SCITEAS - The Simulation Chamber for Imaging Temporal Evolution of Analogous Samples

The SCITEAS (Simulation Chamber for Imaging Temporal Evolution of Analogous Samples) facility is an original simulation chamber aiming at studying the temporal evolution of icy analogues under low temperature and low pressure conditions.

Studying icy surface analogues

The sample, consisting of water and/or carbon dioxide ice mixed with minerals and/or organics, is placed in the chamber. By sublimation under vacuum or when exposed to a light flux, the sample evolves. We can then monitor the temperature of the sample as well as its surface reflectivity in the visible and near-infrared ranges (400-2400 nm) by producing hyperspectral cubes.

Experiments conducted in this facility have helped to interpret the surface reflectance of the comet 67P/CG done by the ESA Rosetta mission. Currently, SCITEAS is used to provide background to drive and interpret data acquired with CaSSIS (link to CaSSIS), the Bernese camera on board ESA’s mission Trace Gas Orbiter (TGO). Finally, SCITEAS is being used together with the MEFISTO (link) facility to explore the spectral changes induced by the irradiation of electrons of ions on salt-ice mixtures.

Technical description

The chamber is 30 cm in diameter and 32 cm high. Ice samples of various sizes can be placed in the chamber in dedicated sample holders.  The sample holder is surrounded by a shroud. Liquid nitrogen (boiling point of -196.15°C) flows inside this shroud to cool radiatively the sample.

A radiation shield, consisting of a stainless steel plate of 0.3 mm thickness, is placed between the chamber structure and the shroud. A quartz window on top of the sample enables to monitor the sample surface evolution with the hyperspectral imaging system positioned outside the chamber. This system consists of two cameras on top of the SCITEAS chamber: a monochromator, a CCD visible camera and a near-infrared MCT camera.

The chamber is evacuated by a turbomolecular pump assisted by a second membrane pump, allowing to reach 10-6 mbar in the chamber. The pressure in the chamber is controlled via a valve and monitored with a full pressure range gauge.

Publications

• Bernhard Jost, Antoine Pommerol, Olivier Poch, Zuriñe Yoldi, Sonia Fornasier, Pedro Henrique Hasselmann, Clément Feller, Nathalie Carrasco, Cyril Szopa and Nicolas Thomas (2017a) Bidirectional reflectance and VIS-NIR spectroscopy of cometary analogues under simulated space conditions, Planetary and Space Science, Volume 145, 14-27, https://doi.org/10.1016/j.pss.2017.07.009

• Olivier Poch, Antoine Pommerol, Bernhard Jost, Nathalie Carrasco, Cyril Szopa and Nicolas Thomas (2016a). Sublimation of ice–tholins mixtures: A morphological and spectro-photometric study,  Icarus, Volume 266, https://doi.org/10.1016/j.icarus.2015.11.006.

• Poch, O., Pommerol, A., Jost, B., Carrasco, N., Szopa, C., & Thomas, N. (2016b). Sublimation of water ice mixed with silicates and tholins: Evolution of surface texture and reflectance spectra, with implications for comets. Icarus, 267, 154-173.

• Pommerol, A., Jost, B., Poch, O., El-Maarry, M.R., Vuitel, B. and Thomas, N. The SCITEAS experiment: Optical characterizations of sublimating icy planetary analogues (2015) Planetary and Space Science, 109-110, pp. 106-122. DOI: 10.1016/j.pss.2015.02.004

• El-Maarry, M. R., W. A. Watters, Z. Yoldi, A. Pommerol, D. Fischer, U. Eggenberger and N. Thomas  (2015), Field investigation of dried lakes in western United States as an analogue to desiccation fractures on Mars, J. Geophys. Res. Planets, 120, 2241–2257, doi:10.1002/2015JE004895.