Cassini INMS constraints on the composition and latitudinal fractionation of Saturn ring rain material

Miller, Kelly E.; Waite, J. H.; Perryman, R.; Perry, M. E.; Bouquet, Alexis; Magee, B.; Bolton, B.; Brockwell, T.; Hedman, M. M.; Glein, Christopher R.

doi:10.1016/j.icarus.2019.113595

Cited by 24 publications

(93 citation statements)

References 47 publications

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“…The profiles presented here provide further evidence from INMS for an external source providing Saturn's upper atmosphere with a variety of unexpected species, as previously reported in Miller et al. (2020), Perry et al. (2018), Waite et al.…”

Section: Resultssupporting

confidence: 87%

“…They also report that the H 2 profile derived from INMS before and after closest approach suggests that effects from the spacecraft's speed are negligible in close proximity to the planet. Other recent studies also find no significant effects on the measurements from the spacecraft's high speed (Miller et al., 2020; Perry et al., 2018; Yelle et al., 2018), and our analysis thus far shows no evidence of issues stemming from the spacecraft's speed.…”

Section: Methodssupporting

confidence: 65%

“…(2018) and Miller et al. (2020) analyzed a larger portion of the instrument's mass range, confirming the existence of heavy neutral hydrocarbons infalling from the rings into the atmosphere and attributing the influx to certain regions of the D ring. Waite et al.…”

Section: Introductionmentioning

confidence: 84%

“…They reported the distributions of H 2 , He, and CH 4 in Saturn's equatorial thermosphere, noting that the density profiles of H 2 and He are consistent with an atmosphere in diffusive equilibrium, but that the higher than expected amounts of CH 4 in this region of the atmosphere can only be attributed to an external source with a flux of approximately 1.2× 10 13 m −2 s −1 . Waite et al (2018) and Miller et al (2020) analyzed a larger portion of the instrument's mass range, confirming the existence of heavy neutral hydrocarbons infalling from the rings into the atmosphere and attributing the influx to certain regions of the D ring. Waite et al (2018) and Perry et al (2018) both concluded that at least 10 4 kg/s of endogenous material was being deposited into Saturn's upper atmosphere from the rings during these observations.…”

Section: Introductionmentioning

confidence: 84%

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Compositional Measurements of Saturn's Upper Atmosphere and Rings from Cassini INMS

Serigano

Hörst

et al. 2020

JGR Planets

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The Cassini spacecraft's last orbits directly sampled Saturn's thermosphere and revealed a much more chemically complex environment than previously believed. Observations from the Ion and Neutral Mass Spectrometer (INMS) aboard Cassini provided compositional measurements of this region and found an influx of material raining into Saturn's upper atmosphere from the rings. We present here an in‐depth analysis of the CH4, H2O, and NH3 signal from INMS and provide further evidence of external material entering Saturn's atmosphere from the rings. We use a new mass spectral deconvolution algorithm to determine the amount of each species observed in the spectrum and use these values to determine the influx and mass deposition rate for these species.

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Section: Resultssupporting

confidence: 87%

Section: Methodssupporting

confidence: 65%

Section: Introductionmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 84%

See 2 more Smart Citations

Compositional Measurements of Saturn's Upper Atmosphere and Rings from Cassini INMS

Serigano

Hörst

et al. 2020

JGR Planets

View full text Add to dashboard Cite

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“…During the Cassini spacecraft's end-of-mission proximal orbits, mass fluxes into Saturn's atmosphere of up to 20 × 10 4 kg s −1 were derived from in situ measurements of infalling ring material [52,53,69,70], leading to significant modification of its equatorial ionosphere [11,71,72]. Cassini Ion and Neutral Mass Spectrometer spectra in Saturn's upper atmosphere were unexpectedly rich [52], showing stable signal out to 100 mass per charge (u), with a strong 28u peak containing significant CO contribution [73]. Neptune's rings are of course less massive than Saturn's, but the implicated source at Saturn was the tenuous D68 ringlet [52].…”

Section: (C) Discussion Of External Influxmentioning

confidence: 99%

Atmospheric implications of the lack of H ₃ ⁺ detection at Neptune

Moore

Moses

Melin

et al. 2020

Phil. Trans. R. Soc. A.

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H 3 + has been detected at all of the solar system giant planets aside from Neptune. Current observational upper limits imply that there is far less H 3 + emission at Neptune than rudimentary modelling would suggest. Here, we explore via modelling a range of atmospheric conditions in order to find some that could be consistent with observational constraints. In particular, we consider that the upper atmosphere might be much cooler than it was during the 1989 Voyager 2 encounter, and we examine the impact of an enhanced influx of external material that could act to reduce H 3 + density. Resulting ionosphere models that are consistent with existing H 3 + observational constraints have an exospheric temperature of 450 K or less, 300 K lower than the Voyager 2 value. Alternatively, if a topside CO influx of 2 × 10 8 cm −2 s −1 is imposed, the upper atmospheric temperature can be higher, up to 550 K. The potential cooling of Neptune’s atmosphere is relevant for poorly understood giant planet thermospheric energetics, and would also impact aerobreaking manoeuvers for any future spacecraft. Such a large CO influx, if present, could imply Triton is a very active moon with prominent atmospheric escape, and/or that Neptune’s rings significantly modify its upper atmosphere, and the introduction of so much exogenic material would complicate interpretation of the origin of species observed in Neptune’s lower atmosphere. This article is part a discussion meeting issue ‘Future exploration of ice giant systems’.

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Cassini Exploration of the Planet Saturn: A Comprehensive Review

Ingersoll

2020

Space Sci Rev

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Before Cassini, scientists viewed Saturn’s unique features only from Earth and from three spacecraft flying by. During more than a decade orbiting the gas giant, Cassini studied the planet from its interior to the top of the atmosphere. It observed the changing seasons, provided up-close observations of Saturn’s exotic storms and jet streams, and heard Saturn’s lightning, which cannot be detected from Earth. During the Grand Finale orbits, it dove through the gap between the planet and its rings and gathered valuable data on Saturn’s interior structure and rotation. Key discoveries and events include: watching the eruption of a planet-encircling storm, which is a 20- or 30-year event, detection of gravity perturbations from winds 9000 km below the tops of the clouds, demonstration that eddies are supplying energy to the zonal jets, which are remarkably steady over the 25-year interval since the Voyager encounters, re-discovery of the north polar hexagon after 25 years, determination of elemental abundance ratios He/H, C/H, N/H, P/H, and As/H, which are clues to planet formation and evolution, characterization of the semiannual oscillation of the equatorial stratosphere, documentation of the mysteriously high temperatures of the thermosphere outside the auroral zone, and seeing the strange intermittency of lightning, which typically ceases to exist on the planet between outbursts every 1–2 years. These results and results from the Jupiter flyby are all discussed in this review.

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Cassini INMS constraints on the composition and latitudinal fractionation of Saturn ring rain material

Cited by 24 publications

References 47 publications

Compositional Measurements of Saturn's Upper Atmosphere and Rings from Cassini INMS

Compositional Measurements of Saturn's Upper Atmosphere and Rings from Cassini INMS

Atmospheric implications of the lack of H ₃ ⁺ detection at Neptune

Cassini Exploration of the Planet Saturn: A Comprehensive Review

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Cassini INMS constraints on the composition and latitudinal fractionation of Saturn ring rain material

Cited by 24 publications

References 47 publications

Compositional Measurements of Saturn's Upper Atmosphere and Rings from Cassini INMS

Compositional Measurements of Saturn's Upper Atmosphere and Rings from Cassini INMS

Atmospheric implications of the lack of H 3 + detection at Neptune

Cassini Exploration of the Planet Saturn: A Comprehensive Review

Contact Info

Product

Resources

About

Atmospheric implications of the lack of H ₃ ⁺ detection at Neptune