- 1Physics Institute, Space Research & Planetary Science Division, University of Bern, Bern, Switzerland (dominik.belousov@unibe.ch)
- 2Institute of Applied Physics, University of Bern Bern, Switzerland (axel.murk@unibe.ch)
Radiometry is a highly accurate technique of gas spectroscopy, widely used in observations of stellar objects (e.g., molecular clouds, accretion discs), planetary atmospheres, comets and icy satellites. Since observations are usually made far from the object, the spectrum detected is a combination of many gas layers lying between the gas source and the observer. Thus, gas models are needed to properly fit observations, which becomes especially challenging in optically thick layers and with large gradients in gas profiles. In addition, optically thick layers can mask the properties of the gas source which have a direct connection with chemical and physical conditions of subsurface layers.
Our project, called WEEVIL (the Water Emission of Vapour from Ice in the Laboratory), concerns the spectroscopy of gas plumes arising from the sublimation of icy, porous and dusty media in controlled laboratory experiments, following [1]. Project objectives are: 1) verification/correction of subsurface models of icy bodies by comparing laboratory and space observations; 2) studying the capabilities of radiometry for determining subsurface material properties.
A heterodyne radiometer operating primarily at the frequency of 557 GHz (water rotational line) is being used to investigate column densities, production rates, temperatures, and outflow gas velocities of sublimed icy samples. An internal cooling system using liquid nitrogen and a cryocooler ensures stable temperature of the sample and radiometer compounds, and mitigates the impact of the vacuum chamber on the gas plume. The radiometer has been developed/procured and is undergoing the necessary sensitivity tests. The vacuum chamber is in the final design/production stage. Measured brightness temperatures by the radiometer will be compared with DSMC (direct simulation Monte Carlo) of gas and radiative transfer calculations. The radiative transfer model includes time dependence due to gas expansion and non-LTE due to non-collisional background, following [2].
[1] O. Auriacombe et al. 2022 MNRAS 515 2
[2] M. A. Cordiner et al 2022 ApJ 929 38
How to cite: Belousov, D., Mokhtari, O., Stöckli, L., Fritschi, J., Piazza, D., Murk, A., and Thomas, N.: Spectroscopy of gas plumes in the laboratory: remote sensing of comets and icy satellites, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12911, https://doi.org/10.5194/egusphere-egu25-12911, 2025.
