20-EPN-029: VIS-NIR reflectance analysis of analogue mixture representative of young Haulani crater on Ceres

20-EPN-029: VIS-NIR reflectance analysis of analogue mixture representative of young Haulani crater on Ceres to assess the mineralogical composition of bright areas.

Visit by Fabrizio Dirri, IAPS-INAF (Italy), to TA2.8 CSS (Cold Surfaces Spectroscopy) at IPAG (France).
Dates of visit: 15-26 March 2021

Report Summary: In this project different bright areas of Haulani crater (e.g. Southern floor, i.e. ROI3 and North-east crater wall, i.e. ROI4) on Ceres have been studied by arranging different analogue mixtures and comparing them with Dawn VIR data. The end-members have been identified based on previous studies (Tosi et al. 2018, 2019) and the analogue mixtures have been produced with grain size 50-100µm for two bright crater regions. The two initial mixtures have been acquired in the VIS-NIR spectral range (0.35-4.5µm) at low temperature, i.e. from 200K to 300K similar to Haulani by using Cold Spectroscopy Facility (CSS) (IPAG, France). 

By comparing the spectral parameters (Band Center, Band Depth and FWHM of absorption bands at 2.7, 3.1, 3.4µm, spectral slope in the 1.2-1.9µm range and reflectance level at 2.1µm) with the obtained spectra of mixtures and VIR data, the best candidate to reproduce Haulani’ bright areas is the mixture A3-8. That mixture exhibits values for the 2.7BD (Antigorite, Illite), 3.1BD (NH4-Montmorillonite), 3.4 BD (NaCO3) and the 3.1 µm FWHM very close to Haulani ROI3 and ROI4. In order to better reproduce Haulani areas some improvements may be performed in the next future, e.g., by changing the dark component with a mixture of graphite plus magnetite to better reproduce the spectral slope of Haulani or by adding hydrous natrite in low percentage to the mixture, e.g. 2-8% to assess the role of this component found in Haulani bright areas and how is the contribution to 2.7 µm spectral band.

Read full report (published with kind permission of Dr Dirri).


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20-EPN-042: Reflectance spectroscopy of ammonium-bearing minerals

20-EPN-042: Reflectance spectroscopy of ammonium-bearing minerals – A tool to improve the knowledge of the surface of icy planetary bodies.

Visit by Maximiliano Fastelli, University of Perugia (Italy), to TA2.8 CSS (Cold Surfaces Spectroscopy) at IPAG (France).
Dates of visit: 09-27 November 2020

Report Summary: In the frame of the Europlanet 2024 1st TA call, reflectance VIS-NIR spectra were collected. Ten different temperature steps were chosen to collect cryogenic data: 270-245-220-180-160-140-120-100-90-270 up K.

For the samples characterized by a low temperature phase transitions (mascagnite (NH4)2SO4, sal-ammoniac NH4Cl, ammonium phosphate (NH4)H2PO4, tschermigite (NH4)Al(SO4)2·12(H2O) and ammonium nitrate NH4NO3), the measurement steps have been increased in the proximity of the expected temperature of mineral transformation. Cooling and heating experiments, using the same cooling/heating rate, were performed to break the phase transition T. In particular, mascagnite, sal-amoniac and ammonium phosphate monobasic samples showed clear and very interesting spectral bands variations during cooling, indicating that a phase transition occurred. Spectra were collected with three different grain size (150/125 – 125/80 – 80/32 μm) in the spectral range from 1 to 4.8 μm. 

The collected data will help on the interpretation of VIR remote spectra from Europa, Pluto’s moons, Enceladus and other icy celestial bodies surface where NH4 minerals have been supposed to occur. Moreover, the study of ammonium bearing minerals and their behavior at very low temperature might give information on how the phase transition affects the bands position and shapes inside the reflectance spectra. Overtones and combinations of NH4 bands are in the 1-3 μm range, whereas fundamental vibrational modes (ν1 and ν3) are present in the ~3 μm area.


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20-EPN2-088: High spectral resolution / low-temperature IR study of carbonates

20-EPN2-088: High spectral resolution / low-temperature IR study of carbonates.

Virtual visit by Simone De Angelis and Cristian Carli, IAPS-INAF(Italy), to TA2.8 CSS (Cold Surfaces Spectroscopy) at IPAG (France).
Dates of visit: 11 May – 04 June 2021

Report Summary: We planned to acquire reflectance spectra of anhydrous carbonates in the infrared range (3.2-4.6 μm), at high spectral sampling/resolution and at different cryogenic temperatures in the range 60-270K. 

The analysed materials were calcite, dolomite, siderite, natrite, malachite and magnesite; all the minerals were prepared and measured at fine powders, d<50 μm.  These measurements provide new spectral data in the IR that will be useful in the interpretation  of remote-sensing spectroscopic observations of Solar System rocky bodies such as Mars, Jovian satellites and minor bodies by current and future missions (Mars 2020, ExoMars-2022, JUICE, Europa Clipper, OSIRIS-REx). 


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