Extraterrestrial Mössbauer spectroscopy: more than 3 years of Mars exploration and developments for future missions

After almost 4 years of operating on the surface of Mars, Mössbauer spectroscopy has become a mature technique for robotic planetary exploration. The combination of quantitative information about the distribution of Fe among its oxidation and coordination states, identification of Fe-bearing phases, and relative distribution of Fe among those phases provides valuable contributions to the search for past water activity, the assessment of past environmental conditions, and the suitability for life of the two NASA Mars Exploration Rover landing sites. Experience from the Mars Exploration Rover Mission highlights needs for improvement of the instruments for future missions such as the Russian Phobos-Grunt and the European ExoMars rover.     

Observation of all-optical bump-on-tail instability

We demonstrate an all-optical bump-on-tail instability by considering the nonlinear interaction of two partially coherent spatial beams. For weak wave coupling, we observe momentum transfer with no variation in intensity. For strong wave coupling, modulations appear in intensity and evidence appears for wave (Langmuir) collapse at large scales. Borrowing plasma language, these limits represent regimes of weak and strong spatial optical turbulence. In both limits, the internal spectral energy redistribution is observed by recording and reconstructing a hologram of the evolving dynamics. The results are universal and can appear in any wave-kinetic system with short-wave-long-wave coupling.     

Uptake of silicone oil in the polystyrene matrix of the two phase system polystyrene/silicone oil as detected by NMR

The decrease of the droplet radii of silicone oil dispersed in a polystyrene matrix at a temperature of 140°C with increasing time was measured by NMR dynamic imaging. From this time dependence the diffusion coefficient of the silicone oil into the matrix was calculated to be 7 · 10⁻¹⁸ m² · s⁻¹. The uptake of the silicone oil in the polystyrene matrix was confirmed by broad line NMR measurements.