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Article ; Online: Deriving iron contents from past and future Venus surface spectra with new high-temperature laboratory emissivity data.

Helbert, J / Maturilli, A / Dyar, M D / Alemanno, G

2021 Volume 7, Issue 3

Abstract: In situ information on the surface composition of Venus is based on measurements of a small number of landing sites. In the laboratory, we measured the emissivity of a range of igneous rocks at temperatures up to 480°C. We show that high-temperature ... ...

Abstract	In situ information on the surface composition of Venus is based on measurements of a small number of landing sites. In the laboratory, we measured the emissivity of a range of igneous rocks at temperatures up to 480°C. We show that high-temperature laboratory spectra of basalts are consistent with the only existing multispectral data from the surface of Venus obtained by the photometers on the Venera 9 and 10 landers. We derive the FeO abundances for these landing sites of 12.2 and 9.5 weight %, respectively. From orbit, Venus' surface is only observable on the nightside through small spectral windows near 1 μm where the CO
Language	English
Publishing date	2021-01-15
Publishing country	United States
Document type	Journal Article
ZDB-ID	2810933-8
ISSN	2375-2548 ; 2375-2548
ISSN (online)	2375-2548
ISSN	2375-2548
DOI	10.1126/sciadv.aba9428
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Article ; Online: Early Archean alteration minerals in mafic-ultramafic rocks of the Barberton greenstone belt as petrological analogs for clay mineralogy on Mars

Grosch, E. / Bishop, J. / Mielke, C. / Maturilli, A. / Helbert, J.

American Mineralogist

2021

Abstract: Characterization of terrestrial analog sites is critical for detection and determination of clay miner-alogy in remote sensing studies of Mars aimed at geological, hydrological, and potentially biological investigations. In this study, we investigate a ... ...

Abstract	Characterization of terrestrial analog sites is critical for detection and determination of clay miner-alogy in remote sensing studies of Mars aimed at geological, hydrological, and potentially biological investigations. In this study, we investigate a suite of hydrothermally altered early Archean rocks from the Barberton greenstone belt (BGB) of South Africa as potential petrological, mineralogical, and spectral analogs to hydrothermally altered metabasalts and mafic-ultramafic intrusions in the martian subsurface and impact craters. We present the first spectral imaging measurements on exceptionally well-preserved early Archean mafic-ultramafic rocks from the BGB, with the aim of studying their clay mineralogy and spectral signatures. Multiple spectral analyses were conducted on different sample textures (rock powders, crushed rocks, and rock slabs) appropriate for Mars rover and remote sensing exploration. Visible/near-infrared (VNIR) and mid-IR reflectance spectra were acquired on particulate samples, while VNIR spectral imaging data were collected on rock slabs. Mid-IR emission spectra were measured for the rock slabs and grains. Spectral features are compared from these different spectral techniques to identify the minerals present in the samples and compare macroscale vs. microscale detections. The measured spectra reveal absorption bands that correspond to clay mineral-ogy of the serpentine and chlorite mineral groups, consistent with petrographic observations, as well as magnetite, olivine, quartz, feldspar, and Al-phyllosilicate. The spectral data acquired in this study expand the reference spectra data set for remote sensing studies. The implications of this study are that rocks from early Archean greenstone belts, such as those of the BGB, serve as potential clay-bearing petrological analogs for hydrothermal environments on Mars.
Subject code	550
Language	English
Publishing country	de
Document type	Article ; Online
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Article ; Online: The best temperature range to acquire reliable thermal infrared spectra from orbit.

Nestola, F / Ferrari, S / Pamato, M G / Redhammer, G / Helbert, J / Alvaro, M / Domeneghetti, M C

Scientific reports

2021 Volume 11, Issue 1, Page(s) 13212

Abstract: Solar System bodies undergo to daily and periodical variations of temperature that mainly depend on their closeness to the Sun. It is known that mineral expansion and contraction due to such variations modify the thermal infrared spectra acquired on ... ...

Abstract	Solar System bodies undergo to daily and periodical variations of temperature that mainly depend on their closeness to the Sun. It is known that mineral expansion and contraction due to such variations modify the thermal infrared spectra acquired on solid surfaces. Therefore, it becomes crucial to know the best temperature range at which the acquisition itself should be carried out to get reliable information on the mineralogy of such bodies. Here we provide the thermal expansion of olivine between 20 and 298 K determined by X-ray diffraction. Our data reveal the non-linear behaviour of silicates that undergo to low temperatures, where volume variations appear positively correlated with temperatures. Subtle bond-length variations occurring at low temperatures are then expected to minimally affect vibrational absorption positions. We suggest that thermal infrared spectra of those Solar-System surfaces that are not exceeding 300 K provide reliable information about not only the silicate mineral identification but also on their chemical composition, regardless of the instantaneous temperature.
Language	English
Publishing date	2021-06-24
Publishing country	England
Document type	Journal Article
ZDB-ID	2615211-3
ISSN	2045-2322 ; 2045-2322
ISSN (online)	2045-2322
ISSN	2045-2322
DOI	10.1038/s41598-021-92130-1
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Article ; Online: The second Venus flyby of BepiColombo mission reveals stable atmosphere over decades.

Helbert, Jörn / Haus, Rainer / Arnold, Gabriele / D'Amore, Mario / Maturilli, Alessandro / Säuberlich, Thomas / Hiesinger, Harald

Nature communications

2023 Volume 14, Issue 1, Page(s) 8225

Abstract: Studies of the Venusian mesosphere provide important information about the current state of the entire Venusian atmosphere. This includes information about the dense cloud structure, its vertical thermal profile, temperature fields, and the resulting ... ...

Abstract	Studies of the Venusian mesosphere provide important information about the current state of the entire Venusian atmosphere. This includes information about the dense cloud structure, its vertical thermal profile, temperature fields, and the resulting dynamical and meteorological processes that contribute to a deeper understanding of the climatologically different evolutionary paths of Earth and Venus. However, the last measurements were acquired in 1983 during Venera-15 mission. In this paper, results of mid-infrared spectral measurements of the Venusian atmosphere are presented. Here we show Mercury Radiometer and Thermal Infrared Spectrometer (MERTIS) measurements of the Venusian atmosphere during the second flyby of BepiColombo mission on its way to Mercury. Our Venus measurements provide reliable retrievals of mesospheric temperature profiles and cloud parameters between 60 and 75 km altitude, although MERTIS was only designed to operate in Mercury environment. Our results are in good agreement with the Venera-15 mission findings. This indicates the stability of the Venusian atmosphere on time scales of decades.
Language	English
Publishing date	2023-12-12
Publishing country	England
Document type	Journal Article
ZDB-ID	2553671-0
ISSN	2041-1723 ; 2041-1723
ISSN (online)	2041-1723
ISSN	2041-1723
DOI	10.1038/s41467-023-43888-7
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Book ; Online: Mid-infrared bi-directional reflectance spectroscopy of impact melt glasses and tektites

Morlok, Andreas / Stojic, Aleksandra N. / Weber, Iris / Hiesinger, Harald / Zanetti, Michael / Helbert, Joern

2023

Abstract: We have analyzed 14 impact melt glass samples, covering the compositional range from highly felsic to mafic/basaltic, as part of our effort to provide mid-infrared spectra (7-14 micron) for MERTIS (Mercury Radiometer and Thermal Infrared Spectrometer), ... ...

Abstract	We have analyzed 14 impact melt glass samples, covering the compositional range from highly felsic to mafic/basaltic, as part of our effort to provide mid-infrared spectra (7-14 micron) for MERTIS (Mercury Radiometer and Thermal Infrared Spectrometer), an instrument onboard of the ESA/JAXA BepiColombo mission. Since Mercury was exposed to many impacts in its history, and impact glasses are also common on other bodies, powders of tektites (Irghizite, Libyan Desert Glass, Moldavite, Muong Nong, Thailandite) and impact glasses (from the Dellen, El'gygytgyn, Lonar, Mien, Mistastin, and Popigai impact structures) were analyzed in four size fractions of (0-25, 25-63, 93-125 and 125-250 micron) from 2.5 to 19 micron in bi-directional reflectance. The characteristic Christiansen Feature (CF) is identified between 7.3 micron (Libyan Desert Glass) and 8.2 micron (Dellen). Most samples show mid-infrared spectra typical of highly amorphous material, dominated by a strong Reststrahlen Band (RB) between 8.9 micron (Libyan Desert Glass) and 10.3 micron (Dellen). Even substantial amounts of mineral fragments hardly affect this general band shape. Comparisons of the SiO2 content representing the felsic/mafic composition of the samples with the CF shows felsic/intermediate glass and tektites forming a big group, and comparatively mafic samples a second one. An additional sign of a highly amorphous state is the lack of features at wavelengths longer than about 15 micron. The tektites and two impact glasses, Irghizite and El'gygytgyn respectively, have much weaker water features than most of the other impact glasses.
Keywords	Astrophysics - Earth and Planetary Astrophysics ; Astrophysics - Instrumentation and Methods for Astrophysics ; Physics - Geophysics
Subject code	306
Publishing date	2023-01-11
Publishing country	us
Document type	Book ; Online
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Article ; Online: Survivability of the lichen Xanthoria parietina in simulated Martian environmental conditions.

Lorenz, Christian / Bianchi, Elisabetta / Poggiali, Giovanni / Alemanno, Giulia / Benesperi, Renato / Brucato, John Robert / Garland, Stephen / Helbert, Jörn / Loppi, Stefano / Lorek, Andreas / Maturilli, Alessandro / Papini, Alessio / de Vera, Jean-Pierre / Baqué, Mickaël

Scientific reports

2023 Volume 13, Issue 1, Page(s) 4893

Abstract: Xanthoria parietina (L.) Th. Fr. is a widely spread foliose lichen showing high tolerance against UV-radiation thanks to parietin, a secondary lichen substance. We exposed samples of X. parietina under simulated Martian conditions for 30 days to explore ... ...

Abstract	Xanthoria parietina (L.) Th. Fr. is a widely spread foliose lichen showing high tolerance against UV-radiation thanks to parietin, a secondary lichen substance. We exposed samples of X. parietina under simulated Martian conditions for 30 days to explore its survivability. The lichen's vitality was monitored via chlorophyll a fluorescence that gives an indication for active light reaction of photosynthesis, performing in situ and after-treatment analyses. Raman spectroscopy and TEM were used to evaluate carotenoid preservation and possible variations in the photobiont's ultrastructure respectively. Significant differences in the photo-efficiency between UV irradiated samples and dark-kept samples were observed. Fluorescence values correlated with temperature and humidity day-night cycles. The photo-efficiency recovery showed that UV irradiation caused significant effects on the photosynthetic light reaction. Raman spectroscopy showed that the carotenoid signal from UV exposed samples decreased significantly after the exposure. TEM observations confirmed that UV exposed samples were the most affected by the treatment, showing chloroplastidial disorganization in photobionts' cells. Overall, X. parietina was able to survive the simulated Mars conditions, and for this reason it may be considered as a candidate for space long-term space exposure and evaluations of the parietin photodegradability.
MeSH term(s)	Chlorophyll A ; Lichens ; Extraterrestrial Environment ; Mars ; Carotenoids
Chemical Substances	Chlorophyll A (YF5Q9EJC8Y) ; physcione (H6PT94IV61) ; Carotenoids (36-88-4)
Language	English
Publishing date	2023-03-25
Publishing country	England
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	2615211-3
ISSN	2045-2322 ; 2045-2322
ISSN (online)	2045-2322
ISSN	2045-2322
DOI	10.1038/s41598-023-32008-6
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Article ; Online: Mid-infrared emissivity of partially dehydrated asteroid (162173) Ryugu shows strong signs of aqueous alteration.

Hamm, M / Grott, M / Senshu, H / Knollenberg, J / de Wiljes, J / Hamilton, V E / Scholten, F / Matz, K D / Bates, H / Maturilli, A / Shimaki, Y / Sakatani, N / Neumann, W / Okada, T / Preusker, F / Elgner, S / Helbert, J / Kührt, E / Ho, T-M /

Tanaka, S / Jaumann, R / Sugita, S

Nature communications

2022 Volume 13, Issue 1, Page(s) 364

Abstract: The near-Earth asteroid (162173) Ryugu, the target of Hayabusa2 space mission, was observed via both orbiter and the lander instruments. The infrared radiometer on the MASCOT lander (MARA) is the only instrument providing spectrally resolved mid-infrared ...

Abstract	The near-Earth asteroid (162173) Ryugu, the target of Hayabusa2 space mission, was observed via both orbiter and the lander instruments. The infrared radiometer on the MASCOT lander (MARA) is the only instrument providing spectrally resolved mid-infrared (MIR) data, which is crucial for establishing a link between the asteroid material and meteorites found on Earth. Earlier studies revealed that the single boulder investigated by the lander belongs to the most common type found on Ryugu. Here we show the spectral variation of Ryugu's emissivity using the complete set of in-situ MIR data and compare it to those of various carbonaceous chondritic meteorites, revealing similarities to the most aqueously altered ones, as well as to asteroid (101955) Bennu. The results show that Ryugu experienced strong aqueous alteration prior to any dehydration.
Language	English
Publishing date	2022-01-18
Publishing country	England
Document type	Journal Article
ZDB-ID	2553671-0
ISSN	2041-1723 ; 2041-1723
ISSN (online)	2041-1723
ISSN	2041-1723
DOI	10.1038/s41467-022-28051-y
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Article ; Online: Resilience of Xanthoria parietina under Mars-like conditions: photosynthesis and oxidative stress response.

Lorenz, Christian / Arena, Carmen / Vitale, Ermenegilda / Bianchi, Elisabetta / Poggiali, Giovanni / Alemanno, Giulia / Benesperi, Renato / Brucato, John Robert / Garland, Stephen / Helbert, Jörn / Loppi, Stefano / Lorek, Andreas / Maturilli, Alessandro / Papini, Alessio / de Vera, Jean-Pierre / Baqué, Mickaël

Planta

2023 Volume 259, Issue 1, Page(s) 25

Abstract: Main conclusion: Xanthoria parietina survivability in Mars-like conditions was supported by water-lysis efficiency recovery and antioxidant content balancing with ROS production after 30 days of exposure. Xanthoria parietina (L.) Th. Fr. is a widespread ...

Abstract	Main conclusion: Xanthoria parietina survivability in Mars-like conditions was supported by water-lysis efficiency recovery and antioxidant content balancing with ROS production after 30 days of exposure. Xanthoria parietina (L.) Th. Fr. is a widespread lichen showing tolerance against air pollutants and UV-radiation. It has been tested under space-like and Mars-like conditions resulting in high recovery performances. Hereby, we aim to assess the mechanisms at the basis of the thalli resilience against multiple space stress factors. Living thalli of X. parietina were exposed to simulated Martian atmospheric conditions (Dark Mars) and UV radiation (Full Mars). Then, we monitored as vitality indicator the photosynthetic efficiency, assessed by in vivo chlorophyll emission fluorescence measurements (F
MeSH term(s)	Antioxidants ; Extraterrestrial Environment ; Resilience, Psychological ; Mars ; Oxidative Stress ; Photosynthesis
Chemical Substances	Antioxidants
Language	English
Publishing date	2023-12-18
Publishing country	Germany
Document type	Journal Article
ZDB-ID	208909-9
ISSN	1432-2048 ; 0032-0935 ; 1866-2749
ISSN (online)	1432-2048
ISSN	0032-0935 ; 1866-2749
DOI	10.1007/s00425-023-04290-1
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Article ; Online: Space weathering by simulated micrometeorite bombardment on natural olivine and pyroxene

Weber, I. / N.Stojic, A. / Morlok, A. / Reitz, M. / Markus, K. / Hiesinger, H. / G.Pavlov, S. / Wirth, R. / Schreiber, A. / Sohn, M. / Hübers, H. / Helbert, J.

Earth and Planetary Science Letters

A coordinated IR and TEM study.

2020

Abstract: We studied space-weathering effects caused by micrometeorite bombardment simulated by pulsed intense infrared laser, generating ∼15 mJ per pulse in high vacuum. For our investigation, we selected a natural olivine (San Carlos olivine (Fo91)) and a ... ...

Abstract	We studied space-weathering effects caused by micrometeorite bombardment simulated by pulsed intense infrared laser, generating ∼15 mJ per pulse in high vacuum. For our investigation, we selected a natural olivine (San Carlos olivine (Fo91)) and a natural pyroxene (Bamble orthopyroxene (En87)) as important rock forming minerals of the Earth upper mantle as well as key planetary minerals. Irradiated areas of powdered pressed samples were examined by optical reflection spectroscopy in a broad optical and infrared wavelength range (visible-, near-, and mid-infrared) and transmission electron microscopy to identify changes due to micrometeorite impacts. The present study aims to investigate especially the effects of micrometeorite bombardment on reflectance spectra in the mid-IR in preparation for future space missions, as well as for the MERTIS experiment onboard the BepiColombo mission. For both irradiated samples, we found a reduction in albedo and in the reflectance of characteristic Reststrahlen bands and an increase of the transparency feature. VIS and NIR spectra of both minerals show the typical darkening and reddening as described for other space-weathered samples. TEM studies revealed that space-weathered layers in olivine and pyroxene differ in their respective thickness, ∼450 nm in olivine, 100-250 nm in pyroxene, as well as in developed “nanostratigraphy” of laser-ablated material, like nanophase iron (npFe). In conclusion, our spectral and structural findings were compared to samples in which space weathering was caused by different processes. A comparison with these data demonstrates that there is no difference in optical reflectance spectroscopy, but a significant difference in the microstructure of minerals due to the weathering source in space, as there are solar wind and solar flares cause other structural and chemical changes as the bombardment with micrometeorites.
Subject code	535
Publishing country	de
Document type	Article ; Online
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Article: Olivine thermal emissivity under extreme temperature ranges: Implication for Mercury surface

Helbert, J / Nestola, F / Ferrari, S / Maturilli, A / Massironi, M / Redhammer, G.J / Capria, M.T / Carli, C / Capaccioni, F / Bruno, M

Earth and planetary science letters. 2013 June, v. 371-372

2013

Abstract: The work shows, for the first time experimentally and numerically, how the thermal emissivity spectra of a Mg-rich olivine (i.e. Mg₁.₈₄Fe₀.₁₆SiO₄, Fo₉₂Fa₈, with Fo=Mg₂SiO₄ and Fa=Fe₂SiO₄) significantly change as a function of temperature. Thermal ... ...

Abstract	The work shows, for the first time experimentally and numerically, how the thermal emissivity spectra of a Mg-rich olivine (i.e. Mg₁.₈₄Fe₀.₁₆SiO₄, Fo₉₂Fa₈, with Fo=Mg₂SiO₄ and Fa=Fe₂SiO₄) significantly change as a function of temperature. Thermal infrared spectra at two different temperatures between about 350 and 770K were collected in order to simulate the typical diurnal equatorial temperature variation of the surface of Mercury. Such temperature increase (i.e. 420K) modifies the olivine spectrum shifting in wavelength its emissivity features, simulating the spectrum of an olivine strongly enriched in iron (a Fa abundance increase from 8% to 23%). This “chameleon-like behavior” indicates that the spectroscopic investigations of the surface of Mercury must take into account the local solar time dependency to properly infer the compositions of planetary materials by remote sensing acquisition of future space missions. Although previous works already investigated the effect of temperature on IR olivine spectra, none of them definitively pointed out the reasons of the above mentioned spectral changes.
Keywords	iron ; mercury ; remote sensing ; spectroscopy ; temperature ; wavelengths
Language	English
Dates of publication	2013-06
Size	p. 252-257.
Publishing place	Elsevier B.V.
Document type	Article
ZDB-ID	1466659-5
ISSN	1385-013X ; 0012-821X
ISSN (online)	1385-013X
ISSN	0012-821X
DOI	10.1016/j.epsl.2013.03.038
Database	NAL-Catalogue (AGRICOLA)

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