Planetary surfaces

Abstract:

European Space Agency’s Mars Express (MEX) has been orbiting Mars for 20 years and its instruments have provided a plethora of observations of atmospheric dust and clouds. These observations have been analysed to produce many unique views of the processes leading to dust lifting and cloud formation, and a full picture of the climatologies of dust and clouds has emerged. Moreover, the orbit of MEX enables viewing the planet at many local times, giving a unique access to the diurnal variations of the atmosphere. This article provides an overview of the observations of dust and clouds on Mars by MEX, complemented by the Trace Gas Orbiter that has been accompanying MEX on orbit for some years.

Abstract:

Ultra-hot Jupiters (UHJs) are among the best targets for atmospheric characterization at high spectral resolution. Resolving their transmission spectra as a function of orbital phase offers a unique window into the 3D nature of these objects. In this work, we present three transits of the UHJ WASP-121b observed with Gemini-S/IGRINS. For the first time, we measure the phase-dependent absorption signals of CO and H2O in the atmosphere of an exoplanet, and we find that they are different. While the blueshift of CO increases during the transit, the absorption lines of H2O become less blueshifted with phase, and even show a redshift in the second half of the transit. These measurements reveal the distinct spatial distributions of both molecules across the atmospheres of UHJs. Also, we find that the H2O signal is absent in the first quarter of the transit, potentially hinting at cloud formation on the evening terminator of WASP-121b. To further interpret the absorption trails of CO and H2O, as well as the Doppler shifts of Fe previously measured with VLT/ESPRESSO, we compare the data to simulated transits of WASP-121b. To this end, we post-process the outputs of the global circulation models with a 3D Monte-Carlo radiative transfer code. Our analysis shows that the atmosphere of WASP-121b is subject to atmospheric drag, as previously suggested by small hotspot offsets inferred from phase-curve observations. Our study highlights the importance of phase-resolved spectroscopy in unravelling the complex atmospheric structure of UHJs and sets the stage for further investigations into their chemistry and dynamics.

Abstract:

Many upcoming lunar missions and payloads are targeting the south pole of the Moon, due to the volatiles potentially harboured in this region including ESA's PROSPECT instrument. PROSPECT is designed to sample the lunar regolith within the first meter of the surface and to analyse any volatiles found. Remote sensing methods and a range of datasets including thermal models, illumination models, LRO NAC images, LOLA DEMs and LRO NAC DEMs generated with shape-from-shading, were used to identify suitable areas for PROSPECT science within the south polar region (84–90°S). Sites identified were down selected using a science matrix and scoring sites of interest based on if and how well the point of interest met the science requirements of PROSPECT. The highest scoring sites are presented and proposed to be ideal candidate landing sites for missions targeting the lunar south polar region, especially for missions that are interested in sampling volatiles, micro cold traps and Permanently Shaded Regions (PSRs). Understanding and sampling these colder areas within the south polar region will advance the understanding of volatiles within the lunar surface and volatile transfer.