/CUA, 2. Space Science Institute, 3. N-Science Corp, 4. SETI Institute, 5. Lockheed

Martin

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Scheld et al MIA LSA5

MIA Next Generation In Situ XRF/XRD

rapid, quantitative in-situ contextual analysis of unexplored surfaces and/or potential samples prior to collection

minimized instrument complexity, mass, volume, and power usage.

No sample handling, eliminating source of contamination

XRF and XRD proven techniques for planetary geochemical studies (e.g., Clark et al., 1976, Science, 194, 1283-88)

chemical analysis and mineralogical identification AS WELL AS a petrological framework based on mapping the form, size, and relationships between crystalline minerals (Inter- and intra-grain texture).

Current in-situ XRD devices (Blake et al, 2005, LPS 35, 1608) depend on extensive sample preparation requiring many moving parts and increased operational complexity, mass, cost, power, and volume.

MICA (Marshall et al., 2006, MTP EICR-9/06-MICA) and CMIST (Clark et al., 2010, LEAG, 3008) have demonstrated clearly that costly and risky sample processing equipment required by CheMin is not necessary for meaningful diffraction information.

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X-ray lines: An X-ray source sends a collimated beam toward a sample.

These X-rays either diffract from the sample at angles characteristic of mineral structure or cause element-characteristic emission of X-ray energies.

A photon-counting, energy-resolving X-ray CCD captures some of these X-rays and produces an event list, which can be transformed into both fluorescence and diffraction information on a photon by photon basis.

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n λ = 2 d sin (θ)

Scheld et al MIA LSA5

In the XRD/XRF and imaging geometry illustrated, the grazing incident X-rays are scattered and detected by the X-ray CCD at 2 angles from 22° to 62° and energy identified from 1.6 to 9 Kev.

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Original Concept: The original prototype for MICA was packaged as two components, a sensor head at the point of sample contact, and a power and control assembly, to allow flexibility for placement on a rover.

The electronic circuit components required for control and operation of the X-ray source, X-ray CCD, CCD temperature control, light source, the microscopic imager, and a fine position control are all packaged in the Sensor Head. All the software for control, operation and data acquisition and processing is contained in Labview based software in the MIA computer supplemented by a field programmable gate array (FPGA) in the sensor head.

The sensor head configuration had a cylindrical lower section containing the X-ray source, X-ray CCD, thermal control elements, illuminator LEDs for imaging, and a mechanism for aperture opening. For thermal control, the outer surface is divided into two thermally decoupled radiators. 4/14/15

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MIA New Approach for even greater capability:

state-of-the-art compact X-ray tubes;

photon-counting, spectroscopic, imaging X-ray CCDs for simultaneous energy-dispersive XRF and angle-dispersive XRD;

compact Raman spectrometer to confirm XRD mineral identifications and identify additional minerals and volatiles and an optical micro-imager to enhance textural analysis.

layout and sample interface designed to sample the same spot

prototype, test, and integrate state of the art, compact components;

test performance of the instrument with standard mineral assemblages of known composition analogous to Mars, the Moon, similar to samples used to provide qualitative assessment of CMIST.

systematic sampling methodology will include development and testing of a standardized interface and orientation technique for considering a sample from a range of orientations, consideration of sample faces with or without polishing.

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Some Proof of Concept Tests:

aluminum calibration plate to verify characteristic diffraction and elemental abundance lines

quartzite rock. Diffraction patterns associated with each sample are clearly seen.

Proof of concept for the MICA XRF prototype took measurements of a rock sample before and after desert varnish was removed, clearly indicating the siderophile element enhancement in desert varnish.

Lunar Analog (gabbroic anorthosite )rock to verify characteristic diffraction and elemental abundance lines.

Standard mineral assemblages representing rock suite analogs for lunar rocks clearly indicated the presence of elements and diffraction lines associated with major elements, as well as crystalline texture of the rock.

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Scheld et al MIA LSA5

Al2O3 calibration analysis with MICA prototype shows excellent correlation between MICA measured diffraction pattern and JCPDS standard.

Al2O3 XRD arcs showing locus of full energy (8.05 keV Cu K-alpha) collected by binning of full energy x-rays.

Diffraction results from MICA Prototype with Alumina plate

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Quartzite XRD pattern. The histogram angular positions are shown with the JCPDS standard pattern for quartz. The JCPDS angles but not the amplitudes are well represented by the XRD pattern, as expected for larger grain sizes.

Quartzite XRD spot map on CCD. The intense spots correspond to the few larger crystallites in the rock that happen to have crystal planes oriented at the appropriate Bragg angles.

XRD Diffraction from quartz rock by MICA Prototype

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Unprepared known sample of anorthositic gabbro of small to moderate grain size showing CMIST capability to distinguish and characterize phases for anticipated minerals. Color coded d-spacings (left) distinguish major minerals by miller index. Map of crystal orientations (right) shows Laue spots of the mineral grains, including the morphology of an olivine crystal (circled).

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Strategic Knowledge Gaps Relationship

Moon: identify regolith resources including pyroclastics, hydrates and likely volatile-bearing minerals (e.g., apatite), Al-, Ti-, Fe-rich deposits

Mars: identify regolith resources, geochemical evidence for water or biogenicity, sedimentary minerals indicative of climate variations/hydrological cycles, igneous minerals indicative of volcanism

Asteroids: identify regolith resources including hydrates, organics, nature and distribution of FeNi and Mg/Fe silicate assemblages, variations in composition associated with rock fragments and dust as well as geographic location

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Future Plans:

We have taken the first steps to develop and demonstrate a powerful reconnaissance tool for planetary lander/rover operations that simulates a field geologist with capabilities similar to those of her/his home laboratory. MICA was designed specifically for Mars but is adaptable to any planetary surface.

A compact version of this instrument could be carried on the end of a rover arm to nondestructively assess the mineralogical and elemental state and the petrology of any rock sample placed directly in its field of view.

Our next steps involve developing the next-generation low mass (<5 kg), compact (coffee can size) Miniature In-situ Analyzer (MIA), using state-of-the-art hardware, including compact X-ray tubes; photon-counting, spectroscopic, imaging X-ray CCDs for simultaneous energy-dispersive XRF and angle-dispersive XRD; and a COTS compact spectrometer.

Our goal will be high sensitivity (major and minor elements from C to Ni) and high resolution (<150 eV FWHM) spectrometry, as well as a broader context for interpretation through addition of a near IR or Raman spectral imaging. We will develop a repeatable sampling methodology, utilizing a standard sampling interface usable from a robotic arm. We will validate MIA's performance using standard mineral assemblages representing analogues of rock types on Mars, the Moon, and asteroids.

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what science investigations, orbital or surface, do we need to perform to answer the unanswered questions and what our challenges and solutions to performing these? In situ determination sample origin and history without sample handling

holes in our scientific knowledge of the lunar surface? Rock suites implied via remote sensing but not collected directly

what are the science investigations we should be performing next? In situ analysis along geological traverses of features with widely varying illumination, thermal, particle and volatile exposure conditions (e.g., permanently shadowed craters)

Nature of investigations: MIA measurements of exposed rocks at outcrops along traverses with rover

Technical, program challenges: proposed incorporation state of the art components for next generation, adequate support for instrument development programs