Raman spectra of olivine measured in different planetary environments

Missions to bodies of our solar system are coming up and imply new instrumentation to be applied remotely and in situ. In ESA’s ExoMars mission the Raman Laser Spectrometer (RLS) will identify minerals and organic compounds in Martian surface rocks and soils. Here we present the results of a Raman study of different olivines with variable Fo and Fa contents. We chose olivine because it is a rock forming mineral and is found as an abundant mineral in Martian meteorites. We determined the Raman spectra in different environmental conditions that include vacuum, 8 mbar CO2 atmosphere and temperatures between room temperature and 10 K. These environmental conditions resemble those on asteroids as well as on Mars and Moon. Thus our study investigates the influence of these varying conditions on the position and band width of the Raman lines, which is to be known when such investigations are performed in future space missions

Optimization of Interplanetary Rendezvous Trajectories for Solar Sailcraft Using a Neurocontroller

As for all low-thrust spacecraft, finding optimal solar sailcraft trajectories is a difficult and time-consuming task that involves a lot of experience and expert knowledge, since the convergence behavior of optimizers that are based on numerical optimal control methods depends strongly on an adequate initial guess, which is often hard to find. Even if the op-timizer converges to an ”optimal trajectory”, this trajectory is typically close to the initial guess that is rarely close to the global optimum. This paper demonstrates, that artificial neural networks in combination with evolutionary algorithms can be applied successfully for optimal solar sailcraft steering. Since these evolutionary neurocontrollers explore the trajectory search space more exhaustively than a human expert can do by using tradi-tional optimal control methods, they are able to find steering strategies that generate better trajectories, which are closer to the global optimum. Results are presented for a Near Earth Asteroid rendezvous mission and for a Mercury rendezvous mission

Lunar Exploration Orbiter (LEO): Providing a Globally Covered, Highly Resolved, Integrated Geological, Geochemical and Gephysical Data Base of the Moon

The German initiative for the Lunar Exploration Orbiter (LEO) originated from the national conference “Exploration of our Solar System”, held in Dresden in November 2006. Major result of this conference was that the Moon is of high interest for the scientific community for various reasons, it is affordable to perform an orbiting mission to Moon and it insures technological and scientific progress necessary to assist further exploration activities of our Solar System. Based on scientific proposals elaborated by 50 German scientists in January 2007, a preliminary payload of 12 instruments was defined. Further analysis were initated by DLR in the frame of two industry contracts, to perform a phase-zero mission definition. The Moon, our next neighbour in the Solar System is the first choice to learn, how to work and live without the chance of immediate support from earth and to get prepared for further and farther exploration missions. We have to improve our scientific knowledge base with respect to the Moon applying modern and state of the art research tools and methods. LEO is planed to be launched in 2012 and shall orbit the Moon for about four years in a low altitude orbit

The composition of the protosolar disk and the formation conditions for comets

Conditions in the protosolar nebula have left their mark in the composition of cometary volatiles, thought to be some of the most pristine material in the solar system. Cometary compositions represent the end point of processing that began in the parent molecular cloud core and continued through the collapse of that core to form the protosun and the solar nebula, and finally during the evolution of the solar nebula itself as the cometary bodies were accreting. Disentangling the effects of the various epochs on the final composition of a comet is complicated. But comets are not the only source of information about the solar nebula. Protostellar disks around young stars similar to the protosun provide a way of investigating the evolution of disks similar to the solar nebula while they are in the process of evolving to form their own solar systems. In this way we can learn about the physical and chemical conditions under which comets formed, and about the types of dynamical processing that shaped the solar system we see today. This paper summarizes some recent contributions to our understanding of both cometary volatiles and the composition, structure and evolution of protostellar disks.Comment: To appear in Space Science Reviews. The final publication is available at Springer via http://dx.doi.org/10.1007/s11214-015-0167-

On the origin and evolution of the material in 67P/Churyumov-Gerasimenko

International audiencePrimitive objects like comets hold important information on the material that formed our solar system. Several comets have been visited by spacecraft and many more have been observed through Earth- and space-based telescopes. Still our understanding remains limited. Molecular abundances in comets have been shown to be similar to interstellar ices and thus indicate that common processes and conditions were involved in their formation. The samples returned by the Stardust mission to comet Wild 2 showed that the bulk refractory material was processed by high temperatures in the vicinity of the early sun. The recent Rosetta mission acquired a wealth of new data on the composition of comet 67P/Churyumov-Gerasimenko (hereafter 67P/C-G) and complemented earlier observations of other comets. The isotopic, elemental, and molecular abundances of the volatile, semi-volatile, and refractory phases brought many new insights into the origin and processing of the incorporated material. The emerging picture after Rosetta is that at least part of the volatile material was formed before the solar system and that cometary nuclei agglomerated over a wide range of heliocentric distances, different from where they are found today. Deviations from bulk solar system abundances indicate that the material was not fully homogenized at the location of comet formation, despite the radial mixing implied by the Stardust results. Post-formation evolution of the material might play an important role, which further complicates the picture. This paper discusses these major findings of the Rosetta mission with respect to the origin of the material and puts them in the context of what we know from other comets and solar system objects

A late Cretaceous 40Ar-39Ar age for the Lappajarvi impact crater, Finland

We report on a 40Ar — 39Ar study of karnaite from the ⁓ 17 km Lappajarvi impact crater, Finland. Four samples from a 3,000 m profile across the crater center give rather well defined age plateaux and indicate complete degassing at the time of the impact event. The mean age is 77 m.y., much younger than geologically derived age estimates.           ARK: https://n2t.net/ark:/88439/y062490 Permalink: https://geophysicsjournal.com/article/186 &nbsp

LIBS studies of ferric salts in frozen solutions under Martian conditions

Laser-induced breakdown spectroscopy (LIBS) is a promising analytical tool for the geochemical investigation of surfaces and soil in particular for extraterrestrial exploration. With the ChemCam instrument on the NASA Mars Science Laboratory (MSL), which will arrive on Mars in summer 2012, the LIBS technique will be applied for in-situ analysis on a planetary mission for the first time. Additionally other missions with LIBS are proposed for instance for Venus or the Moon. To optimize the scientific return with LIBS, i.e. to most precisely obtain the elemental composition of rock, soil and possibly frozen samples with LIBS, qualitative and quantitative methods for data analysis have been developed and improved by a number of studies. One valuable attempt to compensate for matrix effects and other factors that influence the plasma’s composition and properties and therefore the LIBS spectra are multivariate analysis (MVA) methods. This study investigates the potential of LIBS for dentifying ferric salts (FeCl3 and Fe2(SO4)3) when pressed into pellets and in frozen salt solutions utilizing partial least squares discriminant analysis (PLS-DA). Ferric salts are considered in the context of possibly existing liquid brines on Mars and are moreover of particular interest for (astro-) biology in view of possible extraterrestrial life since iron is an essential component of life as we know it. Ferric sulfates have been found on Mars at various locations such as jarosite in Meridiani Planum and in soils in Gusev Crater. Chloride bearing salts were also identified in deposits on the southern hemisphere. On Mars these salts could also appear in form of frozen salt solutions which can be investigated using the LIBS technique as shown previously