Matching Items (2)
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- All Subjects: Mass extinctions
- All Subjects: Planetary Science
- Creators: Ruff, Steven
Description
Many planetary science missions study thermophysical properties of surfaces using infrared spectrometers and infrared cameras. Thermal inertia is a frequently derived thermophysical property that quantifies the ability for heat to exchange through planetary surfaces.
To conceptualize thermal inertia, the diffusion equation analogies are extended using a general effusivity term: the square root of a product of conductivity and capacity terms. A hypothetical thermal inductance was investigated for diurnal planetary heating. The hyperbolic heat diffusion equation was solved to derive an augmented thermal inertia. The hypothetical thermal inductance was modeled with negligible effect on Mars.
Extending spectral performance of infrared cameras was desired for colder bodies in the outer solar system where peak infrared emission is at longer wavelengths. The far-infrared response of an infrared microbolometer array with a retrofitted diamond window was determined using an OSIRIS-REx—OTES interferometer. An instrument response function of the diamond interferometer-microbolometer system shows extended peak performance from 15 µm out to 20 µm and 40% performance to at least 30 µm. The results are folded into E-THEMIS for the NASA flagship mission: Europa Clipper.
Infrared camera systems are desired for the expanding smallsat community that can inherit risk and relax performance requirements. The Thermal-camera for Exploration, Science, and Imaging Spacecraft (THESIS) was developed for the Prox-1 microsat mission. THESIS, incorporating 2001 Mars Odyssey—THEMIS experience, consists of an infrared camera, a visible camera, and an instrument computer. THESIS was planned to provide images for demonstrating autonomous proximity operations between two spacecraft, verifying deployment of the Planetary Society’s LightSail-B, and conducting remote sensing of Earth. Prox-1—THESIS was selected as the finalist for the competed University Nanosatellite Program-7 and was awarded a launch on the maiden commercial SpaceX Falcon Heavy. THESIS captures 8-12 µm IR images with 100 mm optics and RGB color images with 25 mm optics. The instrument computer was capable of instrument commanding, automatic data processing, image storage, and telemetry recording. The completed THESIS has a mass of 2.04 kg, a combined volume of 3U, and uses 7W of power. THESIS was designed, fabricated, integrated, and tested in ASU’s 100K clean lab.
To conceptualize thermal inertia, the diffusion equation analogies are extended using a general effusivity term: the square root of a product of conductivity and capacity terms. A hypothetical thermal inductance was investigated for diurnal planetary heating. The hyperbolic heat diffusion equation was solved to derive an augmented thermal inertia. The hypothetical thermal inductance was modeled with negligible effect on Mars.
Extending spectral performance of infrared cameras was desired for colder bodies in the outer solar system where peak infrared emission is at longer wavelengths. The far-infrared response of an infrared microbolometer array with a retrofitted diamond window was determined using an OSIRIS-REx—OTES interferometer. An instrument response function of the diamond interferometer-microbolometer system shows extended peak performance from 15 µm out to 20 µm and 40% performance to at least 30 µm. The results are folded into E-THEMIS for the NASA flagship mission: Europa Clipper.
Infrared camera systems are desired for the expanding smallsat community that can inherit risk and relax performance requirements. The Thermal-camera for Exploration, Science, and Imaging Spacecraft (THESIS) was developed for the Prox-1 microsat mission. THESIS, incorporating 2001 Mars Odyssey—THEMIS experience, consists of an infrared camera, a visible camera, and an instrument computer. THESIS was planned to provide images for demonstrating autonomous proximity operations between two spacecraft, verifying deployment of the Planetary Society’s LightSail-B, and conducting remote sensing of Earth. Prox-1—THESIS was selected as the finalist for the competed University Nanosatellite Program-7 and was awarded a launch on the maiden commercial SpaceX Falcon Heavy. THESIS captures 8-12 µm IR images with 100 mm optics and RGB color images with 25 mm optics. The instrument computer was capable of instrument commanding, automatic data processing, image storage, and telemetry recording. The completed THESIS has a mass of 2.04 kg, a combined volume of 3U, and uses 7W of power. THESIS was designed, fabricated, integrated, and tested in ASU’s 100K clean lab.
ContributorsVeto, Michael (Author) / Christensen, Philip C (Thesis advisor) / Bell III, Jim (Committee member) / Clarke, Amanda B (Committee member) / Asphaug, Erik (Committee member) / Sariapli, Srikanth (Committee member) / Ruff, Steven (Committee member) / Arizona State University (Publisher)
Created2018
Description
There is a growing body of evidence that the evolving redox structure of the oceans has been an important influence on the evolutionary trajectory of animals. However, current understanding of connections between marine redox conditions and marine extinctions and recoveries is hampered by limited detailed knowledge of the timing, duration, and extent of marine redox changes.
The recent development of U isotopes (δ238U) in carbonates as a global ocean redox proxy has provided new insight into this problem. Reliable application and interpretation of the δ238U paleoproxy in geological records requires a thorough understanding of the reliability of δ238U recorded by bulk carbonate sediments. In this dissertation, I evaluate the robustness of δ238U paleoproxy by examining δ238U variations in marine carbonates across Permian-Triassic boundary (PTB) sections from different paleogeographic locations. Close agreement of δ238U profiles from coeval carbonate sections thousands of kilometers apart, in different ocean basins, and with different diagenetic histories, strongly suggests that bulk carbonate sediments can reliably preserve primary marine δ238U signals, validating the carbonate U-isotope proxy for global-ocean redox analysis.
To improve understanding of the role of marine redox in shaping the evolutionary trajectory of animals, high-resolution δ238U records were generated across several key evolutionary periods, including the Ediacaran-to-Early Cambrian Explosion of complex life (635-541 Ma) and the delayed Early Triassic Earth system recovery from the PTB extinction (252-246 Ma). Based on U isotope variations in the Ediacaran-to-the Early Cambrian ocean, the initial diversification of the Ediacara biota immediately postdates an episode of pervasive ocean oxygenation across the Shuram event. The subsequent decline and extinction of the Ediacara biota is coincident with an episode of extensive anoxic conditions during the latest Ediacaran Period. These findings suggest that global marine redox changes drove the rise and fall of the Ediacara biota. Based on U isotope variations, the Early Triassic ocean was characterized by multiple episodes of extensive marine anoxia. By comparing the high-resolution δ238U record with the sub-stage ammonoid extinction rate curve, it appears that multiple oscillations in marine anoxia modulated the recovery of marine ecosystems following the latest Permian mass extinction.
The recent development of U isotopes (δ238U) in carbonates as a global ocean redox proxy has provided new insight into this problem. Reliable application and interpretation of the δ238U paleoproxy in geological records requires a thorough understanding of the reliability of δ238U recorded by bulk carbonate sediments. In this dissertation, I evaluate the robustness of δ238U paleoproxy by examining δ238U variations in marine carbonates across Permian-Triassic boundary (PTB) sections from different paleogeographic locations. Close agreement of δ238U profiles from coeval carbonate sections thousands of kilometers apart, in different ocean basins, and with different diagenetic histories, strongly suggests that bulk carbonate sediments can reliably preserve primary marine δ238U signals, validating the carbonate U-isotope proxy for global-ocean redox analysis.
To improve understanding of the role of marine redox in shaping the evolutionary trajectory of animals, high-resolution δ238U records were generated across several key evolutionary periods, including the Ediacaran-to-Early Cambrian Explosion of complex life (635-541 Ma) and the delayed Early Triassic Earth system recovery from the PTB extinction (252-246 Ma). Based on U isotope variations in the Ediacaran-to-the Early Cambrian ocean, the initial diversification of the Ediacara biota immediately postdates an episode of pervasive ocean oxygenation across the Shuram event. The subsequent decline and extinction of the Ediacara biota is coincident with an episode of extensive anoxic conditions during the latest Ediacaran Period. These findings suggest that global marine redox changes drove the rise and fall of the Ediacara biota. Based on U isotope variations, the Early Triassic ocean was characterized by multiple episodes of extensive marine anoxia. By comparing the high-resolution δ238U record with the sub-stage ammonoid extinction rate curve, it appears that multiple oscillations in marine anoxia modulated the recovery of marine ecosystems following the latest Permian mass extinction.
ContributorsZhang, Feifei (Author) / Anbar, Ariel (Thesis advisor) / Gordon, Gwyneth (Committee member) / Hartnett, Hilairy (Committee member) / Wadhwa, Meenakshi (Committee member) / Ruff, Steven (Committee member) / Arizona State University (Publisher)
Created2018