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JAXA's upcoming MMX (Martian Moons eXploration) mission will deliver a small rover to Phobos, to explore its surface complementary to the MMX orbiter and the sample return lander. On board this rover is a Raman spectrometer, the RAX Instrument (RAman Spectrometer for MMX), a payload to science. RAX has been designed for being capable to analyze the mineral composition of the Phobos' surface, in order to help reveal the nature and distribution of materials on the surface and ultimately the origin and evolution of the moon. Attached to MMX spacecraft, with direct view from the RAX instrument, a polyethylene terephthalate (PET) target will be placed for on‐ground and during cruise, spectral instrument performances verification, before the MMX rover is released and dropped to the Phobos surface for developing its scientific tasks. A novel deuterated PET material was proposed as verification target (VT) to check the spectral instrument performances. INTA‐CAB developed, manufactured and qualified for the MMX‐RAX space mission, 13 mm diameter and 2‐mm thick pellets of this material, which incorporates two relevant improvement characteristics: reduction in fluorescence and additional Raman bands with regard to ordinary PET used with this purpose. The material was selected as RAX VT and delivered to DLR for performance tests and later integration into the MMX rover together with the RAX flight model. The RAX VT will be critical to check the instrument performances during the several months cruise phase after launch and just before its landing on Phobos surface. This paper reports the development and characterization of the deuterated PET. [ABSTRACT FROM AUTHOR]

The study of uranium oxides at different conditions is of paramount importance in the nuclear field, especially regarding characterization of the spent nuclear fuel behavior in dry storage scenarios. This paper reports results of XRD and Raman analysis on four powdered samples prepared in order to cover a specific stoichiometry range in UO2+x, i.e. x = 0.24, 0.26, 0.28 and 0.30. XRD results reveal a clear increase of the average tetragonal distortion with the increase in oxidation degree, with the main phase detected for all the samples being a weakly tetragonal phase identified as U3O7−z (c/a ≪ 1.032). U4O9 has not been detected in any sample. The Raman study carried out consists of both qualitative and quantitative analysis. The former, where a profile analysis has been performed on the acquired spectra, shows that the most intense bands (centered at ∼455 and ∼635 cm−1) are actually a doublet each, in agreement with a previous experimental study. Moreover, this work shows, for the first time, that the band at ∼160 cm−1 is also a doublet, which makes its classical assignment no longer obvious. The most important and original results from this study are obtained by applying Quantitative Raman Spectroscopy (QRS). This analysis shows that the second contribution at ∼475 cm−1 to the known T2g mode increases its relative intensity with the oxidation degree. This contribution may be related to the tetragonal distortion occurring in the cubic UO2 lattice due to the addition of interstitial oxygen, based on its comparison with the obtained XRD outcomes. In addition, the so-called "defects band" (centered at around 600 cm−1) presents a remarkable kink, of around 20 cm−1, in its Raman shift between UO2.26 and UO2.28. Such behavior might be directly associated with the observed appearance of the stoichiometric U3O7 phase (c/a = 1.032) for UO2.28 and UO2.30. [ABSTRACT FROM AUTHOR]

In this work, we studied the dehydration process of the glycine‐MgSO4·5H2O complex under Mars‐relevant conditions (99% CO2 and 0.6% H2O under ultra violet (UV) irradiation exposure at 7‐mbar pressure and high vacuum conditions: 8 × 10−5 and 5 × 10−5 mbar) by in situ Raman spectroscopy inside a planetary atmosphere and surface chamber (PASC). This work provides quality Raman spectra taken under simulated planetary conditions (to be integrated in a database), as Raman spectroscopy forms part of the current and upcoming NASA and ESA Mars planetary missions. The results demonstrate that Raman spectroscopy can be used to calculate rates of dehydration of the glycine‐MgSO4·5H2O compound to study the chemical stability with respect to photodecomposition (1) of metal‐bound glycine molecules forming the complex and (2) glycine expelled from the complex, both under Mars‐simulated conditions; finally, Raman spectroscopy can also be used to quantify intermolecular interactions in terms of local pressures. Importantly, advanced detection of water molecules as part of a complex with astrobiological interest under planetary conditions plays a crucial role in planetary missions. [ABSTRACT FROM AUTHOR]

The dynamics of the liquid-air interface of aqueous solutions of a tensioactive triblock copolymer is studied using surface quasielastic light scattering over a broad range of concentrations and temperatures. The results show that the classical theoretical spectrum for monolayers on a Newtonian fluid can be applied only for concentrations below 4.10(super -2).

Water ice, hydrated salts, and other volatile ices such as carbon dioxide (CO2), have been detected by spectroscopy on Europa’s surface. Although the presence of other candidate compounds like clathrate hydrates have not yet been observed on the moon, the existence of water and carbon dioxide combined with low temperature and relatively high cryostatic pressure in the interior of the planetary body, favors their occurrence. In this study, the evolution of the H2O–MgSO4–CO2 system as a function of temperature, pressure and high salt concentration was investigated, focusing especially on the differences between the resulting mineral parageneses. CO2-clathrate formation and dissociation were examined by Raman spectroscopy in the presence of other hydrated phases crystallized from aqueous solutions rich in magnesium sulfate (MgSO4) at several concentrations (5, 17 and 30wt%) from 268 to 290K and pressures up to 60bar. The CO2-clathrate experimental equilibrium line in this salty system is presented for both gas and liquid CO2 stability fields. During the heating process, the mineral assemblage of the system evolved differently depending on the salt concentration. At subsaturation (5wt% of MgSO4), the CO2-clathrate co-existed with water ice from 268 to 272K. However, when the initial sulfate concentration was 17wt%, at a temperature above 269K, no mineral phase was stable apart from CO2-clathrate. If the salt concentration of the system was supersaturated (30wt%), CO2-clathrate co-existed with meriadianiite (MgSO4·11H2O) from 269 to 275K. Subsequently, meridianiite was transformed into epsomite (MgSO4·7H2O) and continued crystallizing until 300K. The evolution of the supersaturated solution at different heating rates was also evaluated in detail. In experiments with the fastest heating, the epsomite was not stabilized and the resulting aqueous solution became more concentrated than initially, promoting a clathrate dissociation at lower temperatures than expected. Volume changes due to mineral transformations and partial/total melting processes were assessed for the system and applied to Europa’s geology. Thus, assuming that this system is present in Europa’s interior, the evolution of the presumed fluids and mineral assemblages may have resulted in the generation of local stresses promoting resurfacing. Depending on the initial composition of the system, the percentage of volume change would imply a chaotic terrain formation, or cause faulting. [ABSTRACT FROM AUTHOR]

The study of uranium oxides at different conditions is of paramount importance in the nuclear field, especially regarding characterization of the spent nuclear fuel behavior in dry storage scenarios. This paper reports results of XRD and Raman analysis on four powdered samples prepared in order to cover a specific stoichiometry range in UO 2+ x , i.e. x = 0.24, 0.26, 0.28 and 0.30. XRD results reveal a clear increase of the average tetragonal distortion with the increase in oxidation degree, with the main phase detected for all the samples being a weakly tetragonal phase identified as U 3 O 7- z ( c / a ≪ 1.032). U 4 O 9 has not been detected in any sample. The Raman study carried out consists of both qualitative and quantitative analysis. The former, where a profile analysis has been performed on the acquired spectra, shows that the most intense bands (centered at ∼455 and ∼635 cm -1 ) are actually a doublet each, in agreement with a previous experimental study. Moreover, this work shows, for the first time, that the band at ∼160 cm -1 is also a doublet, which makes its classical assignment no longer obvious. The most important and original results from this study are obtained by applying Quantitative Raman Spectroscopy (QRS). This analysis shows that the second contribution at ∼475 cm -1 to the known T 2g mode increases its relative intensity with the oxidation degree. This contribution may be related to the tetragonal distortion occurring in the cubic UO 2 lattice due to the addition of interstitial oxygen, based on its comparison with the obtained XRD outcomes. In addition, the so-called "defects band" (centered at around 600 cm -1 ) presents a remarkable kink, of around 20 cm -1 , in its Raman shift between UO 2.26 and UO 2.28 . Such behavior might be directly associated with the observed appearance of the stoichiometric U 3 O 7 phase ( c / a = 1.032) for UO 2.28 and UO 2.30 .

Identification of spectroscopic fingerprints that correspond to relevant molecules/minerals in a Mars-like environment is a crucial search in astrobiology. Therefore, we studied the stability of Gly·MgSO 4 ·5H 2 O under Mars-like surface conditions and compared it to the behavior of epsomite and glycine. Gly·MgSO 4 ·5H 2 O has been identified as a molecule of astrobiological interest since an amino acid and water molecules, which are essential for life, are part of its structure. Furthermore, this compound may form by the interaction of sulfate minerals with glycine-bearing aqueous solutions, and both could be present on Mars. The main analyses were performed by using in situ Raman spectroscopy, a ground-breaking technique for NASA and ESA Mars planetary missions. We have integrated a Raman spectrometer in a Planetary Atmosphere and Surfaces Chamber (PASC) and have identified the processing of molecules exposed to a simulated martian atmosphere, UV irradiation, and temperature. Our results show that pressure is critical to provoke amorphization of Gly·MgSO 4 ·5H 2 O, and the release of glycine from the compound; the stabilization effect at low temperature and stability of Gly·MgSO 4 ·5H 2 O is greater than to glycine and epsomite. The strategy employed here allows us to evaluate the effect of diverse simulated martian environmental conditions on molecular preservation by using Raman spectroscopy.