Venus has no seasons, slow rotation and a very massive atmosphere, which is mainly carbon dioxide with clouds primarily of sulphuric acid droplets. Infrared observations by previous missions to Venus revealed a bright 'dipole' feature surrounded by a cold 'collar' at its north pole. The polar dipole is a 'double-eye' feature at the centre of a vast vortex that rotates around the pole, and is possibly associated with rapid downwelling. The polar cold collar is a wide, shallow river of cold air that circulates around the polar vortex. One outstanding question has been whether the global circulation was symmetric, such that a dipole feature existed at the south pole. Here we report observations of Venus' south-polar region, where we have seen clouds with morphology much like those around the north pole, but rotating somewhat faster than the northern dipole. The vortex may extend down to the lower cloud layers that lie at about 50 km height and perhaps deeper. The spectroscopic properties of the clouds around the south pole are compatible with a sulphuric acid composition.

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Abstract. A novel simulation chamber, PASSxS (Planetary Atmosphere Simulation System for Spectroscopy), has been developed for absorption measurements performed with a Fourier transform spectrometer (FTS) and, possibly, a cavity ring-down (CRD) spectrometer with a sample temperature ranging from 100 up to 550 K, while the pressure of the gas can be varied from 10 mbar up to 60 bar. These temperature and pressure ranges cover a significant part of the planetary atmospheres in the solar system, and the absorption chamber can thus be used to simulate planetary atmospheres of solar planets and extrasolar planets with similar physical conditions. The optical absorption path for the FTS absorption measurements is 3.2 m due to the implementation of a multi-pass setup inside the chamber. The FTS measurements cover a wide spectral range, from the visible to the mid-infrared, with a sensitivity sufficient for medium-strength absorption bands. The FTS has been used previously to measure high-pressure atmospheres, including collision-induced absorption bands and continuum absorption at ambient temperatures. PASSxS allows the measurement of the temperature dependence of collision-induced bands and continuum absorption, which is important for both the modeling of planetary atmospheres and fundamental processes involving collisions between molecules and atoms.

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Thermogravimetry (TG) or Thermogravimetric Analysis (TGA) is a widely used technique to obtain information about thermal stability and composition and to monitor different thermal processes of materials. The TGA analysis is frequently used to monitor the deposition/sublimation and absorption/desorption processes of volatiles compounds in different environments: outgassing rates from degassing in space [1], dehydration and organics decomposition in minerals [2] and the fate of various materials in atmospheric environments [3]. In particular, it is possible to obtain a characterization of organic compounds by using Quartz Crystal Microbalance (QCM)-based sensors, equipped with an integrated heater in order to study the deposition and desorption processes. In this work, an organic compound (used as contaminant source) was characterized by using the breadboard of a QCM-based sensor, i.e. CAM (Contamination Assessment Microbalance), which shows several improvements compared to the previous Quartz Crystal Microbalance sensors used by European Space Agency (ESA) and National Aeronautics and Space Administration (NASA) [1,4]. CAM instrument aims to monitor contaminants and outgassing materials which are released by spacecrafts during in-orbit space missions characterizing the contaminant source by means of Thermogravimetric technique. The organic compound desorption rates and the enthalpy of sublimation (Î\u94Hsub) were retrieved by using the Langmuir relation while the sensor regeneration was obtained by means of thermal cycles by using the integrated heaters on crystal surface. The CAM breadboard validation, the experimental procedure and results are presented, and compared previous works