The MetNet vehicle: a lander to deploy environmental stations for local and global investigations of Mars

Investigations of global and related local phenomena on Mars such as atmospheric circulation patterns, boundary layer phenomena, water, dust and climatological cycles and investigations of the planetary interior would benefit from simultaneous, distributed in situ measurements. Practically, such an observation network would require low-mass landers, with a high packing density, so a large number of landers could be delivered to Mars with the minimum number of launchers. The Mars Network Lander (MetNet Lander; MNL), a small semi-hard lander/penetrator design with a payload mass fraction of approximately 17 %, has been developed, tested and prototyped. The MNL features an innovative Entry, Descent and Landing System (EDLS) that is based on inflatable structures. The EDLS is capable of decelerating the lander from interplanetary transfer trajectories down to a surface impact speed of 50-70 ms(-1) with a deceleration of < 500 g for < 20 ms. The total mass of the prototype design is approximate to 24 kg, with approximate to 4 kg of mass available for the payload. The EDLS is designed to orient the penetrator for a vertical impact. As the payload bay will be embedded in the surface materials, the bay's temperature excursions will be much less than if it were fully exposed on the Martian surface, allowing a reduction in the amount of thermal insulation and savings on mass. The MNL is well suited for delivering meteorological and atmospheric instruments to the Martian surface. The payload concept also enables the use of other environmental instruments. The small size and low mass of a MNL makes it ideally suited for piggy-backing on larger spacecraft. MNLs are designed primarily for use as surface networks but could also be used as pathfinders for high-value landed missions

Geochemical and numerical constraints on Neoarchean plate tectonics

This paper discusses early Neoarchean (2.8–2.7 Ga) plate tectonics by integrating knowledge from new geochemical observations and numerical models. Based on a geochemical dataset of 295 granitoid samples from the Karelian and Kola cratons of the Fennoscandian Shield, we divide Neoarchean juvenile (extracted from oceanic crust or mantle) granitoids into three groups: (1) low-HREE (heavy rare earth elements) TTGs (tonalite–trondhjemite–granodiorite) (high SiO2, lowMg, low-HREE, higher Sr, lower Ybn and higher Nb/Ta), (2) high-HREE TTGs (slightly lower range of SiO2, larger range of MgO contents and higher Cr and Ni contents, high-HREE, lower Sr, higher Ybn and lower Nb/Ta), and (3) high Ba–Sr sanukitoids (medium-HREE, high-Mg and high K–Ba–Sr). The main difference between the low- and high-HREE groups lies in their pressure-sensitive element contents, which indicates high-pressure melting conditions for the low-HREE group and low-pressure conditions for the high-HREE group. A possible tectonic scenario for the genesis of the two groups is an incipient hot subduction underneath a thick oceanic plateau/protocrust. Melting in the lower part of thick basaltic oceanic crust could produce TTGs of the low-HREE type, whereas low-pressure melting of subducting slab and possible interactions with the mantle wedge at shallow depths would be capable of generating high-HREE TTGs. The third group of Archean high Ba–Sr sanukitoidswas formed after the TTGs. Their lowSiO2 and high Mg–K–Ba–Sr contents suggest an origin by melting in an enriched (metasomatized) mantle source, probably as a result of a slab breakoff following a continental collision or attempted subduction of a thick oceanic plateau/TTG protocontinent. Such hypothesis is supported by numerical modeling results that suggest an increased occurrence of slab breakoff in the Archean, which locally increased temperatures within the mantle wedge. More frequent breakoff resulted, because subducting plates were weaker (due to rheologically thinner lithosphere and a thicker basaltic crust), and tensile stresses within the subducting plate were larger (due to a thick crust that transforms from buoyant basalt to dense eclogite)

Svecofennian intra-orogenic gabbroic magmatism: A case study from Turku, southwestern Finland

Using single-grain zircon U-Pb dating by LA-MC-ICPMS and whole-rock geochemistry, we have studied the Palaeoproterozoic gabbroic rocks from Moisio in southwest Finland. Three ages were obtained. The interpreted intrusion age is ~1.86 Ga, which places it in the 1.87–1.84 Ga intra-orogenic period of southern Svecofennia. The other ages, ~1.89 Ga and ~1.83 Ga, are inferred to be inherited and metamorphic ages, respectively. The K, LREE, LILE, Fe-, P-, Ti- and F-concentrations reveal two compositionally distinct groups: (i) an enriched monzogabbro group and (ii) a less enriched gabbro group. The composition of the monzogabbro group resembles the other intra-orogenic intrusions from southern Svecofennia, whereas the unrelated gabbro group is more comparable to the synorogenic rocks in the region. The magma source the monzogabbro experienced a subduction related carbonate metasomatism, induced by sediment subduction and subduction erosion. Evidently, the Moisio monzogabbro represent enriched, mantle derived magmatism in southern Svecofennia as a part of the intra-orogenic igneous activity. The intra-orogenic magmatism is considered to have conveyed considerable amounts of heat from the mantle into the crust contributing to subsequent lateorogenic high-grade metamorphism

Evidence of crustal growth during the Svecofennian orogeny : New isotopic data from the central parts of the Paleoproterozoic Central Finland Granitoid Complex

Peer reviewe

FLEX: fluorescence explorer

FLEX is a scientifically driven space mission to provide demonstration/validation of the instrumentation and technique for measuring the natural fluorescence of vegetation in the Fraunhofer lines. The payload consists of high spectral resolution (0.1-0.3 nm) CCD imaging grating spectrometer with two channels: one in the red (648-664 nm)and one in the blue (39 1- 438 nm) for working with several Fraunhofer lines. The across track FOV is 8.4°; ground spatial resolution is better than O.5x0.5km2. To increase the SIN ratio a steering mirror will be used, if necessary, to "freeze" the image and also to provide ca. 4° across track depointing. Calibration is made by viewing the sun via a diffuser plate switched into the telescope field of view. A separate CCD camera will allow cloud detection and scene identification. A TIR radiometer will provide simultaneous surface temperature measurements. The spacecraft, overall mass estimated at 200kg, is derived from the ASI-MITA bus which provides all the necessary subsystems and stabilized platform. By use of on-board storage, ground requirements for satellite control and data link are minimized; the possibility of local stations for real time reception/distribution is also envisaged. Provisional orbit characteristics are: LEO sun synchronous, 500-900km altitude. Priority will be given to highest revisit frequency on a sufficient number of selected test sites