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result(s) for
"Mehall, G. L."
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The Mars 2020 Perseverance Rover Mast Camera Zoom (Mastcam-Z) Multispectral, Stereoscopic Imaging Investigation
by
Cluff, N.
,
Bailey, Z. J.
,
Barrington, M.
in
Actuation
,
Aerospace Technology and Astronautics
,
Astronomical phenomena
2021
Mastcam-Z is a multispectral, stereoscopic imaging investigation on the Mars 2020 mission’s
Perseverance
rover. Mastcam-Z consists of a pair of focusable, 4:1 zoomable cameras that provide broadband red/green/blue and narrowband 400-1000 nm color imaging with fields of view from 25.6° × 19.2° (26 mm focal length at 283 μrad/pixel) to 6.2° × 4.6° (110 mm focal length at 67.4 μrad/pixel). The cameras can resolve (≥ 5 pixels) ∼0.7 mm features at 2 m and ∼3.3 cm features at 100 m distance. Mastcam-Z shares significant heritage with the Mastcam instruments on the Mars Science Laboratory
Curiosity
rover. Each Mastcam-Z camera consists of zoom, focus, and filter wheel mechanisms and a 1648 × 1214 pixel charge-coupled device detector and electronics. The two Mastcam-Z cameras are mounted with a 24.4 cm stereo baseline and 2.3° total toe-in on a camera plate ∼2 m above the surface on the rover’s Remote Sensing Mast, which provides azimuth and elevation actuation. A separate digital electronics assembly inside the rover provides power, data processing and storage, and the interface to the rover computer. Primary and secondary Mastcam-Z calibration targets mounted on the rover top deck enable tactical reflectance calibration. Mastcam-Z multispectral, stereo, and panoramic images will be used to provide detailed morphology, topography, and geologic context along the rover’s traverse; constrain mineralogic, photometric, and physical properties of surface materials; monitor and characterize atmospheric and astronomical phenomena; and document the rover’s sample extraction and caching locations. Mastcam-Z images will also provide key engineering information to support sample selection and other rover driving and tool/instrument operations decisions.
Journal Article
The OSIRIS-REx Thermal Emission Spectrometer (OTES) Instrument
by
O’Donnell, W.
,
Bowles, H.
,
Fahlgren, J.
in
Aerospace Technology and Astronautics
,
Alanine
,
Asteroid missions
2018
The OSIRIS-REx Thermal Emission Spectrometer (OTES) will provide remote measurements of mineralogy and thermophysical properties of Bennu to map its surface, help select the OSIRIS-REx sampling site, and investigate the Yarkovsky effect. OTES is a Fourier Transform spectrometer covering the spectral range 5.71–100 μm (
1750
–
100
cm
−
1
) with a spectral sample interval of
8.66
cm
−
1
and a 6.5-mrad field of view. The OTES telescope is a 15.2-cm diameter Cassegrain telescope that feeds a flat-plate Michelson moving mirror mounted on a linear voice-coil motor assembly. A single uncooled deuterated
l
-alanine doped triglycine sulfate (DLATGS) pyroelectric detector is used to sample the interferogram every two seconds. Redundant ∼0.855 μm laser diodes are used in a metrology interferometer to provide precise moving mirror control and IR sampling at 772 Hz. The beamsplitter is a 38-mm diameter, 1-mm thick chemical vapor deposited diamond with an antireflection microstructure to minimize surface reflection. An internal calibration cone blackbody target provides radiometric calibration. The radiometric precision in a single spectrum is
≤
2.2
×
10
−
8
W
cm
−
2
sr
−
1
/
cm
−
1
between 300 and
1350
cm
−
1
. The absolute integrated radiance error is
<
1
%
for scene temperatures ranging from 150 to 380 K. The overall OTES envelope size is
37.5
×
28.9
×
52.2
cm
, and the mass is 6.27 kg. The power consumption is 10.8 W average. OTES was developed by Arizona State University with Moog Broad Reach developing the electronics. OTES was integrated, tested, and radiometrically calibrated on the Arizona State University campus in Tempe, AZ.
Journal Article
The Lucy Thermal Emission Spectrometer (L’TES) Instrument
by
Bowles, H.
,
O’Donnell, W.
,
Anwar, S.
in
Aerospace Technology and Astronautics
,
Alanine
,
Asteroid missions
2024
The Lucy Thermal Emission Spectrometer (L’TES) will provide remote measurements of the thermophysical properties of the Trojan asteroids studied by the Lucy mission. L’TES is build-to-print hardware copy of the OTES instrument flown on OSIRIS-REx. It is a Fourier Transform spectrometer covering the spectral range 5.71–100 μm (1750–100 cm
−1
) with spectral sampling intervals of 8.64, 17.3, and 34.6 cm
−1
and a 7.3-mrad field of view. The L’TES telescope is a 15.2-cm diameter Cassegrain telescope that feeds a flat-plate Michelson moving mirror mounted on a linear voice-coil motor assembly to a single uncooled deuterated
l
-alanine doped triglycine sulfate (DLATGS) pyroelectric detector. A significant firmware change from OTES is the ability to acquire interferograms of different length and spectral resolution with acquisition times of 0.5, 1, and 2 seconds. A single ∼0.851 μm laser diode is used in a metrology interferometer to provide precise moving mirror control and IR sampling at 772 Hz. The beamsplitter is a 38-mm diameter, 1-mm thick chemical vapor deposited diamond with an antireflection microstructure to minimize surface reflection. An internal calibration cone blackbody target, together with observations of space, provides radiometric calibration. The radiometric precision in a single spectrum is ≤2.2 × 10
−8
W cm
−2
sr
−1
/cm
−1
between 300 and 1350 cm
−1
. The absolute temperature error is <2 K for scene temperatures >75 K. The overall L’TES envelope size is 37.6 × 29.0 × 30.4 cm, and the mass is 6.47 kg. The power consumption is 12.6 W average. L’TES was developed by Arizona State University with AZ Space Technologies developing the electronics. L’TES was integrated, tested, and radiometrically calibrated on the Arizona State University campus in Tempe, AZ. Initial data from space have verified the instrument’s radiometric and spatial performance.
Journal Article
Mineralogy at Meridiani Planum from the Mini-TES Experiment on the Opportunity Rover
2004
The Miniature Thermal Emission Spectrometer (Mini-TES) on Opportunity investigated the mineral abundances and compositions of outcrops, rocks, and soils at Meridiani Planum. Coarse crystalline hematite and olivine-rich basaltic sands were observed as predicted from orbital TES spectroscopy. Outcrops of aqueous origin are composed of 15 to 35% by volume magnesium and calcium sulfates [a high-silica component modeled as a combination of glass, feldspar, and sheet silicates (~20 to 30%)], and hematite; only minor jarosite is identified in Mini-TES spectra. Mini-TES spectra show only a hematite signature in the millimeter-sized spherules. Basaltic materials have more plagioclase than pyroxene, contain olivine, and are similar in inferred mineral composition to basalt mapped from orbit. Bounce rock is dominated by clinopyroxene and is close in inferred mineral composition to the basaltic martian meteorites. Bright wind streak material matches global dust. Waterlain rocks covered by unaltered basaltic sands suggest a change from an aqueous environment to one dominated by physical weathering.
Journal Article
Initial Results from the Mini-TES Experiment in Gusev Crater from the Spirit Rover
2004
The Miniature Thermal Emission Spectrometer (Mini-TES) on Spirit has studied the mineralogy and thermophysical properties at Gusev crater. Undisturbed soil spectra show evidence for minor carbonates and bound water. Rocks are olivinerich basalts with varying degrees of dust and other coatings. Dark-toned soils observed on disturbed surfaces may be derived from rocks and have derived mineralogy (±5 to 10%) of 45% pyroxene (20% Ca-rich pyroxene and 25% pigeonite), 40% sodic to intermediate plagioclase, and 15% olivine (forsterite 45% ±5 to 10). Two spectrally distinct coatings are observed on rocks, a possible indicator of the interaction of water, rock, and airfall dust. Diurnal temperature data indicate particle sizes from 40 to 80 µm in hollows to ~0.5 to 3 mm in soils.
Journal Article
The Thermal Emission Imaging System (THEMIS) for the Mars 2001 Odyssey Mission
2004
The Thermal Emission Imaging System (THEMIS) on 2001 Mars Odyssey will investigate the surface mineralogy and physical properties of Mars using multi-spectral thermal-infrared images in nine wavelengths centered from 6.8 to 14.9 mm, and visible/near-infrared images in five bands centered from 0.42 to 0.86 mm. THEMIS will map the entire planet in both day and night multi-spectral infrared images at 100-m per pixel resolution, 60% of the planet in one-band visible images at 18-m per pixel, and several percent of the planet in 5-band visible color. Most geologic materials, including carbonates, silicates, sulfates, phosphates, and hydroxides have strong fundamental vibrational absorption bands in the thermal-infrared spectral region that provide diagnostic information on mineral composition. The ability to identify a wide range of minerals allows key aqueous minerals, such as carbonates and hydrothermal silica, to be placed into their proper geologic context. The specific objectives of this investigation are to: (I) determine the mineralogy and petrology of localized deposits associated with hydrothermal or sub-aqueous environments, and to identify future landing sites likely to represent these environments; (2) search for thermal anomalies associated with active sub-surface hydrothermal systems; (3) study small-scale geologic processes and landing site characteristics using morphologic and thermophysical properties; and (4) investigate polar cap processes at all seasons. THEMIS follows the Mars Global Surveyor Thermal Emission Spectrometer (TES) and Mars Orbiter Camera (MOC) experiments, providing substantially higher spatial resolution IR multi-spectral images to complement TES hyperspectral (143-band) global mapping, and regional visible imaging at scales intermediate between the Viking and MOC cameras. The THEMIS uses an uncooled microbolometer detector array for the IR focal plane. The optics consists of all-reflective, three-mirror anastigmat telescope with a 12-cm effective aperture and a speed of f/1.6. The IR and visible cameras share the optics and housing, but have independent power and data interfaces to the spacecraft. The IR focal plane has 320 cross-track pixels and 240 downtrack pixels covered by 10 --1-p.m-bandwidth strip filters in nine different wavelengths. The visible camera has a 1024 x 1024 pixel array with 5 filters. The instrument weighs 11.2 kg, is 29 cm by 37 cm by 55 cm in size, and consumes an orbital average power of 14 W.
Journal Article
The OSIRIS-REx Thermal Emission Spectrometer (OTES) Instrument
2017
The OSIRIS-REx Thermal Emission Spectrometer (OTES) will provide remote measurements of mineralogy and thermophysical properties of Bennu to map its surface, help select the OSIRIS-REx sampling site, and investigate the Yarkovsky effect. OTES is a Fourier transform spectrometer covering the spectral range 5.71 - 100 {\\mu}m (1750 - 100 cm-1) with a spectral sample interval of 8.66 cm-1 and a 6.5-mrad field of view. The OTES telescope is a 15.2-cm diameter Cassegrain telescope that feeds a flat-plate Michelson moving mirror mounted on a linear voice-coil motor assembly. A single uncooled deuterated L-alanine doped triglycine sulfate (DLATGS) pyroelectric detector is used to sample the interferogram every two seconds. Redundant ~0.855 {\\mu}m laser diodes are used in a metrology interferometer to provide precise moving mirror control and IR sampling at 772 Hz. The beamsplitter is a 38-mm diameter, 1-mm thick chemical vapor deposited diamond with an antireflection microstructure to minimize surface reflection. An internal calibration cone blackbody target provides radiometric calibration. The radiometric precision in a single spectrum is <= 2.2 x 10-8 W cm-2 sr-1/cm-1 between 300 and 1350 cm-1. The absolute integrated radiance error is <1% for scene temperatures ranging from 150 to 380 K. The overall OTES envelope size is 37.5 x 28.9 x 52.2 cm, and the mass is 6.27 kg. The power consumption is 10.8 W average. The OTES was developed by Arizona State University with Moog Broad Reach developing the electronics. OTES was integrated, tested, and radiometrically calibrated on the Arizona State University campus in Tempe, AZ.
Shape of (101955) Bennu indicative of a rubble pile with internal stiffness
2019
The shapes of asteroids reflect interplay between their interior properties and the processes responsible for their formation and evolution as they journey through the Solar System. Prior to the OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer) mission, Earth-based radar imaging gave an overview of (101955) Bennu’s shape. Here we construct a high-resolution shape model from OSIRIS-REx images. We find that Bennu’s top-like shape, considerable macroporosity and prominent surface boulders suggest that it is a rubble pile. High-standing, north–south ridges that extend from pole to pole, many long grooves and surface mass wasting indicate some low levels of internal friction and/or cohesion. Our shape model indicates that, similar to other top-shaped asteroids, Bennu formed by reaccumulation and underwent past periods of fast spin, which led to its current shape. Today, Bennu might follow a different evolutionary pathway, with an interior stiffness that permits surface cracking and mass wasting.Near-Earth asteroid Bennu has a top-like shape with longitudinal ridges, macroporosity, prominent boulders and surface mass wasting, suggesting that it is a stiff rubble pile, according to early observations by the OSIRIS-REx mission.
Journal Article