| 1. |
- Coustenis, A., et al.
(författare)
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TandEM : Titan and Enceladus mission
- 2009
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Ingår i: Experimental astronomy. - : Springer Science and Business Media LLC. - 0922-6435 .- 1572-9508. ; 23:3, s. 893-946
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Tidskriftsartikel (refereegranskat)abstract
- TandEM was proposed as an L-class (large) mission in response to ESA's Cosmic Vision 2015-2025 Call, and accepted for further studies, with the goal of exploring Titan and Enceladus. The mission concept is to perform in situ investigations of two worlds tied together by location and properties, whose remarkable natures have been partly revealed by the ongoing Cassini-Huygens mission. These bodies still hold mysteries requiring a complete exploration using a variety of vehicles and instruments. TandEM is an ambitious mission because its targets are two of the most exciting and challenging bodies in the Solar System. It is designed to build on but exceed the scientific and technological accomplishments of the Cassini-Huygens mission, exploring Titan and Enceladus in ways that are not currently possible (full close-up and in situ coverage over long periods of time). In the current mission architecture, TandEM proposes to deliver two medium-sized spacecraft to the Saturnian system. One spacecraft would be an orbiter with a large host of instruments which would perform several Enceladus flybys and deliver penetrators to its surface before going into a dedicated orbit around Titan alone, while the other spacecraft would carry the Titan in situ investigation components, i.e. a hot-air balloon (MontgolfiSre) and possibly several landing probes to be delivered through the atmosphere.
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| 2. |
- Sakatani, N., et al.
(författare)
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Anomalously porous boulders on (162173) Ryugu as primordial materials from its parent body
- 2021
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Ingår i: Nature Astronomy. - : Springer Nature. - 2397-3366. ; 5:8, s. 766-774
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Tidskriftsartikel (refereegranskat)abstract
- Planetesimals—the initial stage of the planetary formation process—are considered to be initially very porous aggregates of dusts1,2, and subsequent thermal and compaction processes reduce their porosity3. The Hayabusa2 spacecraft found that boulders on the surface of asteroid (162173) Ryugu have an average porosity of 30–50% (refs. 4,5,6), higher than meteorites but lower than cometary nuclei7, which are considered to be remnants of the original planetesimals8. Here, using high-resolution thermal and optical imaging of Ryugu’s surface, we discovered, on the floor of fresh small craters (<20 m in diameter), boulders with reflectance (~0.015) lower than the Ryugu average6 and porosity >70%, which is as high as in cometary bodies. The artificial crater formed by Hayabusa2’s impact experiment9 is similar to these craters in size but does not have such high-porosity boulders. Thus, we argue that the observed high porosity is intrinsic and not created by subsequent impact comminution and/or cracking. We propose that these boulders are the least processed material on Ryugu and represent remnants of porous planetesimals that did not undergo a high degree of heating and compaction3. Our multi-instrumental analysis suggests that fragments of the highly porous boulders are mixed within the surface regolith globally, implying that they might be captured within collected samples by touch-down operations10,11.
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| 3. |
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| 4. |
- Wada, K., et al.
(författare)
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Asteroid Ryugu before the Hayabusa2 encounter
- 2018
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Ingår i: Progress in Earth and Planetary Science. - : Springer Science and Business Media LLC. - 2197-4284. ; 5:1
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Tidskriftsartikel (refereegranskat)
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| 5. |
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| 6. |
- Mueller, N., et al.
(författare)
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Near Surface Properties of Martian Regolith Derived From InSight HP3-RAD Temperature Observations During Phobos Transits
- 2021
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Ingår i: Geophysical Research Letters. - : John Wiley & Sons. - 0094-8276 .- 1944-8007. ; 48:15
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Tidskriftsartikel (refereegranskat)abstract
- We use the Martian surface temperature response to Phobos transits observed next to the InSight lander in Elysium Planitia to constrain the thermal properties of the uppermost layer of regolith. Modeled transit lightcurves validated by solar panel current measurements are used to modify the boundary conditions of a 1D heat conduction model. We test several model parameter sets, varying the thickness and thermal conductivity of the top layer to explore the range of parameters that match the observed temperature response within its uncertainty both during the eclipse as well as the full diurnal cycle. The measurements indicate a thermal inertia (TI) of in the uppermost layer of 0.2–4 mm, significantly smaller than the TI of derived from the diurnal temperature curve. This could be explained by larger particles, higher density, or some or slightly higher amount of cementation in the lower layers.
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| 7. |
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| 8. |
- Oberst, J., et al.
(författare)
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Planetary polar explorer – the case for a next-generation remote sensing mission to low Mars orbit
- 2022
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Ingår i: Experimental Astronomy. - : Springer Science and Business Media LLC. - 0922-6435 .- 1572-9508. ; 54, s. 695-711
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Tidskriftsartikel (refereegranskat)abstract
- We propose the exploration of polar areas on Mars by a next-generation orbiter mission. In particular, we aim at studying the seasonal and regional variations in snow-deposits, which – in combination with measurements of temporal variations in rotation and gravity field – will improve models of the global planetary CO2 cycle. A monitoring of polar scarps for rock falls and avalanche events may provide insights into the dynamics of ice sheets. The mapping of the complex layering of polar deposits, believed to contain an important record of climate history, may help us understand the early climate collapse on the planet. Hence, we propose an innovative next-generation exploration mission in polar circular Low Mars Orbit, which will be of interest to scientists and challenging to engineers alike. Schemes will be developed to overcome atmosphere drag forces acting upon the spacecraft by an electric propulsion system. Based on the experience of missions of similar type in Earth orbit we believe that a two-year mission in circular orbit is possible at altitudes as low as 150 km. Such a mission opens new opportunities for novel remote sensing approaches, not requiring excessive telescope equipment or power. We anticipate precision altimetry, powerful radars, high-resolution imaging, and magnetic field mapping. © 2022, The Author(s).
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