Modeling Noncondensing Compositional Convection for Applications to Super-Earth and Sub-Neptune Atmospheres
The Astrophysical Journal American Astronomical Society 961:1 (2024) 35
The Comet Interceptor Mission.
Space science reviews 220:1 (2024) 9
Abstract:
Here we describe the novel, multi-point Comet Interceptor mission. It is dedicated to the exploration of a little-processed long-period comet, possibly entering the inner Solar System for the first time, or to encounter an interstellar object originating at another star. The objectives of the mission are to address the following questions: What are the surface composition, shape, morphology, and structure of the target object? What is the composition of the gas and dust in the coma, its connection to the nucleus, and the nature of its interaction with the solar wind? The mission was proposed to the European Space Agency in 2018, and formally adopted by the agency in June 2022, for launch in 2029 together with the Ariel mission. Comet Interceptor will take advantage of the opportunity presented by ESA's F-Class call for fast, flexible, low-cost missions to which it was proposed. The call required a launch to a halo orbit around the Sun-Earth L2 point. The mission can take advantage of this placement to wait for the discovery of a suitable comet reachable with its minimum ΔV capability of 600 ms-1. Comet Interceptor will be unique in encountering and studying, at a nominal closest approach distance of 1000 km, a comet that represents a near-pristine sample of material from the formation of the Solar System. It will also add a capability that no previous cometary mission has had, which is to deploy two sub-probes - B1, provided by the Japanese space agency, JAXA, and B2 - that will follow different trajectories through the coma. While the main probe passes at a nominal 1000 km distance, probes B1 and B2 will follow different chords through the coma at distances of 850 km and 400 km, respectively. The result will be unique, simultaneous, spatially resolved information of the 3-dimensional properties of the target comet and its interaction with the space environment. We present the mission's science background leading to these objectives, as well as an overview of the scientific instruments, mission design, and schedule.Dynamics and clouds in planetary atmospheres from telescopic observations
Astronomy and Astrophysics Review Springer 31:1 (2023) 5
Abstract:
This review presents an insight into our current knowledge of the atmospheres of the planets Venus, Mars, Jupiter, Saturn, Uranus and Neptune, the satellite Titan, and those of exoplanets. It deals with the thermal structure, aerosol properties (hazes and clouds, dust in the case of Mars), chemical composition, global winds, and selected dynamical phenomena in these objects. Our understanding of atmospheres is greatly benefitting from the discovery in the last 3 decades of thousands of exoplanets. The exoplanet properties span a broad range of conditions, and it is fair to expect as much variety for their atmospheres. This complexity is driving unprecedented investigations of the atmospheres, where those of the solar systems bodies are the obvious reference. We are witnessing a significant transfer of knowledge in both directions between the investigations dedicated to Solar System and exoplanet atmospheres, and there are reasons to think that this exchange will intensity in the future. We identify and select a list of research subjects that can be conducted at optical and infrared wavelengths with future and currently available ground-based and space-based telescopes, but excluding those from the space missions to solar system bodies.Latitudinal variations in methane abundance, aerosol opacity and aerosol scattering efficiency in Neptune's atmosphere determined from VLT/MUSE
Journal of Geophysical Research: Planets American Geophysical Union 128:11 (2023) e2023JE007980
Abstract:
Spectral observations of Neptune made in 2019 with the MUSE instrument at the Very Large Telescope in Chile have been analysed to determine the spatial variation of aerosol scattering properties and methane abundance in Neptune’s atmosphere. The darkening of the South Polar Wave (SPW) at ∼ 60◦S, and dark spots such as the Voyager 2 Great Dark Spot is concluded to be due to a spectrally-dependent darkening (λ < 650nm) of particles in a deep aerosol layer at ∼ 5 bar and presumed to be composed of a mixture of ~ 650 nm, with bright zones latitudinally separated by ∼ 25◦ . This feature, similar to the spectral characteristics of a discrete deep bright spot DBS-2019 found in our data, is found to be consistent with a brightening of the particles in the same ∼5-bar aerosol layer at λ > 650 nm. We find the properties of an overlying methane/haze aerosol layer at ∼ 2 bar are, to first-order, invariant with latitude, while variations in the opacity of an upper tropospheric haze layer reproduce the observed reflectivity at methane-absorbing wavelengths, with higher abundances found at the equator and also in a narrow ‘zone’ at 80◦S. Finally, we find the mean abundance of methane below its condensation level to be 6-7% at the equator reducing to ∼3% south of ∼25◦S, although the absolute abundances are model dependent.Latitudinal variations in methane abundance, aerosol opacity and aerosol scattering efficiency in Neptune's atmosphere determined from VLT/MUSE
(2023)