Chemical and Isotopic Composition Measurements on Atmospheric Probes Exploring Uranus and Neptune

By Keith Cowing
Status Report
June 19, 2023
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Chemical and Isotopic Composition Measurements on Atmospheric Probes Exploring Uranus and Neptune
Proposed descent probe mass spectrometer experiment, with four major functional units indicated by color: the time-of-flight mass spectrometer (TOF-MS; blue), the gas separation and enrichment system (green), the reference gas system (red), and the tunable laser spectrometer (yellow). The abbreviations are as follows: valves (V), regulating valves (RV), pressure gauges (G), heater (H), conductance limiters (C), pumps (P), gas reservoirs (RG), and non-evaporative getter (NEG). — astro-ph.EP

So far no designated mission to either of the two ice giants, Uranus and Neptune, exists. Almost all of our gathered information on these planets comes from remote sensing.

In recent years, NASA and ESA have started planning for future mission to Uranus and Neptune, with both agencies focusing their attention on orbiters and atmospheric probes. Whereas information provided by remote sensing is undoubtedly highly valuable, remote sensing of planetary atmospheres also presents some shortcomings, most of which can be overcome by mass spectrometers.

In most studies presented to date a mass spectrometer experiment is thus a favored science instrument for in situ composition measurements on an atmospheric probe. Mass spectrometric measurements can provide unique scientific data, i.e., sensitive and quantitative measurements of the chemical composition of the atmosphere, including isotopic, elemental, and molecular abundances.

In this review paper we present the technical aspects of mass spectrometry relevant to atmospheric probes. This includes the individual components that make up mass spectrometers and possible implementation choices for each of these components. We then give an overview of mass spectrometers that were sent to space with the intent of probing planetary atmospheres, and discuss three instruments, the heritage of which is especially relevant to Uranus and Neptune probes, in detail.

The main part of this paper presents the current state-of-art in mass spectrometry intended for atmospheric probe. Finally, we present a possible descent probe implementation in detail, including measurement phases and associated expected accuracies for selected species.

Audrey Vorburger, Peter Wurz, Hunter Waite

Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM); Space Physics (
Cite as: arXiv:2306.09645 [astro-ph.EP] (or arXiv:2306.09645v1 [astro-ph.EP] for this version)
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Submission history
From: Audrey Vorburger
[v1] Fri, 16 Jun 2023 06:16:48 UTC (1,312 KB)

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻