LOSSy - Laboratory for Outflow Studies of Sublimating Materials
In the laboratory, we are preparing and analyzing analogs of planetary or cometary surfaces composed of dust-ice mixtures to study their optical properties and dynamic evolution under simulated conditions (sublimation, outflow etc.). This laboratory work gives us the ability to predict photometric properties or to interpret observational data of planetary or cometary surfaces.
Our current laboratory setups consist of:
- a Setup for Production of Icy Planetary Analogs (SPIPA) capable of producing rapidly a thick layer of water ice particles,
- an Optical Coherence Tomography instrument (OCTOPUS) to characterize the texture of the surface of our samples that is responsible for the scattering of the light,
- a gonio-radiometer (PHIRE-2) working at sub-zero temperature and enabling to measure the bidirectional reflectance and bulk physical properties of icy samples,
- a thermal-vacuum chamber equipped with a hyperspectral imaging system (SCITEAS) for the study of the spectral evolution of dusty-ice mixtures at low pressure and low temperature,
- and a desiccation experiment setup working at ambient conditions.
Sample production and characterization
The preparation of analogs of planetary or cometary surfaces for our measurements requires the use of judiciously chosen and accurately characterized materials including ice, minerals and organic matter. In addition to a collection of mineral and organic materials, we have developed an ice production machine called SPIPA for Setup for Production of Icy Planetary Analogs, capable of producing rapidly a thick layer of water ice particles needed for our measurements. We can prepare different types of mixtures of this ice with mineral and organic contaminants. The surface texture of the samples is characterized using our OCTOPUS facility, for Optical Coherence Tomography Of Planetary Ultra-cold Samples, capable to image the 3D structure of a 10*10 mm area at a resolution of a few μm and down to depths of few mm. This instrument probes the same layer of the sample that is responsible for the scattering of the light, measured by our PHIRE-2 and SCITEAS setups described below.
The PHIRE-2 (for Physikalisches Institut Radiometer Experiments) facility is designed to characterize the VIS–NIR Bidirectional Reflectance Distribution Function (BRDF) and some complementary bulk physical properties of planetary analog samples containing water ice. The central part of the facility is a highly accurate gonio-radiometer (PHIRE-2) operating in the VIS–NIR spectral range (400–1100 nm) installed in a large laboratory freezer to permit operations at sub-zero temperatures. Its development was based on the experience gained on the gonio-radiometer PHIRE-1. The photometric measurements are complemented by a detailed simultaneous characterization of the physical state and possible temporal evolution of the samples using a combination of macro- and micro-imaging, thermal, electrical and sample mass measurements. PHIRE-2 is designed to support the interpretation of current and future remote sensing and in-situ datasets on icy planetary objects with a special emphasis on cometary nuclei, Martian polar regions and Jovian satellites.
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 cometary analogues under low temperature and low pressure conditions. The temperature field in the sample as well as its optical properties and surface texture are investigated in situ in the chamber, using sensors and a visible to near-infrared hyperspectral imaging system. Experiments conducted in this facility aims to provide the necessary background to drive and interpret future investigations on comet Churyumov-Gerasimenko by the ESA Rosetta mission. SCITEAS can also simulate Mars surface temperature and pressure conditions, providing essential laboratory data for the interpretation of VIS-NIR remote sensing datasets of the Martian surface.
Mars desiccation experiment
Extensive mapping of polygonal fracture patterns on the surface of Mars suggests that polygonal desiccation crack patterns may be a common feature that is present in various size scales ranging from cm scale up to hundreds of meters. Formed by surface evaporation and/or migration of subsurface water, desiccation crack patterns represent key indicators of the past climatic conditions at the surface of Mars. As such, this work has important implications for our understanding of the history of liquid water on Mars. The desiccation experiments performed in our group on wet soil analogues in ambient and Mars-like atmospheric conditions aim to understand the processes involved on the cmscale (i.e., involving only surface evaporation), which may later be extrapolated accordingly to account for larger scales.
We plan to extend our laboratory capabilities to investigate in more detail dust-gas outflows and dust-ice interactions using the illumination of a solar simulator on icy surface samples, analogs of comets, Mercury, Mars and icy outer solar system moons.
Research activities related to the Center for Space and Habitability
Our group actively collaborate to the Center for Space and Habitability (CSH) of the University of Bern by conducting investigations of the spectro-photometric properties of mixtures between ice, minerals and biotic or abiotic organic matter. Taking advantage of the PHIRE-2 and SCITEAS facilities described above, we aim to assess the potential of optical remote-sensing methods to detect living organisms at the surface of various planetary bodies, including exoplanets.
Space Research & Planetary Sciences Division Web Site