The Hera Saturn entry probe mission

Mousis, O.; Atkinson, D. H.; Spilker, Thomas R.; Venkatapathy, Ethiraj; Poncy, J.; Frampton, Robert; Coustenis, A.; Reh, Kim; Lebreton, Jean‐Pierre; Fletcher, Leigh N.; Hueso, R.; Amato, M.; Colaprete, A.; Ferri, F.; Stam, Daphné; Würz, Peter; Atreya, S. K.; Aslam, Shahid; Banfield, D.; Calcutt, S. B.; Fischer, G.; Holland, Andrew D.; Keller, Christoph U.; Kessler, E.; Leese, M. R.; Levacher, P.; Morse, A. D.; Muñoz, Olga; Renard, Jean‐Baptiste; Sheridan, S.; Schmider, F. X.; Snik, Frans; Waite, J. H.; Bird, M. K.; Cavalié, T.; Deleuil, M.; Fortney, Jonathan J.; Gautier, D.; Guillot, T.; Lunine, Jonathan I.; Marty, Bernard; Nixon, C. A.; Orton, Glenn S.; Sánchez‐Lavega, A.

doi:10.1016/j.pss.2015.06.020

Cited by 29 publications

(14 citation statements)

References 48 publications

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“…Saturn_H2O_map_observations A&A proofs: manuscript no. Saturn_H2O_map_observations as well as possibly direct in situ measurements (Mousis et al 2014(Mousis et al , 2016(Mousis et al , 2018, will also help to improve our understanding of the outstanding and more general question of the origin of exogenic species in giant planet atmospheres.…”

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confidence: 99%

Herschel map of Saturn’s stratospheric water, delivered by the plumes of Enceladus

Cavalié

Hue

Hartogh

et al. 2019

A&A

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Context. The origin of water in the stratospheres of Giant Planets has been an outstanding question ever since its first detection by ISO some 20 years ago. Water can originate from interplanetary dust particles, icy rings and satellites and large comet impacts. Analysis of Herschel Space Observatory observations have proven that the bulk of Jupiter's stratospheric water was delivered by the Shoemaker-Levy 9 impacts in 1994. In 2006, the Cassini mission detected water plumes at the South Pole of Enceladus, placing the moon as a serious candidate for Saturn's stratospheric water. Further evidence was found in 2011, when Herschel demonstrated the presence of a water torus at the orbital distance of Enceladus, fed by the moon's plumes. Finally, water falling from the rings onto Saturn's uppermost atmospheric layers at low latitudes was detected during the final orbits of Cassini's end-of-mission plunge into the atmosphere. Aims. In this paper, we use Herschel mapping observations of water in Saturn's stratosphere to identify its source. Methods. Several empirical models are tested against the Herschel-HIFI and -PACS observations, which were collected on December 30, 2010, and January 2 nd , 2011 (respectively). Results. We demonstrate that Saturn's stratospheric water is not uniformly mixed as a function of latitude, but peaking at the equator and decreasing poleward with a Gaussian distribution. We obtain our best fit with an equatorial mole fraction 1.1 ppb and a half-width at half-maximum of 25˝, when accounting for a temperature increase in the two warm stratospheric vortices produced by Saturn's Great Storm of 2010-2011. Conclusions. This work demonstrates that Enceladus is the main source of Saturn's stratospheric water.

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confidence: 99%

Herschel map of Saturn’s stratospheric water, delivered by the plumes of Enceladus

Cavalié

Hue

Hartogh

et al. 2019

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“…Alongside the Ice Giant proposals, European scientists are developing the science case for in situ exploration of Saturn's atmosphere as a logical successor to Cassini's orbital exploration of Saturn (Mousis et al 2014). The Hera Saturn probe mission was proposed to ESA's M4 and M5 competitions (Mousis et al 2016) but recognized that an international partnership would be needed to provide the carrier spacecraft to Saturn, and the thermal protection system and aeroshell.…”

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confidence: 99%

A Review of the in Situ Probe Designs from Recent Ice Giant Mission Concept Studies

et al. 2020

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For the Ice Giants, atmospheric entry probes provide critical measurements not attainable via remote observations. Including the 2013-2022 NASA Planetary Decadal Survey, there have been at least five comprehensive atmospheric probe engineering design studies performed in recent years by NASA and ESA. International science definition teams have assessed the science requirements, and each recommended similar measurements and payloads to meet science goals with current instrument technology. The probe system concept has matured and converged on general design parameters that indicate the probe would include a 1-meter class aeroshell and have a mass around 350 to 400-kg. Probe battery sizes vary, depending on the duration of a post-release coast phase, and assumptions about heaters and instrument power needs. The various mission concepts demonstrate the need for advanced power and thermal protection system development. The many completed studies

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“…For these latters, the recent Juno/MWR data (Bolton et al 2017), presenting an unexpected NH 3 distribution below the condensation level, prove that robust 3D models accounting for chemistry and dy-namics are highly needed to decipher their composition. These 3D models of the tropospheres of the solar system giant planets will be crucial to help select the latitude of any future entry probe (Arridge et al 2014;Mousis et al 2014Mousis et al , 2016Mousis et al , 2018.…”

Section: Species Uranusmentioning

confidence: 99%

Reduced chemical scheme for modelling warm to hot hydrogen-dominated atmospheres

Venot

Bounaceur

Dobrijévic

et al. 2019

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Context. Three dimensional models that account for chemistry are useful tools to predict the chemical composition of (exo)planet and brown dwarf atmospheres and interpret observations of future telescopes, such as JWST and ARIEL. Recent Juno observations of the NH 3 tropospheric distribution in Jupiter (Bolton et al. 2017) also indicate that 3D chemical modelling may be necessary to constrain the deep composition of the giant planets of the Solar System. However, due to the high computational cost of chemistry calculations, 3D chemical modelling has so far been limited. Aims. Our goal is to develop a reduced chemical scheme from the full chemical scheme of Venot et al. (2012) able to reproduce accurately the vertical profiles of the observable species (H 2 O, CH 4 , CO, CO 2 , NH 3 , and HCN). This reduced scheme should have a size compatible with three dimensional models and be usable across a large parameter space (e.g. temperature, pressure, elemental abundance). The absence of C 2 H 2 from our reduced chemical scheme prevents its use to study hot C-rich atmospheres. Methods. We use a mechanism-processing utility designed for use with Chemkin-Pro to reduce a full detailed mechanism. ANSYS Chemkin-Pro Reaction Workbench allows the reduction of a reaction mechanism for a given list of target species and a specified level of accuracy. We take a warm giant exoplanet with solar abundances, GJ 436b, as a template to perform the scheme reduction. To assess the validity of our reduced scheme, we take the uncertainties on the reaction rates into account in Monte-Carlo runs with the full scheme, and compare the resulting vertical profiles with the reduced scheme. We explore the range of validity of the reduced scheme even further by applying our new reduced scheme to GJ 436b's atmosphere with different elemental abundances, to three other exoplanet atmospheres (GJ 1214b, HD 209458b, HD 189733b), a brown dwarf atmosphere (SD 1110), and to the troposphere of two giant planets of the Solar System (Uranus and Neptune). Results. For all cases except one, the abundances predicted by the reduced scheme remain within the error bars of the model with the full scheme. Expectedly, we found important differences that cannot be neglected only for the C-rich hot atmosphere. The reduced chemical scheme allows more rapid runs than the full scheme it derived from (∼30 times faster). Conclusions. We have developed a reduced scheme containing 30 species and 181 reversible reactions. This scheme has a large range of validity and can be used to study all kind of warm atmospheres, except hot C-rich ones, which contains a high amount of C 2 H 2 . It can be used in 1D models, for fast computations, but also in 3D models for hot giant (exo)planet and brown dwarf atmospheres.

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The Hera Saturn entry probe mission

Cited by 29 publications

References 48 publications

Herschel map of Saturn’s stratospheric water, delivered by the plumes of Enceladus

Herschel map of Saturn’s stratospheric water, delivered by the plumes of Enceladus

A Review of the in Situ Probe Designs from Recent Ice Giant Mission Concept Studies

Reduced chemical scheme for modelling warm to hot hydrogen-dominated atmospheres

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