<p>VERITAS is a proposed Discovery mission concept, currently in Step 2 (Ph... more <p>VERITAS is a proposed Discovery mission concept, currently in Step 2 (Phase A), and would launch in 2026. VERITAS addresses one of the most fundamental questions in rocky planetary evolution: why did twin planets follow different evolutionary paths? Venus’ hot lithosphere may be a good analog for early Earth, and could be responsible for the apparent lack of plate tectonics.  Determining the factors that lead to the initiation of plate tectonics would inform our predictions for rocky Earth-sized exoplanets.  VERITAS answers key questions about Venus’ geologic evolution and searches for current activity and evidence for past or present water.</p> <p><strong>Payload:</strong> VERITAS carries two instruments and conducts gravity science. The VISAR X-band [Hensley et al., this meeting] measurements include: 1) a global digital elevation model (DEM) with 250 m postings, 5 m height accuracy, 2) Synthetic aperture radar (SAR) imaging at 30 m horizontal resolution globally, 3) SAR imaging at 15 m resolution > 20% of the surface and 4) surface deformation from RPI at 2 mm precision for at least 12 targeted, potentially active areas. VEM [Helbert et al., this meeting] would produce surface coverage of most of the surface in 6 NIR bands located within 5 atmospheric windows and of 8 atmospheric bands for calibration and water vapor measurements. VERITAS would use Ka-band uplink and downlink to create a global gravity field with 3 mgal accuracy / 160 km resolution.</p> <p><strong>Science:</strong> VERITAS looks for the chemical fingerprint of past water in the form of low Fe, high Si rock in the tessera plateaus [Dyar et al. submitted, 2020; Helbert et al., submitted, 2020] and for present day volcanic outgassing of volatiles in the form of near surface water outgassing due to recent or active volcanism. </p> <p>VERITAS uses a variety of approaches to search for present day activity, including 1) tectonic and volcanic cm-scale surface deformation, 2) chemical weathering, 3) thermal emission from recent or active volcanism, 4) topographic or surface roughness changes, and 5) comparisons to past mission data sets.</p> <p>VERITAS constrains rocky planet evolution via: 1) examining the origin of tesserae plateaus -possible continent-like features, 2) assessing the history of volcanism, 3) looking for evidence of prior tectonic or impact features buried by volcanism, and 4) determining the origin of tectonic features such as huge arcuate troughs that have been compared to Earth’s subduction zones.</p> <p>VERITAS gravity data (resolution 160 km, 3x better than avg. Magellan resolution), would enable estimation of elastic thickness (a proxy for thermal gradient) and determination of core size [Mazerico et al. Fall AGU 2019].</p> <p> </p> <p><strong>Conclusions</strong>: VERITAS would create a rich data set of high-resolution topography, imaging, spectroscopy, and gravity. These co-registered data would be on par with those acquired for Mercury, Mars and the Moon that have revolutionized our understanding of these bodies. In addition to answering fundamental science questions, VERITAS’ data would motivate further Venus missions.  Active surface deformation would promote a seismic mission. Accurate topography plus surface rock type would optimize targeting of surface or areal missions.</p> <p><em>Acknowledgements</em>: A portion of this research was conducted at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. The information presented to about the VERITAS mission concept is pre-decisional and is provided for planning and discussion purposes only.</p>
<p><strong>Introduction:</strong> The Venus Emissivity ... more <p><strong>Introduction:</strong> The Venus Emissivity Mapper is the first flight instrument designed to focus on mapping the surface of Venus using several atmospheric windows around 1 µm. After years of development, VEM now has a mature design. An existing laboratory prototype has verified an achievable instrument SNR of well above 1000, as well as predicted error in retrieval of relative emissivity of better than 1%, assuming the availability of improved Venus topography.</p><p><strong>VEM science goals: </strong>The instrument will provide a global map of rock type from orbit, assessing iron contents and the redox state of the surface by observing the surface with six narrow band filters, ranging from 0.86 to 1.18 µm. Three additional windows allow corrections for cloud composition and variability, two measure water abundance, and three compensate for stray light. Continuous observation of Venus’ thermal emission will also place tighter constraints on current volcanic activity. Eight channels provide measurements of atmospheric water vapor abundance as well as cloud microphysics and dynamics, permitting accurate correction of atmospheric interference on the surface data.</p><p>The instrument is currently part of two Phase A studies: is part of the payload of the NASA VERITAS mission as well as of the ESA EnVision mission, here as the VenSpec-M channel in the VenSpec spectrometer suite. </p><p>Combining VEM with a high-resolution radar mapper will provide key insights into the divergent evolution of Venus and Earth. Flying VEM on more than one mission will enable a long timeline of monitoring for volcanic activity on Venus. Combined with the existing VenusExpress data, VEM enables detection and mapping of surface changes over decades.</p><p><strong>VEM Design:</strong> The VEM system design is a pushbroom multispectral imaging system. It leverages a proven measurement technique pioneered by VIRTIS on Venus Express (VEX). It also incorporates lessons learned from VIRTIS to achieve greatly improved sensitivity and spectral and spatial coverage:</p><ul><li>A filter array (rather than a grating) provides wavelength stability (band-center and width-scatter) ~5× more stable and maximizes signal to the focal-plane array (FPA).</li> <li>Spectral windows below 1µm are covered for the first time.</li> <li>A two-stage baffle decreases scattered light and improves sensitivity.</li> <li>Use of an InGaAs detector with an integrated thermal electric cooler (TEC) eliminates the need for cryogenic cooling.</li> </ul><p>The design maturity, combined with a standard camera optical design, leads to low development risk.</p><p><strong>VEM prototyping:</strong> VEM has been under development for several years with significantly financial investment from DLR. Following creation of the first breadboard model in 2015 during Phase A for the NASA Discovery proposal VERITAS, a laboratory prototype (LP) of the VEM instrument has been developed. This prototype includes the development version of the VEM optics with a filter array with two active filter strips. The optics underwent a set of calibration measurements on sub-unit level at LATMOS prior to delivery to DLR. All key optical design parameters including transmission and wavelength coverage have been verified using the VEMO prototype.</p><p><strong>A first performance evaluation</strong> of the VEM prototype used two Venus analog samples heated to Venus surface temperatures. This was performed using the Venus simulations setup at the Planetary Spectroscopy Laboratory with the prototype mounted on the chamber. The retrieved emissivities match laboratory values, and uncertainty for a single unbinned exposure is <0.35%. VEM uses onboard software developed for MERTIS to bin, co-add, and losslessly compress data upon uplink command. During science orbits, VEM oversamples at 10 km spatial resolution (33×33 pixel binning). To further enhance SNR, VEM uses digitial TDI to provide 189× gain over single-pixel SNR. Based upon current performance of the laboratory prototype for a single unbinned exposure and SNR enhancement due to onboard processing, we expect a system SNR of well beyond 1000.</p><p><strong>VEM atmospheric correction</strong>: Methodology for retrieving surface emissivity is complex but well understood and demonstrated. To distinguish between surface and atmospheric contributions, VEM uses an updated version of the extensively tested pipeline developed to process VIRTIS data, combined with a radiative transfer model (RTM). Surface emissivity retrieval techniques were developed based on Galileo NIMS observations at 1700, 1800 and 2300 nm. VEM cloud bands occur at 1195,…
Obtaining quantitative chemical information using laser-induced breakdown spectroscopy is challen... more Obtaining quantitative chemical information using laser-induced breakdown spectroscopy is challenging due to the variability in the bulk composition of geological materials. Chemical matrix effects caused by this variability produce changes in the peak area that are not proportional to the changes in minor element concentration. Therefore the use of univariate calibrations to predict trace element concentrations in geological samples is plagued by a high degree of uncertainty. This work evaluated the accuracy of univariate minor element predictions as a function of the composition of the major element matrices of the samples and examined the factors that limit the prediction accuracy of univariate calibrations. Five different sample matrices were doped with 10–85 000 ppm Cr, Mn, Ni, Zn, and Co and then independently measured in 175 mixtures by X-ray fluorescence, inductively coupled plasma atomic emission spectrometry, and laser-induced breakdown spectroscopy, the latter at three di...
... Fe 3+ and Fe 2+ partitioning among silicates in metapelites: A synchrotron micro-XANES study.... more ... Fe 3+ and Fe 2+ partitioning among silicates in metapelites: A synchrotron micro-XANES study. M. Darby Dyar 1 ,* , Emily W. Lowe 1 , Charles V. Guidotti 2 and Jeremy S. Delaney 3 1 Department ... al. 1996, 1998; Dyar et al. 2001). With ...
... No dejaba de sorprender el hecho de que la Mineralogical Society of America, la sociedad mine... more ... No dejaba de sorprender el hecho de que la Mineralogical Society of America, la sociedad mineralógica más importan-te e influyente del mundo, editora, entre otros, de la prestigiosa revista American Mineralogist y los excelentes monográficos Reviews in Mineralogy and ...
<p>VERITAS is a proposed Discovery mission concept, currently in Step 2 (Ph... more <p>VERITAS is a proposed Discovery mission concept, currently in Step 2 (Phase A), and would launch in 2026. VERITAS addresses one of the most fundamental questions in rocky planetary evolution: why did twin planets follow different evolutionary paths? Venus’ hot lithosphere may be a good analog for early Earth, and could be responsible for the apparent lack of plate tectonics.  Determining the factors that lead to the initiation of plate tectonics would inform our predictions for rocky Earth-sized exoplanets.  VERITAS answers key questions about Venus’ geologic evolution and searches for current activity and evidence for past or present water.</p> <p><strong>Payload:</strong> VERITAS carries two instruments and conducts gravity science. The VISAR X-band [Hensley et al., this meeting] measurements include: 1) a global digital elevation model (DEM) with 250 m postings, 5 m height accuracy, 2) Synthetic aperture radar (SAR) imaging at 30 m horizontal resolution globally, 3) SAR imaging at 15 m resolution > 20% of the surface and 4) surface deformation from RPI at 2 mm precision for at least 12 targeted, potentially active areas. VEM [Helbert et al., this meeting] would produce surface coverage of most of the surface in 6 NIR bands located within 5 atmospheric windows and of 8 atmospheric bands for calibration and water vapor measurements. VERITAS would use Ka-band uplink and downlink to create a global gravity field with 3 mgal accuracy / 160 km resolution.</p> <p><strong>Science:</strong> VERITAS looks for the chemical fingerprint of past water in the form of low Fe, high Si rock in the tessera plateaus [Dyar et al. submitted, 2020; Helbert et al., submitted, 2020] and for present day volcanic outgassing of volatiles in the form of near surface water outgassing due to recent or active volcanism. </p> <p>VERITAS uses a variety of approaches to search for present day activity, including 1) tectonic and volcanic cm-scale surface deformation, 2) chemical weathering, 3) thermal emission from recent or active volcanism, 4) topographic or surface roughness changes, and 5) comparisons to past mission data sets.</p> <p>VERITAS constrains rocky planet evolution via: 1) examining the origin of tesserae plateaus -possible continent-like features, 2) assessing the history of volcanism, 3) looking for evidence of prior tectonic or impact features buried by volcanism, and 4) determining the origin of tectonic features such as huge arcuate troughs that have been compared to Earth’s subduction zones.</p> <p>VERITAS gravity data (resolution 160 km, 3x better than avg. Magellan resolution), would enable estimation of elastic thickness (a proxy for thermal gradient) and determination of core size [Mazerico et al. Fall AGU 2019].</p> <p> </p> <p><strong>Conclusions</strong>: VERITAS would create a rich data set of high-resolution topography, imaging, spectroscopy, and gravity. These co-registered data would be on par with those acquired for Mercury, Mars and the Moon that have revolutionized our understanding of these bodies. In addition to answering fundamental science questions, VERITAS’ data would motivate further Venus missions.  Active surface deformation would promote a seismic mission. Accurate topography plus surface rock type would optimize targeting of surface or areal missions.</p> <p><em>Acknowledgements</em>: A portion of this research was conducted at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. The information presented to about the VERITAS mission concept is pre-decisional and is provided for planning and discussion purposes only.</p>
<p><strong>Introduction:</strong> The Venus Emissivity ... more <p><strong>Introduction:</strong> The Venus Emissivity Mapper is the first flight instrument designed to focus on mapping the surface of Venus using several atmospheric windows around 1 µm. After years of development, VEM now has a mature design. An existing laboratory prototype has verified an achievable instrument SNR of well above 1000, as well as predicted error in retrieval of relative emissivity of better than 1%, assuming the availability of improved Venus topography.</p><p><strong>VEM science goals: </strong>The instrument will provide a global map of rock type from orbit, assessing iron contents and the redox state of the surface by observing the surface with six narrow band filters, ranging from 0.86 to 1.18 µm. Three additional windows allow corrections for cloud composition and variability, two measure water abundance, and three compensate for stray light. Continuous observation of Venus’ thermal emission will also place tighter constraints on current volcanic activity. Eight channels provide measurements of atmospheric water vapor abundance as well as cloud microphysics and dynamics, permitting accurate correction of atmospheric interference on the surface data.</p><p>The instrument is currently part of two Phase A studies: is part of the payload of the NASA VERITAS mission as well as of the ESA EnVision mission, here as the VenSpec-M channel in the VenSpec spectrometer suite. </p><p>Combining VEM with a high-resolution radar mapper will provide key insights into the divergent evolution of Venus and Earth. Flying VEM on more than one mission will enable a long timeline of monitoring for volcanic activity on Venus. Combined with the existing VenusExpress data, VEM enables detection and mapping of surface changes over decades.</p><p><strong>VEM Design:</strong> The VEM system design is a pushbroom multispectral imaging system. It leverages a proven measurement technique pioneered by VIRTIS on Venus Express (VEX). It also incorporates lessons learned from VIRTIS to achieve greatly improved sensitivity and spectral and spatial coverage:</p><ul><li>A filter array (rather than a grating) provides wavelength stability (band-center and width-scatter) ~5× more stable and maximizes signal to the focal-plane array (FPA).</li> <li>Spectral windows below 1µm are covered for the first time.</li> <li>A two-stage baffle decreases scattered light and improves sensitivity.</li> <li>Use of an InGaAs detector with an integrated thermal electric cooler (TEC) eliminates the need for cryogenic cooling.</li> </ul><p>The design maturity, combined with a standard camera optical design, leads to low development risk.</p><p><strong>VEM prototyping:</strong> VEM has been under development for several years with significantly financial investment from DLR. Following creation of the first breadboard model in 2015 during Phase A for the NASA Discovery proposal VERITAS, a laboratory prototype (LP) of the VEM instrument has been developed. This prototype includes the development version of the VEM optics with a filter array with two active filter strips. The optics underwent a set of calibration measurements on sub-unit level at LATMOS prior to delivery to DLR. All key optical design parameters including transmission and wavelength coverage have been verified using the VEMO prototype.</p><p><strong>A first performance evaluation</strong> of the VEM prototype used two Venus analog samples heated to Venus surface temperatures. This was performed using the Venus simulations setup at the Planetary Spectroscopy Laboratory with the prototype mounted on the chamber. The retrieved emissivities match laboratory values, and uncertainty for a single unbinned exposure is <0.35%. VEM uses onboard software developed for MERTIS to bin, co-add, and losslessly compress data upon uplink command. During science orbits, VEM oversamples at 10 km spatial resolution (33×33 pixel binning). To further enhance SNR, VEM uses digitial TDI to provide 189× gain over single-pixel SNR. Based upon current performance of the laboratory prototype for a single unbinned exposure and SNR enhancement due to onboard processing, we expect a system SNR of well beyond 1000.</p><p><strong>VEM atmospheric correction</strong>: Methodology for retrieving surface emissivity is complex but well understood and demonstrated. To distinguish between surface and atmospheric contributions, VEM uses an updated version of the extensively tested pipeline developed to process VIRTIS data, combined with a radiative transfer model (RTM). Surface emissivity retrieval techniques were developed based on Galileo NIMS observations at 1700, 1800 and 2300 nm. VEM cloud bands occur at 1195,…
Obtaining quantitative chemical information using laser-induced breakdown spectroscopy is challen... more Obtaining quantitative chemical information using laser-induced breakdown spectroscopy is challenging due to the variability in the bulk composition of geological materials. Chemical matrix effects caused by this variability produce changes in the peak area that are not proportional to the changes in minor element concentration. Therefore the use of univariate calibrations to predict trace element concentrations in geological samples is plagued by a high degree of uncertainty. This work evaluated the accuracy of univariate minor element predictions as a function of the composition of the major element matrices of the samples and examined the factors that limit the prediction accuracy of univariate calibrations. Five different sample matrices were doped with 10–85 000 ppm Cr, Mn, Ni, Zn, and Co and then independently measured in 175 mixtures by X-ray fluorescence, inductively coupled plasma atomic emission spectrometry, and laser-induced breakdown spectroscopy, the latter at three di...
... Fe 3+ and Fe 2+ partitioning among silicates in metapelites: A synchrotron micro-XANES study.... more ... Fe 3+ and Fe 2+ partitioning among silicates in metapelites: A synchrotron micro-XANES study. M. Darby Dyar 1 ,* , Emily W. Lowe 1 , Charles V. Guidotti 2 and Jeremy S. Delaney 3 1 Department ... al. 1996, 1998; Dyar et al. 2001). With ...
... No dejaba de sorprender el hecho de que la Mineralogical Society of America, la sociedad mine... more ... No dejaba de sorprender el hecho de que la Mineralogical Society of America, la sociedad mineralógica más importan-te e influyente del mundo, editora, entre otros, de la prestigiosa revista American Mineralogist y los excelentes monográficos Reviews in Mineralogy and ...
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