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Until recently, the influence of basal liquid water on the evolution of buried glaciers in Mars' mid latitudes was assumed to be negligible because the latter stages of Mars' Amazonian period (3 Ga to present) have long been thought to have been similarly cold and dry to today. Recent identifications of several landforms interpreted as eskers associated with these young (100s Ma) glaciers calls this assumption into doubt. They indicate basal melting (at least locally and transiently) of their parent glaciers. Although rare, they demonstrate a more complex mid-to-late Amazonian environment than was previously understood. Here, we discuss several open questions posed by the existence of glacier-linked eskers on Mars, including on their global-scale abundance and distribution, the drivers and dynamics of melting and drainage, and the fate of meltwater upon reaching the ice margin. Such questions provide rich opportunities for collaboration between the Mars and Earth cryosphere research communities. Funder: French Space Agency CNES; STFC (ST/V50693X/1); NASA (80NSSC21K0908); UK Space Agency (ST/R001405/1, ST/T002913/1, ST/V005332/1, ST/W002744/1, ST/W002949/1)

The material strength of meteorites provides useful information on the make-up and history of asteroids. However, the unique determination of the material strength of a meteorite is difficult because of the wide range of strengths many meteorites exhibit. Even within a single sample, complicated textures and mineral granular compositions make measurements difficult. Michikami et al. (2019) investigated the impact-induced crack growth in ordinary (L5) chondrites and indicated that crack growth is largely affected by the strength of individual mineral grains (and/or chondrules). In this study, we examine the strengths of mineral grains in carbonaceous meteorites qualitatively. To this end, we use X-ray microtomography to investigate how chondrules are affected by impact-induced crack growth in carbonaceous meteorites. Spherical alumina projectiles with a diameter of 1.0 mm were fired into the surfaces of seven Allende (CV) meteorite target samples with sizes of -1 to 2 cm at a nominal impact velocity of 2.0 km/s. In addition, spherical glass projectiles with a diameter 0.8 mm were fired into the target surfaces of two Murchison (CM) and two Aguas Zarcas (CM) meteorite target samples with sizes of -2 cm at a nominal impact velocity of 4.0 km/s. The results show that most cracks in CV chondrites tend to grow along the boundary surfaces of the chondrules, while most chondrule-related cracks in CM samples grow regardless of the boundary surfaces of the chondrules. This suggests that crack growth is largely affected by the chondrules' strength as indicated by Michikami et al. (2019). The weaker the strength of chondrules, the more likely crack growth tends to occur regardless of chondrule boundaries. We found that the mesostasis of chondrules in CM meteorite Murchison (and likely Aguas Zarcas) has experienced aqueous alteration and the chondrules have become structurally weak as a whole. This indicates that impact-induced crack propagation in CM chondrites differs from thermal-fatigue induced crack propagation inferred from previous studies. As the sample material to be returned from asteroid Bennu is considered to be related to CM chondrites, we propose that observation of the cracks in chondrules in Bennu samples might tell us whether those cracks are impact- or thermal-fatigue-induced. Validerad;2023;Nivå 2;2023-01-16 (sofila);Funder: JSPS KAKENHI (grant nos. JP20K04048 and JP20H00205); Chinese Academy of Sciences International Fellowship for Visiting Scientists (grant no. 2019VCA0004); SNSA (Dnr. 2021-00078); Hypervelocity Impact Facility, ISAS, JAXA

In this abstract we discuss a proposal for a microgravity flight campaign within which we will investigate penetrometry in a microgravity environment. Understanding the mechanical properties of solar system minor bodies is essential for understanding their origin and evolution. Past missions such as Hayabusa-2 and OSIRIS-REX have landed on asteroids and taken samples to discover what these bodies are made of. However, there has been conflicting evidence and reports into the physical properties of the granular surface material of these bodies. With future missions such as JAXA’s MMX mission travelling to Phobos to take a sample of the body the results from this campaign will be very important to that and future missions. Penetrometry, i.e. the determination of the reaction force an object experiences as it penetrates into a surface, can help to understand the essential properties regarding regolith such as grain size, grain shape, cohesion and bulk density. The usage of penetrometry however has mostly been limited ground-based studies such as soil sciences or even cheese maturation. Very little is known about the underlying physics of penetrometry. Results of penetrometry experiments are largely analysed based on empirical models, which presents us with a challenge if we want to apply the same parameters to understand granular materials on asteroid surfaces. Obviously, gravity cannot be eliminated in the laboratory. Hence, it is essential to verify penetrometry as a method and validate penetrometry instrument designs in microgravity.For this purpose, we propose a parabolic flight campaign. Our experiment will test the use of penetrometry in asteroid-analogue environments by investigating samples with varying properties such as grain size and shape. The microgravity aspect of the experiment is one of the most important factors because it enables us to correlate laboratory experiments at 1g with identical setups in a gravity regime relevant to asteroids. The proposed experimental setup will include a variety of samples with varying grain sizes, grain shapes, porosities and grain size distributions. The penetrometer used will also have varying properties such as the diameter, shape, and velocity of penetration. A robotic arm will push a penetrometer into the samples to measure the reaction force which can then be used to determine the mechanical properties of the samples. By varying the samples and penetrometer properties it will be possible to better understand the relevant parameters affecting reaction force. The suitability of the setup will also be reviewed to understand its usage and applicability in microgravity environments such as the robotic arm that will be used. All of the experiments carried out during the parabolic campaign will also be done at 1g to compare the tests in varying gravity levels. With a better understanding of the science behind penetrometry and the effects of microgravity, future missions will be better prepared and be able to use penetrometry more effectively to understand small-body surfaces.

We use the surface temperature response to Phobos transits as observed by a radiometer on board of the InSight lander to constrain the thermal properties of the uppermost layer of regolith. Modeled...

We explore the origins of a complex assemblage of sinuous ridges in Chukhung crater (38.47°N, 72.42°W), Tempe Terra, Mars, and discuss the implications of the landsystem for post-Noachian fluvial and glaciofluvial activity in this location [1].We produced a geomorphic map of Chukhung crater using a basemap of 6 m/pixel Context Camera (CTX) images and a 75 m/pixel High Resolution Stereo Camera digital elevation model (DEM). We used 25 cm/pixel High Resolution Imaging Science Experiment images, and a 24 cm/pixel DEM generated from CTX stereopair images [2] to aid classifications of sinuous ridges into four morpho-stratigraphic subtypes. We constrained an age envelope of ~2.1–3.6 Ga for Chukhung crater using modelled ages (from crater size-frequency analyses) of units above and below it in the regional stratigraphy. We derived a minimum model age of ~330 Ma for viscous flow features (putative debris-covered glaciers) in southern Chukhung crater.Sinuous ridges in southern Chukhung crater emerge from moraine-like deposits associated with the debris-covered glaciers. Sinuous ridges in northern Chukhung crater extend from dendritic fluvial valley networks on the crater wall. The northern sinuous ridges are most likely to be inverted palaeochannels, which comprise subaerial river sediments exhumed as ridges by erosion of surrounding materials.Both sinuous ridge subtypes in southern Chukhung crater have numerous esker-like properties. Eskers are ridges of glaciofluvial sediment deposited in meltwater tunnels within or beneath glacial ice. One of the ridge subtypes in southern Chukhung crater is best explained as eskers because these ridges ascend the sides of their host valleys and, in places, escape over them onto adjacent plains. Post-depositional processes can cause inverted paleochannels to cross local undulations in the contemporary topography [3] but the ascent and escape over larger, pre-existing topographic divides is (as yet) not adequately explained by these mechanisms. Eskers, in contrast, form under hydraulic pressure in ice-confined tunnels, and commonly ascend valley walls and cross topographic divides. The esker-like properties of the second sinuous ridge subtype in southern Chukhung crater can also be explained under the inverted palaeochannel hypothesis so the origins of these ridges remain more ambiguous.Chukhung crater has undergone protracted and/or episodic modification by liquid water since its formation between the early Hesperian and early Amazonian. This falls after the Noachian period (>3.7 Ga), when most major fluvial activity on Mars occurred. Esker-forming wet-based glaciation in Chukhung crater might have occurred as recently as the mid Amazonian (>330 Ma), when climate conditions are thought to have been cold and hyper-arid. Rare occurrences of eskers associated with Amazonian-aged glaciers in Mars’ mid-latitudes are attributed to transient, localised geothermal heating within tectonic rift/graben settings [4]. The location of Chukhung crater between major branches of the large Tempe Fossae volcano-tectonic rift system is consistent with this hypothesis.References: [1] Butcher et al. 2021, Icarus 357, 114131. [2] Mayer and Kite 2016, Lunar Planet. Sci. Conf. Abstract #1241. [3] Lefort et al. 2012, J. Geophys. Res. Planets 117, E03007. [4] Butcher et al. 2017, J. Geophys. Res. Planets 122, 2445–2468.

International audience; We present a geomorphic map of Chukhung crater (38.47°N, 72.42°W) in central Tempe Terra, Mars. Chukhung crater formed ~3.6–2.1 Ga, between the early Hesperian and early Amazonian periods of Mars' geologic history. It hosts dendritic networks of crater wall valleys, broad crater floor valleys, mid-to-late-Amazonian-aged debris-covered glaciers, moraine-like deposits, and a radial assemblage of sinuous ridge landforms. We explore the origins of landforms in Chukhung crater, focusing in particular upon the sinuous ridges. In northern Chukhung crater, sinuous ridges extend downslope from fluvial valley systems on the northern crater wall. We interpret the northern sinuous ridges as inverted paleochannels: ridges formed by exhumation of resistant and/or indurated fluvial channel fill deposits. The origins of sinuous ridges on the southern floor of Chukhung crater are more ambiguous. They emerge from beneath moraine-like ridges which bound extant debris-covered glaciers extending from the southern wall of the crater. The southern sinuous ridges have numerous morphological and contextual similarities to eskers: ridges of glaciofluvial sediment deposited in meltwater conduits within or beneath wet-based glaciers. The close proximity of the northern and southern sinuous ridges, however, calls into question an interpretation which ascribes a different origin to each set. The similarity in the overarching process between esker and inverted channel formation (i.e., exposure by the removal of a bounding medium, be that ice or sediments/rock) results in convergence of form between eskers and inverted paleochannels. We discuss the esker-like characteristics of the southern sinuous ridges in detail, and argue that one of two ridge populations in southern Chukhung crater is best explained by the esker hypothesis while the other could be explained under either the esker or the inverted paleochannel hypothesis. Regardless of the specific formation mechanism for the southern sinuous ridges, we find that Chukhung crater has undergone significant modification by liquid water since its formation. The northern sinuous ridges and associated crater-wall valleys provide evidence for subaerial drainage of precipitation and/or snowmelt. This suggests that Chukhung crater, and possibly the surrounding region, experienced unusually warm and wet episodes between the early Hesperian and mid Amazonian. If some or all of the southern sinuous ridges are eskers, they could provide evidence for an additional influence of glacial meltwater in Chukhung crater during the mid-to-late Amazonian. If wet-based glaciation did occur in Chukhung crater, the location of the crater between major branches of the Tempe Fossae tectonic rift system would add to the growing body of evidence that elevated geothermal heat flux was an important driver of localized occurrences of recent wet-based glaciation on Mars.

Martian araneiform terrain, located in the Southern polar regions, consists of features with central pits and radial troughs which are thought to be associated with the solid state greenhouse effect under a CO$_{2}$ ice sheet. Sublimation at the base of this ice leads to gas buildup, fracturing of the ice and the flow of gas and entrained regolith out of vents and onto the surface. There are two possible pathways for the gas: through the gap between the ice slab and the underlying regolith, as proposed by Kieffer et al (2007), or through the pores of a permeable regolith layer, which would imply that regolith properties can control the spacing between adjacent spiders, as suggested by Hao et al. We test this hypothesis quantitatively in order to place constraints on the regolith properties. Based on previously estimated flow rates and thermophysical arguments, we suggest that there is insufficient depth of porous regolith to support the full gas flow through the regolith. By contrast, free gas flow through a regolith--ice gap is capable of supplying the likely flow rates for gap sizes on the order of a centimetre. This size of gap can be opened in the centre of a spider feature by gas pressure bending the overlying ice slab upwards, or by levitating it entirely as suggested in the original Kieffer et al (2007) model. Our calculations therefore support at least some of the gas flowing through a gap opened between the regolith and ice. Regolith properties most likely still play a role in the evolution of spider morphology, by regolith cohesion controlling the erosion of the central pit and troughs, for example., Comment: Accepted in Icarus

CoPhyLabLaboratory experiments are of major importance to understand the activity of comets and to support future space missions. However, past comet simulation experiments were performed under the assumption that comets are mainly composed of water ice with only a limited amount of dust. In the past years, however, the Rosetta mission has shown that cometary nuclei consist primarily of dust and less volatile materials are present than previously thought. Hence, it is high time to set up a new series of laboratory experiments with the aim to investigate the physics of realistic cometary analogue materials. This task is currently addressed by the CoPhyLab (Comet Physics Laboratory) which is a joint project among different partner institutions. This laboratory aims at studying the physics of cometary analogue materials. This task is approached by firstinvestigating isolated physical properties in so-called small experiments (S experiments). In a next step, the experiment’s complexity is increased step-by-step by either adding further components to the sample, or by studying several physical properties under different conditions (large experiments, which will be performed in the L chamber). S1: the tensile strength of organic materialsThe knowledge of the tensile strength of the cometary surface is of key importance to better understand the activity of comets. The tensile strength determines the strain required to detach material from the surface. As organic materials are ubiquitous in space, they could have played an important role during the planet formation process and are most likely incorporated into cometary nuclei. This S experiment campaign provides new measurements on the tensile strength of various granular organic materials. These materials are investigated by the Brazilian Disc Test and the measured values are normalised to a grain size of one micrometer and a volume filling factor of 0.5 for better comparability. The experiments show that the tensile strength of organic materials ranges over four orders of magnitude. Graphite and paraffin have much higher tensile strengths values compared to silica, whereas the tensile strength of coals is very low. This work demonstrates that organic materials are not generally stickier than silicates, or water ice. S2: gas permeability of analogue materials The cometary nucleus is made of water ice, organics and silicateous dust and the ice is trapped inside the matrix of non-volatiles. Hence, the evolving gas has to stream away from its originating region inside the surface layers towards the surface. This work package has the aim to investigate the gas transport mechanisms through porous cometary analogue materials. Therefore, gas flow measurements are performed to investigate the permeability of several materials, which are chosen to mimic cometary surface properties. With these measurements, the gas permeability and the Knudsen diffusion coefficient of the sample materials are obtained. These simulants are tested with respect to different filling heights, packing properties and grain shapes. The gas flow experiments show that the grain size distribution and the packing density of the samples are primarily influencing the permeability of the sample. S3: thermal conductivity of analogue materialsMeasurements of the thermal properties of analogue materials are essential in interpreting remote sensing data and the findings of in-situ instruments. The thermal properties of the subsurface layers determine the surface temperature of asteroids and comets. The temperature stratification inside planetary object is a key parameter to understand the processing of their interior. This experiment campaign is dedicated to measure the thermal properties of analogue materials. In preparation for these measurements we have set up a small vacuum chamber equipped with an infrared camera and temperature sensors. The samples are illuminated for a short duration by a laser. We then compare the measured temperature profiles with the predictions of a thermophysical model to determine the thermal conductivity of the samples. S4: ejection of materialWhen comets approach the Sun, the sublimation pressure will be reached inside the material. If the tensile strength is exceeded by the evolving pressure, the particles can be ejected from the cometary surface and are accelerated. However, the details of the dust dynamics close to the surface are not understood in detail. The idea of this S experiment campaign is to develop an experimental routine to track ejected particles from a sample composed of granular water ice. Therefore, we recorded the power of the illumination, the temperature of the sample and measured the particle trajectories with an high speed camera. Furthermore, the experiments are also simulated by a thermophysical model. Our experiments show that samples composed of pure granular water ice can eject water-ice particles by the pressure build up of water vapour in their interior. Compressed samples posses an higher activity level (ejection events per second) compared to uncompressed samples. The ejected particles have a non-zero initial velocity which is most probably caused by a very fast acceleration of the particles before the first data point is recorded by the camera. The L chamberThe core of this project is the realisation of a comet simulation chamber which will be capable to utilise multiple instruments to monitor and measure the sample properties before, during and after the experiment campaigns. This chamber will be used to perform long duration experiments at low temperatures and low pressures. At this stage (end of June, 2020), the chamber is already installed in place and is vacuum tight, the cooling shield is assembled and the sample carrier cart as well as the self-made glove box are ready to use. The next steps comprise the integration of the cooling shield and the main cooling system. We foresee to run the first experiments in approximately six weeks from now. During the EPSC conference we will provide a technical overview of the chamber and we will present the first experiments performed in the L chamber. AcknowledgementsThis work was carried out in the framework of the CoPhyLab project funded by the D-A-CH programme (GU 1620/3-1 and BL 298/26-1 / SNF 200021E 177964 / FWF I 3730-N36). DB and JB thank the Deutsches Zentrum f\"ur Luft- und Raumfahrt for support under grant 50WM1846.

The penetration depth of broad spectrum solar irradiation over the wavelength range 300 nm – 1100 nm has been experimentally measured for water and carbon dioxide ices of different grain size ranges. Both of these ice compositions are found on the surface of Mars, and have been observed as surface frosts, snow deposits and ice sheets. The e‐folding scale of snow and slab ice has been previously measured, but understanding the behaviour between these end‐member states is important for modelling the thermal behaviour and surface processes associated with ice deposits on Mars, such as grain growth and slab formation via sintering, and carbon dioxide jetting leading to the formation of araneiforms. We find the penetration depth increases in a predictable way with grain size, and an empirical model is given to fit this data, varying with both ice composition and grain size.

Icy surfaces behave differently to rocky or regolith‐covered surfaces in response to irradiation. A key factor is the ability of visible light to penetrate partially into the subsurface. This results in the Solid‐State Greenhouse Effect (SSGE), as ices can be transparent or translucent to visible and shorter wavelengths, whilst opaque in the infrared. This can lead to significant differences in shallow sub‐surface temperature profiles when compared to rocky surfaces. Of particular significance for modelling the SSGE is the e‐folding scale, otherwise known as the absorption scale length, or penetration depth, of the ice. Whilst there have been measurements for water ice and snow, pure and with mixtures, to date there have been no such measurements published for carbon dioxide ice. After an extensive series of measurements we are able to constrain the e‐folding scale of CO2 ice for the cumulative wavelength range 300 nm to 1100 nm, which is a vital parameter in heat transfer models for the Martian surface, enabling us to better understand surface‐atmosphere interactions at Mars’ polar caps.

International audience; We present a systematic, metre-scale characterisation of the 3D morphometry of an esker on Mars, and the first attempt to reconstruct the multi-stage dynamics of esker formation on Mars. Eskers are sinuous ridges comprising sediment deposited by meltwater draining through ice-confined tunnels within or beneath glaciers. Detailed morphometric insights into eskers on Mars are important for (i) informing morphometric tests of whether sinuous ridges elsewhere on Mars are eskers, and (ii) informing modelling experiments which aim to reconstruct the glaciological and environmental controls on esker formation on Mars. We use a digital elevation model generated from High Resolution Imaging Science Experiment (HiRISE) images to characterise the height and width of an extremely rare esker associated with a late-Amazonian-aged viscous flow feature (debris-covered glacier) in NW Tempe Terra, Mars. Our measurements suggest that the NW Tempe Terra esker is a 'stacked' formation comprising an underlying 'lower member' ridge that is superposed by a narrower 'upper member' ridge. We used a novel morphometric approach to test whether the apparent stacking records two distinct esker deposition regimes (either within the same drainage episode, or within temporally-separated drainage episodes). This approach posits that esker crest morphology is controlled by primary esker formation processes and, by extension, that portions of eskers with similar crest morphologies should have similar morphometric relationships. We predicted the morphometric relationships described by the constituent upper and lower member ridges based on 'reference relationships' observed for morphologically-similar portions of the esker where no evidence of stacking was observed. Our observations corresponded well with the predicted relationships, supporting our stacked esker hypothesis. We propose conceptual models, which invoke spatial and temporal variations in sediment supply and meltwater discharge, to explain the stacked morphology. These models are informed by morpho-sedimentary relationships observed along eskers on Earth.

Accepted: 2019-07-08, 資料番号: SA1190149000

著者人数: 37名 (所属. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS): 岡田, 達明; 坂谷, 尚哉; 田中, 智; 矢野, 創), Number of authors: 37 (Affiliation. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS): Okada, Tatsuaki; Sakatani, Naoya; Tanaka, Satoshi; Yano, Hajime）, Accepted: 2019-06-04, 資料番号: SA1190164000

International audience; Carbonaceous (C-type) asteroids1 are relics of the early Solar System that have preserved primitive materials since their formation approximately 4.6 billion years ago. They are probably analogues of carbonaceous chondrites2,3 and are essential for understanding planetary formation processes. However, their physical properties remain poorly known because carbonaceous chondrite meteoroids tend not to survive entry to Earth’s atmosphere. Here we report on global one-rotation thermographic images of the C-type asteroid 162173 Ryugu, taken by the thermal infrared imager (TIR)4 onboard the spacecraft Hayabusa25, indicating that the asteroid’s boulders and their surroundings have similar temperatures, with a derived thermal inertia of about 300 J m−2 s−0.5 K−1 (300 tiu). Contrary to predictions that the surface consists of regolith and dense boulders, this low thermal inertia suggests that the boulders are more porous than typical carbonaceous chondrites6 and that their surroundings are covered with porous fragments more than 10 centimetres in diameter. Close-up thermal images confirm the presence of such porous fragments and the flat diurnal temperature profiles suggest a strong surface roughness effect7,8. We also observed in the close-up thermal images boulders that are colder during the day, with thermal inertia exceeding 600 tiu, corresponding to dense boulders similar to typical carbonaceous chondrites6. These results constrain the formation history of Ryugu: the asteroid must be a rubble pile formed from impact fragments of a parent body with microporosity9 of approximately 30 to 50 per cent that experienced a low degree of consolidation. The dense boulders might have originated from the consolidated innermost region or they may have an exogenic origin. This high-porosity asteroid may link cosmic fluffy dust to dense celestial bodies1

著者人数: 120名(所属. 宇宙航空研究開発機構宇宙科学研究所 (JAXA)(ISAS): 澤田, 弘崇; 横田, 康弘; 坂谷, 尚哉; 岡田, 達明; 田中, 智; 飯島, 祐一; 早川, 雅彦; 松岡, 萌; R.-L. Ballouz; 嶌生, 有理; 水野, 貴秀; 石原, 吉明; 長谷川, 直; 藤本, 正樹; 吉川, 真; 山本, 幸生; 白井, 慶; R. Noguchi; 尾川, 順子; 照井, 冬人; 菊地, 翔太; 山口, 智宏; 竹内, 央, 三桝, 裕也; 高橋, 忠輝; 竹井, 洋; 藤井, 淳; 中澤, 暁; 細田, 聡史; 森, 治; 嶋田, 貴信; Soldini, Stefania; 岩田, 隆浩; 安部, 正真; 矢野, 創; 月崎, 竜童; 尾崎, 正伸; 西山, 和孝; 佐伯, 孝尚; 渡邊, 誠一郎; 津田, 雄一), Accepted: 2019-03-12, 資料番号: SA1180387000

The depth to which solar radiation can penetrate through ice is an important factor in understanding surface‐atmosphere interactions for icy planetary surfaces. Mars hosts both water and carbon dioxide ice on the surface and in the subsurface. At high latitudes during autumn and winter carbon dioxide condenses to form the seasonal polar cap. This has been both modelled and observed to, in part, occur as snowfall. As snow accumulates, the thermal properties of the surface are changed, whether the underlying surface was rocky, regolith or a solid ice sheet. This results in a change (usually increase) in albedo, affecting the proportion of the incident solar energy reflected, or transmitted below the surface of the snow layer. The depth to which light can penetrate through this layer is an important parameter in heat transfer models for the Martian surface, and is often quantified using the e‐folding scale. We present the first measurements of the e‐folding scale in pure carbon dioxide snow for the wavelengths 300 nm to 1100 nm alongside new measurements of water snow.

As Viking Lander 1 touched down on Mars one of its footpads fully penetrated a patch of loose fine-grained drift material. The surrounding landing site, as observed by VL-1, was found to exhibit a complex terrain consisting of a crusted surface with an assortment of rocks, large dune-like drifts and smaller patches of drift material. We use a temperature sensor attached to the buried footpad and covered in fine-grained material to determine the thermal properties of drift material at the VL-1 site. The thermal properties are used to investigate the microstructure of the drift material and understand its relevance to surface-atmosphere interactions. We obtained a thermal inertia value of 103 ± 22 tiu. This value is in the upper range of previous thermal inertia estimates of martian dust as measured from orbit and is significantly lower than the regional thermal inertia of the VL-1 site, of around 283 tiu, obtained from orbit. We estimate a thermal inertia of around 263 ± 29 tiu for the duricrust at the VL-1 site. It was noted the patch of fine-grained regolith around the footpad was about 20-30 K warmer compared to similar material beyond the thermal influence of the lander. An effective diameter of 8 ± 5 μm was calculated for the particles in the drift material. This is larger than atmospheric dust and large compared to previous estimates of the drift material particle diameter. We interpret our results as the presence of a range of particle sizes

International audience; Martian gullies were initially hypothesized to be carved by liquid water, due to their resemblance to gullies on Earth. Recent observations have highlighted significant sediment transport events occurring in Martian gullies at times and places where CO 2 ice should be actively sublimat-ing. Here we explore the role of CO 2 sublimation in mobilizing sediment through laboratory simulation. In our previous experimental work, we reported the first observations of sediment slope movement triggered by the sublimation of CO 2 frost. We used a Mars regolith simulant near the angle of repose. The current study extends our previous work by including two additional substrates, fine and coarse sand, and by testing slope angles down to 10°. We find that the Mars regolith sim-ulant is active down to 17°, the fine sand is active only near the angle of repose and the coarse sand shows negligible movement. Using an analytical model, we show that under Martian gravity motion should be possible at even lower slope angles. We conclude that these mass-wasting processes could be involved in shaping Martian gullies at the present day and intriguingly the newly reported CO 2-creep process could provide an alternative explanation for putative solifluction lobes on Mars.

In this investigation, HiRISE images were surveyed across three regions of the Northern Plains of Mars; Acidalia, Arcadia and Utopia Planitiae. A sample of HiRISE images within each of these areas was examined. The aim of the investigation was to determine the distribution of three varieties of landform; clastic patterned ground, lobate hill-slope features and scalloped depressions. These features are of importance, as they are morphologically similar to terrestrial periglacial features.\ud \ud Examples of these landforms were found across the study areas. Scalloped depressions are common at mid latitudes in each of the three regions. Sorted patterned ground was not as widespread. Some examples of sorted patterned ground were found in all three study areas, but the main concentration occurs in the north-western region of Acidalia Planitia. Lobate hill-slope features were the least common of the three landform types. Despite occurring infrequently, several possible examples of lobate features were found to occur in proximity to other putative periglacial features.\ud \ud It was found that lobate hill-slope features and clastic patterns occurred further south than expected, beyond the southern extent of many previous studies. These features, and by extension the processes that form them, could thus occur more widely than previously thought.\ud \ud It also appears that although putative periglacial features are often found in crater interiors they are not limited to these environments. Extensive areas of patterned ground were found on the inter-crater plains. Lobate features and sorted stripes were often found on crater walls, which would support the hypothesis that they are analogous to hill-slope features on Earth. Scalloped depressions were most often found in crater interiors, or on crater ejecta, although examples on the inter crater plains were not uncommon.

Our interpretation of the data returned by Rosetta and other cometary missions is based on the predictions of theoretical models and the results of laboratory experiments. For example, Kossacki et al. (2015) showed that 67P's surface hardness reported by Spohn et al. (2015) can be explained by sintering. The present work supports Rosetta's observations by investigating the hardening process of the near-surface layers and the change in surface morphology during insolation. In order to create as simple an analogue as possible our sample consists of pure, porous H2O ice and carbon black particles. The observations suggest that translucence of the near-surface ice is important for enabling subsurface hardening. As an end product of our experiments we also obtained carbon agglomerates with some residual strength.

From the operation of the MUPUS thermal probe Spohn et al. (2015) concluded that the material of the nucleus of 67P/Churyumov–Gerasimenko is likely to have a high strength, at least locally at the Philae landing site. In this work we consider the derived strength of the material in order to constrain its granulation. For this purpose we performed numerical simulations of the long-term sintering of ice–dust granular mixtures of different granulation, covered by a dust mantle. The dust mantle has a thickness of 0–16cm, and a (pore size and temperature-dependent) thermal conductivity. According to our simulations a hardened layer at least a meter thick forms beneath the dust only when the grains are tens of microns in radius, or smaller.

International audience; This article discusses relevant physical properties of the regolith at the Mars InSight landing site as understood prior to landing of the spacecraft. InSight will land in the northern lowland plains of Mars, close to the equator, where the regolith is estimated to be ≥3--5 m thick. These investigations of physical properties have relied on data collected from Mars orbital measurements, previously collected lander and rover data, results of studies of data and samples from Apollo lunar missions, laboratory measurements on regolith simulants, and theoretical studies. The investigations include changes in properties with depth and temperature. Mechanical properties investigated include density, grain-size distribution, cohesion, and angle of internal friction. Thermophysical properties include thermal inertia, surface emissivity and albedo, thermal conductivity and diffusivity, and specific heat. Regolith elastic properties not only include parameters that control seismic wave velocities in the immediate vicinity of the Insight lander but also coupling of the lander and other potential noise sources to the InSight broadband seismometer. The related properties include Poisson’s ratio, P- and S-wave velocities, Young’s modulus, and seismic attenuation. Finally, mass diffusivity was investigated to estimate gas movements in the regolith driven by atmospheric pressure changes. Physical properties presented here are all to some degree speculative. However, they form a basis for interpretation of the early data to be returned from the InSight mission.

Heat flow is an important constraint on planetary formation and evolution. It has been suggested that Martian obliquity cycles might cause periodic collapses in atmospheric pressure, leading to corresponding decreases in regolith thermal conductivity (which is controlled by gas in the pore spaces). Geothermal heat would then build up in the subsurface, potentially affecting present-day heat flow - and thus the measurements made by a heat-flow probe such as the InSight HP$^{3}$ instrument. To gauge the order of magnitude of this effect, we model the diffusion of a putative heat pulse caused by thermal conductivity changes with a simple numerical scheme and compare it to the heat-flow perturbations caused by other effects. We find that an atmospheric collapse to 300 Pa in the last 40 kyr would lead to a present-day heat flow that is up to $2-8\%$ larger than the average geothermal background. Considering the InSight mission with expected $5-15\%$ error bars on the HP$^{3}$ measurement, this perturbation would only be significant in the best-case scenario of full instrument deployment, completed measurement campaign, and a well-modelled surface configuration. The prospects for detecting long-term climate perturbations via spacecraft heat-flow experiments remain challenging., Comment: 13 pages, 5 figures, accepted in PSS

We compare measurements made by two impact penetrometers of different sizes and with different tip shapes to further understand penetrometer design for performing penetrometry on an asteroid. To this end we re-visit the interpretation of data from the Huygens’ penetrometer, ACC-E, that impacted Titan’s surface. In addition we investigate the potential of a spacecraft fitted with a penetrometer to bounce using a test rig, built at The Open University (UK). Analysis of ACC-E laboratory data, obtained from impacts into ∼4 mm diameter gravel, was found to produce an unusual decrease in resistance with depth (force–depth gradient) which was also seen in the Huygens’ ACC-E data from Titan and originally interpreted as a wet or moist sand. The downward trend could also be reproduced in a hybrid Discrete Element Model (DEM) if it was assumed that the near surface particles are more readily mobilised than those deeper in the target. With regard to penetrometer design penetration resistance was found to be sensitive to the ratio of particle to tip diameter. A clear trend was observed with a conical tip penetrometer, X-PEN, of decreasing force–depth gradients with increasing particle sizes most likely due to a transformation from a bulk displacement of material by the penetrating tip to more local interactions. ACC-E, which has a hemispherical tip, was found to produce a wider range of force–depth gradients than X-PEN, which had a conical tip, possibly due to difficulties dislodging jammed particles. Both penetrometers were able to determine particle diameter and mass after post-processing of the data. Laboratory simulations of landings with the test rig suggest that a large impact penetrometer under certain circumstances could absorb a significant amount of the elastic energy of the spacecraft possibly aiding landing. Alternatively a small impact penetrometer would allow the spacecraft to bounce freely off the surface to make a measurement at another location.

We present the scientific case for inclusion of penetrators into the Europan surface, and the candidate instruments which could significantly enhance the scientific return of the joint ESA/NASA Europa-Jupiter System Mission (EJSM). Moreover, a surface element would provide an exciting and inspirational mission highlight which would encourage public and political support for the mission. Whilst many of the EJSM science goals can be achieved from the proposed orbital platform, only surface elements can provide key exploration capabilities including direct chemical sampling and associated astrobiological material detection, and sensitive habitability determination. A targeted landing site of upwelled material could provide access to potential biological material originating from deep beneath the ice. Penetrators can also enable more capable geophysical investigations of Europa (and Ganymede) interior body structures, mineralogy, mechanical, magnetic, electrical and thermal properties. They would provide ground truth, not just for the orbital observations of Europa, but could also improve confidence of interpretation of observations of the other Jovian moons. Additionally, penetrators on both Europa and Ganymede, would allow valuable comparison of these worlds, and gather significant information relevant to future landed missions. The advocated low mass penetrators also offer a comparatively low cost method of achieving these important science goals. A payload of two penetrators is proposed to provide redundancy, and improve scientific return, including enhanced networked seismometer performance and diversity of sampled regions. We also describe the associated candidate instruments, penetrator system architecture, and technical challenges for such penetrators, and include their current status and future development plans.

The thermo-mechanical properties of planetary surface and subsurface layers control to a high extent in which way a body interacts with its environment, in particular how it responds to solar irradiation and how it interacts with a potentially existing atmosphere. Furthermore, if the natural temperature profile over a certain depth can be measured in situ, this gives important information about the heat flux from the interior and thus about the thermal evolution of the body. Therefore, in most of the recent and planned planetary lander missions experiment packages for determining thermo-mechanical properties are part of the payload. Examples are the experiment MUPUS on Rosetta's comet lander Philae, the TECP instrument aboard NASA's Mars polar lander Phoenix, and the mole-type instrument HP3 currently developed for use on upcoming lunar and Mars missions. In this review we describe several methods applied for measuring thermal conductivity and heat flux and discuss the particular difficulties faced when these properties have to be measured in a low pressure and low temperature environment. We point out the abilities and disadvantages of the different instruments and outline the evaluation procedures necessary to extract reliable thermal conductivity and heat flux data from in situ measurements., Highlights ► Numerical simulation of the thermal history of a planetary body. ► Development of robust thermal conductivity sensors for planetary applications. ► Measurement of the global heat flow of a planet or small planetary body.

A gradual shift in United Kingdom research funding from blanket financing by government agencies towards more diversified income streams through activities funded by various customers is prompting academic research institutions to orient their research portfolios accordingly. Academic organisations such as university institutes are increasingly relying on the funding obtained through research projects paid for by other customers than national funding bodies, thus diversifying their operations. Wrong choices in this diversification process can, however, have serious financial or operational implications for the organisation. A framework is proposed that should help enable academic institutes to rationalise their decision-making processes when seeking external funding for their operations through project grants or research contracts and learn from projects.

Thermal conductivity measurements, presented in this paper (Fig. 3), were made during the descent of the Huygens probe through the atmosphere of Titan below the altitude of 30 km. The measurements are broadly consistent with reference values derived from the composition, pressure and temperature profiles of the atmosphere; except in narrow altitude regions around 19 km and 11 km, where the measured thermal conductivity is lower than the reference by 1% and 2%, respectively. Only single data point exists at each of the two altitudes mentioned above; if true however, the result supports the case for existence for molecules heavier than nitrogen in these regions (such as: ethane, other primordial noble gases, carbon dioxide, and other hydrocarbon derivatives). The increasing thermal conductivity observed below 7 km altitude could be due to some liquid deposition during the descent; either due to condensation and/or due to passing through layers of fog/cloud containing liquid nitrogen–methane. Thermal conductivity measurements do not allow conclusions to be drawn about how such liquid may have entered the sensor, but an estimate of the cumulative liquid content encountered in the last 7 km is 0.6% by volume of the Titan's atmosphere sampled during descent.

While the surface missions to the Moon of the 1970s achieved a great deal, scientifically much was also left unresolved. The recent plethora of lunar missions (flown or proposed) reflects a resurgence in interest in the Moon, not only in its own right, but also as a record of the \ud early solar system including the formation of the Earth. Results from recent orbiter missions have shown evidence of ice or at least hydrogen within shadowed craters at the lunar poles.

Planetary heat flow probes measure heat flow (depth-resolved temperature and thermal conductivity) to provide insight into the internal state of a planet. The probes have been utilized extensively on Earth, twice on the Moon, and once on the Surface of comet 67P-CG. Mars is an important target for heat flow measurement as heat flow is a critical parameter in Martian thermal history models. Earlier studies indicate that Martian planetary heat flow can be accessed at 5m below the surface in dry regolith monitored over at least one Martian year. A one Martian year monitoring period is necessary because, in the shallow subsurface, heat flow from the interior is superposed with time varying heat flow contributions, primarily due to insolation. Given that a heat flow probe may not achieve its target depth or monitoring period, this study investigates how the depth (2–5m), duration (0–1 Martian year) and quality of measurements influence the accuracy of planetary heat flow. An inverse model is used to show that, in the preceding scenarios, the accuracy of planetary heat flow directly estimated from depth-dependent thermal conductivity with 10–20% precision errors, temperatures with 50–100mK precision errors and modelling uncertainties up to 500mK, can, on average, be improved by a factor of 27 with optimization to 13%. Accuracies increase with sensor penetration depth and regolith monitoring period. Heat flow optimized from instantaneous measurements or those with the shortest regolith monitoring periods have increased accuracy where the frequency and amplitude of the temperature variation are lowest. The inverse model is based on the Function Specification Inversion method. This study demonstrates that a solution subspace can be identified within a space of uncertainties modelled for the temperature measurements and planetary heat flow: the subspace is defined by a constant log-ratio of their respective standard deviations. Optimized heat flow estimates display reduced correlation with increasing temperature precision and systematic conductivity errors, with the constraint of other known model parameters. Consequently, the model permits upper bounds to be placed on the conductivity estimate without conductivity optimization, as heat flows are optimized to a limiting value with increasing systematic conductivity errors for any given parameter set. Overall, the results demonstrate a 52% chance of achieving a direct heat flow estimate accurate to within 40%, with the same being 82% after optimization. © 2016 Elsevier Ltd

The Huygens probe underwent vigorous short-period motions during its parachute descent through the atmosphere of Saturn's moon Titan in January 2005, at least some of which were excited by the Titan environment. Several sensors in the Huygens Surface Science Package (SSP) detect these motions, indicating the transition to the smaller stabilizer parachute, the changing probe spin rate, aerodynamic buffeting, and pendulum motions. Notably, in an altitude range of about 20–30 km where methane drops will freeze, the frequency content and statistical kurtosis of the tilt data indicate excitation by turbulent air motions like those observed in freezing clouds on Earth, supporting the suggestion of Tokano et al. [Tokano, T., McKay, C.P., Neubauer, F.M., Atreya, S.K., Ferri, F., Fulchignoni, M., Niemann, H.B. (2006a). Methane drizzle on Titan. Nature 442, 432–435] that the probe passed through such a cloud layer. Motions are weak below 20 km, suggesting a quiescent lower atmosphere with turbulent fluctuations of nominally

Aboard the Huygens probe, which descended through Titan's atmosphere in January 2005, was the Surface Science Package (SSP), a set of 9 sensors, including a speed-of-sound sensor. We present the first detailed description of the SSP speed of sound measurements and report constraints on the methane content in Titan's lower atmosphere based on these measurements. After a careful calibration and subsequent Bayesian analysis, our measurements yield a most likely methane fraction in Titan's lower atmosphere of approximately 2% at 10 km, increasing to 3.5% at lower altitudes, based on a binary composition. Our data show that any large scale variation of methane within the lower 11 km of Titan's atmosphere is unlikely. Within experimental and theoretical uncertainties, our results are compatible with earlier estimates obtained from the GCMS experiment [Niemann, H.B., Atreya, S.K., Bauer, S.J., Carignan, G.R., Demick, J.E., Frost, R.L., Gautier, D., Haberman, J.A., Harpold, D.N., Hunten, D.M., Israel, G., Lunine, J.I., Kasprzak, W.T., Owen, T.C., Paulkovich, M., Raulin, F., Raaen, E., Way, S.H., 2005. Nature 438 (7069), 779–784].

This paper outlines the method of measurement and analysis of the thermal conductivity instrument (THP) that has successfully returned measurements from the atmosphere of Saturn’s moon Titan during the descent of the Huygens probe on 14th January 2005. The technique is validated by analysing laboratory calibration data gathered by our instrument in three pure gases (nitrogen, methane, and ethane) over Titan’s temperature range (90 to 180 K). Calibration results show errors

We present the results from the first sonar to be deployed outside of Earth, and the first active acoustic instrument on Titan, onboard the Huygens probe, and the implications of its data for the geomorphology and characteristics of the Huygens landing site. Signals were recorded from 90 m downwards until impact, with a maximum sensor footprint diameter at the ground of 39.2 m. Probe impact speed was measured to be 4.67 m s−1. Derivation of terrain topography in a transect beneath the probe may indicate a ridge-trough terrain with an amplitude of about 1 m and a wavelength of about 10 m, although a flat surface is also consistent with the results. Modelling of the returned signal indicates that the surface acoustic properties at the landing site must be specular in nature, which may have two possible (not incompatible) causes—the surface may consist of sorted interlocking grains, smooth on the centimetre scale, which would imply either fluvial sorting or the infill of small particles interstitial to the larger particles (similar to a terrestrial playa). Alternatively, specularity may indicate the presence of methane as an interstitial liquid or as very small pools. Due to mission constraints, tens of metres around the landing site were not well-imaged by Huygens' cameras except for the narrow azimuth observed after impact (the camera did not look straight down, and was not in imaging mode during the last few hundred metres of descent). Thus the data presented are among the few direct observations of the landing site surroundings.

The speed of sound in a gas can be used to identify its composition, as has been done on the Earth. We show that, unlike in terrestrial applications, the third virial coefficient cannot be neglected in cold and dense atmospheres. We derive a model for the speed of sound of pure gases and gas mixtures at low temperatures and high pressures, based on the virial equation. After comparing the results of our model to measured data, we apply our model to the atmosphere of Titan. The difference between our third-order virial expansion and the commonly used second-order expansion is significant, showing that the third virial coefficient needs to be taken into account when accurate speed-of-sound measurements are used to derive atmospheric properties under Titan conditions.

With Huygens’ descent into Titan’s atmosphere drawing nearer, the composition and state of Titan’s surface remained largely unknown. The idea of a global ocean on Titan has become less popular over the last decade, though the possibility of lakes and seas has remained, and recently [Campbell, D.B., Black, G.J., Carter, L.M., Ostro, S.J. Radar evidence for liquid surfaces on Titan. Science 302, 431–434, 2003] reported radar evidence for liquid surfaces. Ground truth for the existence of an ocean, sea or lake on Titan or, more precisely, a liquid surface at the specific impact point of the Huygens probe, came from the sensors of the Huygens Surface Science Package (SSP). The state of the surface material can be derived on impact using the onboard accelerometers. In the case of an impact into a liquid the SSP sensors would have been able to measure not only density but also acoustic properties, permittivity, refractive index and thermal properties. In this work, we describe possible ways of constraining the composition of a liquid surface on Titan by combining various measurements made by SSP.

We present a method for inferring the relative molar abundance of constituents of a liquid mixture, in this case methane, ethane, nitrogen and argon, from a measurement of a set of physical properties of the mixture. This problem is of interest in the context of the Huygens Surface Science Package, SSP, equipped to measure several physical properties of a liquid in case of a liquid landing on Saturn's moon Titan. While previous models emphasized the possibility of verifying a certain model proposed by atmospheric composition and equations of state, we use an inverse approach to the problem, i.e. we will infer the liquid composition strictly from our measurements of density, refractive index, permittivity, thermal conductivity and speed of sound. Other a priori information can later be used to improve (or reject) the model obtained from these measurements.

Thermal and mechanical material properties determine comet evolution and even solar system formation because comets are considered remnant volatile-rich planetesimals. Using data from the Multipurpose Sensors for Surface and Sub-Surface Science (MUPUS) instrument package gathered at the Philae landing site Abydos on comet 67P/Churyumov-Gerasimenko, we found the diurnal temperature to vary between 90 and 130 K. The surface emissivity was 0.97, and the local thermal inertia was 85 ± 35 J m −2 K −1 s -1/2 . The MUPUS thermal probe did not fully penetrate the near-surface layers, suggesting a local resistance of the ground to penetration of >4 megapascals, equivalent to >2 megapascal uniaxial compressive strength. A sintered near-surface microporous dust-ice layer with a porosity of 30 to 65% is consistent with the data.

In this article, we present a method to measure the relative changes in the magnetic susceptibility of rock samples in the low-temperature range (−200 °C to +20 °C). The method differs from other experimental methods currently used in that it requires—in contrast to ac bridges, the most widely used devices—very little sophisticated laboratory equipment: A high-precision laboratory balance, a Pt-100 thermoelement and a computer with standard input/output interface and analog/digital processing capabilities, as well as a few rare earth magnets, are the only devices needed in addition to standard laboratory equipment. A Dewar container and a few plexiglass panes can either be handcrafted in the workshops of any larger research institute or are commercially available at little cost. The results of our measurements reveal that the temperature-varying magnetic properties of rock samples can be reliably observed.

European Space Agencies fifth cornerstone mission BepiColombo includes a ‘Surface Element’ to land a scientific payload on the surface of Mercury. The current strawman payload includes a heat flow and physical properties package (HP3), focussing on key thermal and mechanical properties of the near-surface material (down to a depth of 2– 5 m ) and the measurement of heat flow from Mercury's interior, an important constraining parameter for models of the planet's interior and evolution. We present here an overview of the HP3 experiment package and its possible accommodation in a self-inserting ‘mole’ device. A mole is considered to be the most appropriate deployment method for HP3, at least in the currently-assumed case of an airbag-assisted soft landing architecture for the Mercury Surface Element.

Objective: Characterize and understand acoustic instrument performance on the surface of Titan.\ud \ud Methods: The Huygens probe measured the speed of sound in Titan's atmosphere with a 1 MHz pulse time-of-flight transducer pair near the bottom of the vehicle. We examine the fraction of pulses correctly received as af unction of time.\ud \ud Results: This system returned good data from about 11 km altitude, where the atmosphere became thick enough to effectively transmit the sound, down to the surface just before landing: these data have been analyzed previously. After an initial transient at landing, the instrument operated nominally for about 10 min, recording pulses much as during descent. The fraction of pulses detected then declined and the transmitted sound ceased to be detected altogether, despite no indication of instrument or probe configuration changes.\ud \ud Conclusions: The most likely explanation appears to be absorption of the signal by polyatomic gases with relaxation losses at the instrument frequency, such as ethane, acetylene and carbon dioxide. These vapors, detected independently by the GCMS instrument, were evolved from the surface material by the warmth leaking from the probe, and confirm the nature of the surface materials as ‘damp’ with a cocktail of volatile compounds. Some suggestions for future missions are considered.\ud \ud Practice implications: None.

The Medusae Fossae Formation (MFF) is a geological formation comprising three geological units (members) spread across five principal lobes. It dominates a quarter of the longitudinal extent of the equatorial region of Mars. Positive relief features referred to as ‘sinuous ridges’ (commonly interpreted as inverted paleoflow channel or valley fills) have been observed in the lowest member of the western MFF, but have not been identified within the central and eastern portions of the formation, in the middle and upper members. This paper presents the identification and analysis of a branching, positive relief system which occurs in the central lobe of the MFF in what appears to be an exposure of the middle member. A simple geomorphological map of the system is presented, from which we have adopted the working hypothesis that this is an inverted fill of a branching fluvial channel or valley system. A suite of morphological and topographic evidence supporting this hypothesis is presented, including analysis of the network using a ∼15 m/pixel digital terrain model derived from a Context Imager (CTX) stereo image pair. The evidence supporting this hypothesis includes: (1) the local slope and topography of the upper surface of the network are consistent with a contributory network; (2) the braided, fan-like form at the termination of the branching network is consistent in morphology with it being a depositional fan at the end of a fluvial system; (3) the terminal fan and surrounding deposits show layering and polygonization; and (4) there is strong association between the lower order branches and amphitheater shaped scarps in the depression walls. We evaluate the possible origins of this fluvial system and suggest that seepage sapping is the most probable. Two possible models for the evolution of the network and related features are presented; both require melt of ice within the MFF to form liquid water. We conclude that at least some portions of the Medusae Fossae Formation, if not the entire formation, were once volatile-rich. Finally, we note that our observations do not rule out the case that this network formed before MFF emplacement, and has since been exhumed. However, this conclusion would suggest that much of the surrounding terrain, currently mapped as middle-member MFF, is not in fact MFF material at all.

Emplacement of four or more kinetic penetrators geographically distributed over the lunar surface can enable a broad range of scientific exploration objectives of high priority and provide significant synergy with planned orbital missions. Whilst past landed missions achieved a great deal, they have not included a far-side lander, or investigation of the lunar interior apart from a very small area on the near side. Though the LCROSS mission detected water from a permanently shadowed polar crater, there remains in-situ confirmation, knowledge of concentration levels, and detailed identification of potential organic chemistry of astrobiology interest. The planned investigations will also address issues relating to the origin and evolution of the Earth–Moon system and other Solar System planetary bodies. Manned missions would be enhanced with use of water as a potential in-situ resource; knowledge of potential risks from damaging surface Moonquakes, and exploitation of lunar regolith for radiation shielding. LunarNet is an evolution of the 2007 LunarEX proposal to ESA (European Space Agency) which draws on recent significant advances in mission definition and feasibility. In particular, the successful Pendine full-scale impact trials have proved impact survivability for many of the key technology items, and a penetrator system study has greatly improved the definition of descent systems, detailed penetrator designs, and required resources. LunarNet is hereby proposed as an exciting stand-alone mission, though is also well suited in whole or in-part to contribute to the jigsaw of upcoming lunar missions, including that of a significant element to the ILN (International Lunar Network).

About the book: This invaluable volume set of Advances in Geosciences continues the excellent tradition of the Asia-Oceania scientific community in providing the most up-to-date research results on a wide range of geosciences and environmental science. The information is vital to the understanding of the effects of climate change, extreme weathers on the most populated regions and fastest moving economies in the world. Besides, these volumes also highlight original papers from many prestigious research institutions which are doing cutting edge study in atmospheric physics, hydrological science and water resource, ocean science and coastal study, planetary exploration and solar system science, seismology, tsunamis, upper atmospheric physics and space science.