| 1. |
- Bradak, Balazs, et al.
(författare)
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Searching for potential multi-hazard events during the last 1.5 million years of the Pleistocene epoch
- 2022
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Ingår i: Forum Geografi. - : Muhammadiyah University Press. - 0852-0682 .- 2460-3945. ; 36:1, s. 39-53
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Tidskriftsartikel (refereegranskat)abstract
- Increasing attention has been paid to multi-hazards in environmental disaster studies produced during thelast decade. Multi-hazard studies focus on the occurrence, interaction and effect of several natural hazardsin the same region. Despite the increasing number of multi-hazard studies, few investigations have focusedon global-scale multi-hazard events. With the aim of closing this gap, our study focuses on the identificationof periods during the last 1.5 million years of the Pleistocene epoch, with the quasi-parallel appearance ofnatural hazards (e.g., asteroid impacts and large volcanic eruptions with a Volcanic Explosivity Index (VEI)of 8 and 7) amplifying their individual effects and thus causing long-term, global-scale changes. Of the sevenidentified potential multi-hazard events, three were considered as possible global-scale events with a longerterm environmental (paleoclimatic) impact; dated to c.a., 1.4 Ma (marine isotope stage – MIS45), 1.0 Ma(MIS 27), and 100 ka (MIS 5c), respectively. Two additional periods (around 50 and 20 ka) were identifiedas being associated with more restricted scale multi-hazard events, which might cause a “Little Ice Age-like”climatic episode in the history of the Pleistocene Period. In addition, we present a hypothesis about thecomplex climatic response to a global-scale multi-hazard event consisting of a series of asteroid impacts andvolcanic eruption linked to a geomagnetic polarity change, namely the Matuyama-Brunhes Boundary, whichmight be accompanied by global cooling and result in the final step of the Early Middle Pleistocene Transition.
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| 2. |
- Dunér, David, et al.
(författare)
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Astrobiology and Society in Europe
- 2018
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Ingår i: Astrobiology and Society in Europe Today. - Cham : Springer International Publishing. - 9783319962641 ; , s. 7-10
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Bokkapitel (refereegranskat)
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| 3. |
- Jones, Geraint H., et al.
(författare)
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The Comet Interceptor Mission
- 2024
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Ingår i: Space Science Reviews. - : Springer Nature. - 0038-6308 .- 1572-9672. ; 220:1
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Tidskriftsartikel (refereegranskat)abstract
- Here we describe the novel, multi-point Comet Interceptor mission. It is dedicated to the exploration of a little-processed long-period comet, possibly entering the inner Solar System for the first time, or to encounter an interstellar object originating at another star. The objectives of the mission are to address the following questions: What are the surface composition, shape, morphology, and structure of the target object? What is the composition of the gas and dust in the coma, its connection to the nucleus, and the nature of its interaction with the solar wind? The mission was proposed to the European Space Agency in 2018, and formally adopted by the agency in June 2022, for launch in 2029 together with the Ariel mission. Comet Interceptor will take advantage of the opportunity presented by ESA’s F-Class call for fast, flexible, low-cost missions to which it was proposed. The call required a launch to a halo orbit around the Sun-Earth L2 point. The mission can take advantage of this placement to wait for the discovery of a suitable comet reachable with its minimum Δ V capability of 600 ms − 1 . Comet Interceptor will be unique in encountering and studying, at a nominal closest approach distance of 1000 km, a comet that represents a near-pristine sample of material from the formation of the Solar System. It will also add a capability that no previous cometary mission has had, which is to deploy two sub-probes – B1, provided by the Japanese space agency, JAXA, and B2 – that will follow different trajectories through the coma. While the main probe passes at a nominal 1000 km distance, probes B1 and B2 will follow different chords through the coma at distances of 850 km and 400 km, respectively. The result will be unique, simultaneous, spatially resolved information of the 3-dimensional properties of the target comet and its interaction with the space environment. We present the mission’s science background leading to these objectives, as well as an overview of the scientific instruments, mission design, and schedule.
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| 4. |
- Konatham, Samuel, 1992-
(författare)
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Atmospheric Species and Spectral Radiation in Terrestrial Exoplanets : Implications for Astrobiology
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The physical properties of the planets and their parent stars are fundamental in the composition of atmospheres and radiative environments, which fundamentally determine their surface temperature and habitability. The atmospheric composition and radiation play a vital role in the emergence of life. This doctoral thesis presents two main results: 1. A method that uses the physical properties of the planets and their parent stars to infer the potential atmospheric compositions of the known exoplanets. For that, fundamental physics concepts and the basics of the kinetic theory of gases are used. Additionally, a new list of potentially habitable exoplanets is presented based on the resulting atmospheric compositions and the criteria that Earth-like atmospheres that can host liquid water should be considered habitable. The presented method also provides a preliminary classification of exoplanets similar to Earth (in terms of atmosphere) and their potential habitability. 2. A study of the impact of the radiation environment on the development and evolution of the human visual system towards optimal use of the available radiation. Human vision's possible evolutionary directions are presented while overcoming the shortcomings in the existing studies. The human visual system is hypothesised to have evolved in conjugation with the prevailing spectral radiation environment for photopic (daytime) and scotopic (night-time). One of the main novelties of this study is the comparison of the human vision bandwidth with the Full Width at half-maximum (FWHM) of the radiation reaching the shallow depths of the ocean, which may suggest that this is optimized for the development of animal sight during the formation of the early proto-visual system. Moreover, the observed maximum absorption wavelength during photopic vision (555nm) correlates with the maximum total energy for a 300 nm vision bandwidth. Furthermore, the analysis of the radiation environment at different solar zenith angles (SZA) during dusk suggests that the scotopic vision evolved to optimize information retrieval during these hours. The work presented in this thesis contributes to perform screening of Earth-like exoplanets and the study of astrobiological or space exploration aspects such as potential habitability, human-like vision, photosynthesis efficiency and evolution of life systems on exoplanets.
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| 5. |
- Orgel, Csilla, et al.
(författare)
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Gridmapping the Northern Plains of Mars: A New Overview of Recent Water‐ and Ice‐Related Landforms in Acidalia Planitia.
- 2019
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Ingår i: Journal of Geophysical Research - Planets. - 2169-9100. ; 124:2, s. 454-82
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Tidskriftsartikel (refereegranskat)abstract
- We used a grid‐mapping technique to analyze the distribution of 13 water‐ and ice‐related landforms in Acidalia Planitia as part of a joint effort to study the three main basins in the northern lowlands of Mars, that is, Acidalia, Utopia, and Arcadia Planitiae. The landforms were mapped at full Context Camera resolution along a 300‐km‐wide strip from 20°N to 84°N. We identified four landform assemblages: (1) Geologically recent polar cap (massive ice), which superposes the latitude‐dependent mantle (LDM) (LA1); (2) ice‐related landforms, such as LDM, textured terrain, small‐scale polygons, scalloped terrain, large‐scale viscous flow features, and gullies, which have an overlapping distribution (LA2); (3) surface features possibly related to water and subsurface sediment mobilization (LA3; kilometer‐scale polygons, large pitted mounds, small pitted mounds, thumbprint terrain); and (4) irregularly shaped pits with raised rims on equator‐facing slopes. Pits are likely the result of an energetic release of volatiles (H2O, CO2, and CH4), rather than impact‐, volcanism‐, or wind‐related processes. LDM occurs ubiquitously from 44°N to 78°N in Acidalia Planitia. Various observations suggest an origin of air fall deposition of LDM, which contains less ice in the uppermost tens of meters in Acidalia Planitia than in Arcadia and Utopia Planitiae. However, LDM may be thicker and more extended in the past in Acidalia Planitia. The transition between LDM‐free terrain and LDM is situated further north than in Utopia and Arcadia Planitiae, suggesting different past and/or present climatic conditions among the main basins in the northern lowlands.
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| 6. |
- Ramsdale, Jason D., et al.
(författare)
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Gridmapping the northern plains of Mars: Geomorphological, Radar and Water-Equivalent Hydrogen results from Arcadia Plantia.
- 2019
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Ingår i: Journal of Geophysical Research - Planets. - 2169-9100. ; 124:2, s. 504-27
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Tidskriftsartikel (refereegranskat)abstract
- A project of mapping ice‐related landforms was undertaken to understand the role of subsurface ice in the northern plains. This work is the first continuous regional mapping from CTX (ConTeXt Camera, 6 m/pixel; Malin et al., 2007) imagery in Arcadia Planitia along a strip 300 km across stretching from 30°N to 80°N centered on the 170°W line of longitude. The distribution and morphotypes of these landforms were used to understand the permafrost cryolithology. The mantled and textured signatures occur almost ubiquitously between 35°N and 78°N and have a positive spatial correlation with inferred ice stability based on thermal modeling, neutron spectroscopy, and radar data. The degradational features into the LDM (latitude‐dependent mantle) include pits, scallops, and 100‐m polygons and provide supporting evidence for subsurface ice and volatile loss between 35 and 70°N in Arcadia with the mantle between 70 and 78°N appearing much more intact. Pitted terrain appears to be much more pervasive in Arcadia than in Acidalia and Utopia suggesting that the Arcadia study area had more widespread near‐surface subsurface ice and thus was more susceptible to pitting or that the ice was less well buried by sediments. Correlations with ice stability models suggest that lack of pits north of 65–70°N could indicate a relatively young age (~1 Ma); however, this could also be explained through regional variations in degradation rates. The deposition of the LDM is consistent with an air fall hypothesis; however, there appears to be substantial evidence for fluvial processes in southern Arcadia with older, underlying processes being equally dominant with the LDM and degradation thereof in shaping the landscape.
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| 7. |
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| 8. |
- Vakkada Ramachandran, Abhilash
(författare)
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A planetary chamber to investigate the thermal and water cycle on Mars
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The water processes that affect the upper layers of the surface of Mars are not yet fully understood. Describing the processes that may induce changes in the water content ofthe surface is critical to determine the present-day habitability of the Martian surface,understand the atmospheric water cycle, and estimate the efficiency of future water extraction procedures from the regolith for In-Situ-Resource-Utilization (ISRU). This PhD thesis describes the design, development, and plausible uses of a Martian environmental facility ‘SpaceQ chamber’ which allows to simulate the near surface water cycle.This facility has been specifically designed to investigate the effect of water on the Martian surface. SpaceQ has been used to investigate the material curation and has demonstrated that the regolith, when mixed with super absorbent polymer (SAP), water, and binders exposed to Martian conditions, can form a solid block, and retain more than 80% of the added water, which may be of interest to screen radiation while maintaining a low weight. The thesis also includes the testing of HABIT operation, of theESA/IKI ExoMars 2022 robotic mission to Mars, within the SpaceQ chamber, underMartian conditions similar to those expected at Oxia Planum. The tests monitor the performance of the brine compartment, when deliquescent salts are exposed to atmospheric water.In this thesis, a computational model of the SpaceQ using COMSOL Multiphysics has been implemented to study the thermal gradients and the near surface water cycle under Martian temperature and pressure experimental conditions. The model shows good agreement with experiments on the thermal equilibration time scales and gradients. The model is used to extrapolate the one-point relative humidity measurement of the experimental to each grid points in the simulation. This gives an understanding ofthe gradient in atmospheric water relative humidity to which the experimental samples such as deliquescent salts and Martian regolith simulants are exposed at different time intervals. The comparison of the thermal simulation and the experimental behavior of HABIT instrument tests, shows an extra internal heating source of about 1 W which can be attributed to the hydration and deliquescence of the salts exposed to Martian conditions when in contact with atmospheric moisture.Finally, this thesis experimentally demonstrates that pure liquid water can persist for 3.5 to 4.5 hours at Mars surface conditions. The simulated ground captured 53% of the atmospheric water either as pure liquid water, hydrate, or brine. The result concludes that the relative humidity values at night-time on Mars may allow for significant water absorption by the ground, which is released at sunrise. The water cycle dynamics near the surface is therefore always out of equilibrium. After frost formation, thin films of water may survive for a few hours. The results of this thesis about the water cycle on Mars, and about the interaction of atmospheric water with regolith and salts, have implications for the present-day habitability of the Martian surface and planetary protection policies.
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