| 1. |
- Escamilla-Roa, Elizabeth, et al.
(författare)
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DFT study of the reduction reaction of calcium perchlorate on olivine surface : Implications to formation of Martian’s regolith
- 2020
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Ingår i: Applied Surface Science. - : Elsevier. - 0169-4332 .- 1873-5584. ; 512
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Tidskriftsartikel (refereegranskat)abstract
- Perchlorates have been found widespread on the surface of Mars, their origin and degradation pathways are not understood to date yet. We investigate here, from a theoretical point of view, the potential redox processes that take place in the interaction of Martian minerals such as olivine, with anhydrous and hydrated perchlorates. For this theoretical study, we take as mineral substrate the (1 0 0) surface of forsterite and calcium perchlorate salt as adsorbate. Our DFT calculations suggests a reduction pathway to chlorate and chlorite. When the perchlorate has more than 4 water molecules, this mechanism, which does not require high-temperature or high energy sources, results in parallel with the oxidation of the mineral surface, forming magnesium peroxide, MgO2, and in the formation of ClO3, which through photolysis is known to form ClO-O2. Because of the high UV irradiance that reaches the surface of Mars, this may be a source of O2 on Mars. Our results suggest that this process may be a natural removal pathway for perchlorates from the Martian regolith, which in the presence of atmospheric water for salt hydration, can furthermore lead to the production of oxygen. This mechanism may thus have implications on the present and future habitability of the Martian surface.
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| 2. |
- Galvez-Martinez, Santos, et al.
(författare)
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Ar+ ion bombardment dictates glycine adsorption on pyrite (100) surface : X-ray photoemission spectroscopy and DFT approach
- 2020
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Ingår i: Applied Surface Science. - : Elsevier. - 0169-4332 .- 1873-5584. ; 530
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Tidskriftsartikel (refereegranskat)abstract
- Ar+ ion sputtering on pyrite surfaces leads to the generation of sulfur vacancies and metallic iron. Our research shows that sputtering and annealing processes drive electrostatic changes on the pyrite surface, which play an important role in the molecular adsorption of glycine. While both chemical species (anion and zwitterion) adsorb on a sputtered pyrite surface, the anionic form of glycine is favoured. Nevertheless, in both treatments (sputtered or annealed surfaces), molecules evolve from zwitterionic to anionic species over time. Quantum mechanical calculations based in Density Functional Theory (DFT) suggest the energy required to generate vacancies increases with the number of vacancies produced, and the atomic charge of the Fe atoms that is next to a vacancy increases linearly with the number of vacancies. This leads to enhanced redox processes on the sputtered pyrite surface that favour the adsorption of glycine, which is confirmed experimentally by X-ray Photoemission Spectroscopy (XPS). We have investigated theoretically the efficiency of the adsorption process of the zwitterionic glycine onto vacancies sites: this reaction is exothermic, i.e. is energetically favoured and its energy increases with the number of defects, confirming the increased reactivity observed experimentally. The experiments show a treatment-dependent molecular selectivity of the pyrite surface.
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| 3. |
- Mathanlal, Thasshwin
(författare)
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Development of robotic instruments and techniques for space and astrobiological exploration and research
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Astrobiology is the study of life in the universe. The search for life beyond the Earth requires an understanding of the signatures of life, and of the nature of the environments that support it. Space exploration is a crucial factor to achieve these goals. The PhD thesis focusses on developing novel techniques for astrobiological and Earth exploration. It includes instrument prototyping, validation and calibration of a flight-ready space in-strument.This thesis explains the development of four instruments namely 1) KORE – a robotic exploration rover designed for subsurface analogue planetary explorations; 2) InXSpace3D – a 3D mapping payload for biogeomorphological analysis based on a com-mercial RGB-D camera and an open-source algorithm; 3) S3ME2 – a self-sustainable environmental monitoring station capable of withstanding harsh environments on Earth; and 4) PACKMAN – a space weather monitoring instrument. The instruments are devoted to: 1) the spatial exploration and characterization (KORE and InXSpace3D) of a potentially habitable environment and 2) the monitorization of the rapidly vary-ing environmental variables that may affect life (S3ME2 and PACKMAN), its evolution and preservation. The instruments are developed according to the Technology Readiness Level (TRL) Ladder and a cost and time effective methodology which maximizes the use of Commercial Off-The-Shelf (COTS) components and Open source software.The thesis also discusses the bioburden sterilization and control procedure of some of the sensors on the flight-ready space Instrument HABIT (HabitAbility: Brines, Irradi-ation and Temperature), that will be part of the ExoMars 2022 mission. Again, a COTS and an open source software-based approach has been used in these higher TRL level procedures. This demonstrates the fact that such an engineering approach can benefit the scientific community by developing instruments with a minimal investment of time and resources without compromising the scientific quality of the instrument. The thesis concludes with the adaptation of the research methodology to adapt space technologies that are applicable in space for human support systems to address an emerging problem on Earth: ATMO-Vent, a low-cost COTS-based ventilator that produces an adapted breathable atmosphere for COVID-19 patients.During the PhD thesis, the author has published five peer-reviewed journal papers, two peer-reviewed conference abstracts and two co-authored peer-reviewed journal pa-pers. The first authored papers and conference abstracts have been appended to the Part-II of the thesis.
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| 4. |
- Nazarious, Miracle Israel, 1992-
(författare)
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Scientific Instruments to Facilitate the Human Exploration of Mars
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This PhD thesis describes, from an engineering perspective, some of the preliminary steps that need to be implemented to facilitate the human exploration of Mars. It focuses on the development of a set of novel scientific or technology demonstrator instruments. The engineering problem starts with a conceptual idea and the definition of individual functional requirements, that may be related to scientific or technological objectives. To solve this problem, an unique approach adapted during this thesis, allowed for designing and building efficiently, testing and refining the instruments in multiple iterations using simple techniques like 3-D printing, breadboard prototyping and low-cost commercial off the shelf (COTS) components. This approach reduces the cost and facilitates the accessibility of space instrument design and testing to a broader community. The steps include demonstrating the operability of the concept with prototypes, calibrating the responses and validating their operation in representative environments, thereby raising the technology readiness level (TRL) of the instrument with a lower investment in time and resources than traditional approaches that use specialized components and fabrica-tion techniques.The thesis provides a detailed description of the design and development process, and discusses the calibration and validation results of four different instruments, namely: 1) Brine Observation Transition To Liquid Experiment (BOTTLE) as a part of HabitAbil-ity: Brines, Irradiation and Temperature (HABIT) instrument onboard the ESA/IKI’s ExoMars 2022 Surface Platform Kazachok, for investigating the surface environmen-tal conditions and demonstrating the capability of salts to absorb water on Mars, 2) Metabolt, a small-sized portable incubator to monitor the behaviour of the microbiome in soils, which will be a critical element of future greenhouses on Mars or the Moon, 3) Methanox, an in-situ resource utilization demonstrator for converting local resources on Mars and producing methane and ammonia as space fuel, and 4) PRessure Optimized PowEred Respirator (PROPER), a wearable cleanroom developed for protecting the hu-mans against biological pathogens, showing the direct applicability of this research to solve Earth-based problems. During the final phase of the PhD thesis, the world suffered the COVID-19 pandemic. This challenge provided an opportunity to test the approach presented in this thesis and inspired the development of this equipment, and may also be of relevance to protect from biological cross-contamination in planetary habitats and laboratories while handling local regolith materials and samples on Mars.This work also highlights the calibration of the HABIT Flight Model (FM) in the cleanroom of Omnisys Instruments AB, Sweden, defines the retrieval models that will be used during ExoMars 2022 mission operations and data archiving in the Planetary Science Archive (PSA). Parts of this thesis were already published in the form of peer-reviewed journal articles and conference abstracts.
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| 5. |
- Sam, Lydia, et al.
(författare)
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Small Lava Caves as Possible Exploratory Targets on Mars : Analogies Drawn from UAV Imaging of an Icelandic Lava Field
- 2020
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Ingår i: Remote Sensing. - : MDPI. - 2072-4292. ; 12:12
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Tidskriftsartikel (refereegranskat)abstract
- Volcanic-aeolian interactions and processes have played a vital role in landscape evolution on Mars. Martian lava fields and associated caves have extensive geomorphological, astrobiological, and in-situ resource utilization (ISRU) implications for future Mars missions which might be focused on subsurface exploration. Although several possible cave “skylights” of tens to >100 m diameter have been spotted in lava fields of Mars, there is a possibility of prevalence of meter-scale features which are an order of magnitude smaller and difficult to identify but could have vital significance from the scientific and future exploration perspectives. The Icelandic volcanic-aeolian environment and fissure volcanoes can serve as analogs to study lava flow-related small caves such as surface tubes, inflationary caves, liftup caves, and conduits. In the present work, we have tried to explore the usability of unmanned aerial vehicle (UAV)-derived images for characterizing a solidified lava flow and designing a sequential methodology to identify small caves in the lava flow. In the mapped area of ~0.33 km2, we were able to identify 81 small cave openings, five lava flow morphologies, and five small cave types using 2 cm/pixel high-resolution images. The results display the usefulness of UAV imaging for such analogous research, and also highlight the possibility of the widespread presence of similar small cave openings in Martian lava fields. Such small openings can facilitate optimal air circulation within the caves while sheltering the insides from physical weathering and harmful radiations. Using the available best resolution remote sensing images, we extend the analogy through the contextual and geomorphological analysis of several possible pit craters in the Tharsis region of Mars, in a region of extremely vesicular and fragile lava crust with pahoehoe-type morphology. We report two possible pit craters in this region, with diameters as small as ~20 m. The possibility that such small cave openings can lead to vast subterranean hollow spaces on Mars cannot be ruled out considering its low gravity.
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| 6. |
- Soria-Salinas, Álvaro
(författare)
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Development of the Wind and Air Temperature Sensor of the ExoMars 2022 HABIT Instrument
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This work presents the development, validation and calibration of the air temperature sensors (ATS) and the air and wind retrieval method of the HABIT (HabitAbility: Brines, Irradiation and Temperature) instrument. HABIT is one of the two European payloads of the ESA/Roscosmos ExoMars 2022 mission that will land at Oxia Planum (18.20° N, 335.45° E), on Mars.One of the main novelties of this Ph.D. thesis is to use the thin fins that work as ATS on HABIT as a wind sensor for the planetary boundary layer of Mars. The thesis is based on the study and modelling of heat transfer along three rods when exposed to forced convection in a gaseous fluid, and that is tested: (1) through computational fluid dynamic simulations, which provided inputs to the early design of the HABIT structure; (2) under laboratory conditions, with the use of a specifically designed prototype and a cooling fan; and (3) within a subsonic wind tunnel facility under terrestrial conditions.A preliminary validation of the wind speed retrieval approach is first performed using temperature measurements from Mars provided by the Rover Environmental Monitoring Station (REMS) instrument, on board the NASA Curiosity rover of the Mars Science Laboratory (MSL) mission. The method is based on modelling forced convection of the ATS of REMS when assumed as thin rods immersed in the extreme low-pressure and high-radiating atmospheric conditions of the Martian thermal boundary layer, at a height of ∼ 1.5 m from the surface. Assuming the previously reported REMS wind sensor (WS) retrieval errors of 20% for the wind speed, ±30° for the horizontal “front” wind directions, and ±45° for the horizontal “rear” wind directions, agreement with the WS values of up to 77% of the acquisition time, on average, for wind speeds and coincidence between 60% and 80% of the time for wind directions is reported for some sols. These promising results are limited to only evening extended acquisitions from 18:00 to 21:00 local mean solar time (LMST) and orientations within the validity region of the retrieval. That is, the method was only considered valid over a narrow angle range of 13° to 107° in azimuth angle. In addition to this, the results of this first study suggested a new optimal orientation when using the ATS for wind speed and direction retrievals of +60° clockwise with respect to the forward direction of the Curiosity rover.The wind retrieval model is also validated and calibrated with the HABIT engineering and qualification model (EQM) in the Aarhus Wind Tunnel Simulator (AWTS) of the Aarhus University, Denmark. The AWTS is designed to reproduce typical winds on the surface of Mars. The data acquired during the wind tunnel campaign were used to validate the forced convective and radiative heat transfer model for each of the three ATS. The campaign investigated winds in steady CO2 flows at a pressure of 9.9 mbar, an ambient temperature of 25°C, and for horizontal free-stream velocities between 0.8 and 12 m/s. Several relationships between the Nusselt number and the Reynolds and Prandtl numbers reported in the literature were evaluated in the tunnel to model forced convection through the ATS rods. Where needed, corrections to account for radiative heat transfer within the AWTS were implemented to correct for experimental artefacts. The tests demonstrated that this retrieval method can be used to derive wind speed for frontal winds on Mars in the range of 0 to 10 m/s, with an error of ±0.3 m/s, using the cooling profile of the ATS rod 3, and for lateral winds in the range of 0 to 6 m/s, with an error of ±0.3 m/s, using the ATS rod 2 cooling profile.The thesis also includes the calibration of the HABIT ATS flight model (FM) in the clean room of Omnisys Instruments AB, and the retrieval model that will be used in operations during the ExoMars 2022 mission and for archiving in the Planetary Science Archive (PSA) of the European Space Agency (ESA).Finally, the wind retrieval method developed in this thesis can be applied not only to the future analysis of HABIT data at Oxia Planum, but also to re-analyse the ATS data of REMS at Gale crater, and for future comparative analysis with the HABIT/ExoMars 2022, the Temperature and Wind Sensors for InSight (TWINS)/InSight, and the Mars Environmental Dynamics Analyzer (MEDA)/Mars 2020 rover instruments.
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