The Japanese MMX sample return mission to Phobos by JAXA will carry a rover developed by CNES and DLR that will be deployed on Phobos to perform in situ analysis of the Martian moon’s surface ...properties. Past images of the surface of Phobos show that it is covered by a layer of regolith. However, the mechanical and compositional properties of this regolith are poorly constrained. In particular, from current remote images, very little is known regarding the particle sizes, their chemical composition, the packing density of the regolith as well as other parameters such as friction and cohesion that influence surface dynamics. Understanding the properties and dynamics of the regolith in the low-gravity environment of Phobos is important to trace back its history and surface evolution. Moreover, this information is also important to support the interpretation of data obtained by instruments onboard the main MMX spacecraft, and to minimize the risks involved in the spacecraft sampling operations. The instruments onboard the Rover are a Raman spectrometer (RAX), an infrared radiometer (miniRad), two forward-looking cameras for navigation and science purposes (NavCams), and two cameras observing the interactions of regolith and the rover wheels (WheelCams). The Rover will be deployed before the MMX spacecraft samples Phobos’ surface and will be the first rover to drive on the surface of a Martian moon and in a very low gravity environment.
Graphic Abstract
Mineralogy is the key to understanding the origin of Phobos and its position in the evolution of the Solar System. In situ Raman spectroscopy on Phobos is an important tool to achieve the scientific ...objectives of the Martian Moons eXploration (MMX) mission, and maximize the scientific merit of the sample return by characterizing the mineral composition and heterogeneity of the surface of Phobos. Conducting in situ Raman spectroscopy in the harsh environment of Phobos requires a very sensitive, compact, lightweight, and robust instrument that can be carried by the compact MMX rover. In this context, the Raman spectrometer for MMX (i.e., RAX) is currently under development via international collaboration between teams from Japan, Germany, and Spain. To demonstrate the capability of a compact Raman system such as RAX, we built an instrument that reproduces the optical performance of the flight model using commercial off-the-shelf parts. Using this performance model, we measured mineral samples relevant to Phobos and Mars, such as anhydrous silicates, carbonates, and hydrous minerals. Our measurements indicate that such minerals can be accurately identified using a RAX-like Raman spectrometer. We demonstrated a spectral resolution of approximately 10 cm
−1
, high enough to resolve the strongest olivine Raman bands at ~ 820 and ~ 850 cm
−1
, with highly sensitive Raman peak measurements (e.g., signal-to-noise ratios up to 100). These results strongly suggest that the RAX instrument will be capable of determining the minerals expected on the surface of Phobos, adding valuable information to address the question of the moon’s origin, heterogeneity, and circum-Mars material transport.
Graphical Abstract
Raman spectrometers will be part of the scientific payload of the future lander missions to Mars, icy moons, and asteroids. Their primary task is the search for life including the detailed ...characterization of the planetary environment. H2O/OH−‐bearing minerals are essential for biological processes; thus, their investigation will have a special focus. Cyclic temperature variations on planetary surfaces, for example, on Mars between 300 and 140 K from summer midday to winter night, induce re‐organization of the internal mineral structures, which can be monitored by Raman spectroscopy. Therefore, temperature dependent changes in Raman spectra under step‐wise cooling/re‐heating of typical planetary surface related H2O/OH−‐bearing minerals (e.g., carnallite, natrolite, gypsum, phlogopite, talc, and tremolite) are the focus of this work. Spectra were taken under space relevant simulated conditions, from vacuum and cryogenic temperature to room conditions, including those that resemble the Martian surface atmosphere. Special attention was dedicated to the typical vibrational stretching modes of H2O/OH−‐bearing minerals. H2O‐bearing minerals exhibit significantly different temperature related changes when compared to OH−‐bearing minerals. We observed the formation of an ice‐like Raman spectrum during step‐wise deep cooling of carnallite. Gypsum shows a blue shift of the H2O band with decreasing temperature. All other investigated minerals display no significant variations over the entire Raman relevant spectral range. The results of this study are be made available in a Raman database of the flight Raman instruments.
In preparation for planetary space missions, six hydrous minerals were investigated. During step‐wise deep cooling under evacuated conditions, the formation of an ice‐like Raman spectrum of carnallite (KMgCl3 × 6H2O) was monitored. All other minerals show no or only weak variation over the spectral range from 3000 to 3800 cm−1.
The success of an astrobiological search for life campaign on Mars, or other planetary bodies in the Solar System, relies on the detectability of past or present microbial life traces, namely, ...biosignatures. Spectroscopic methods require little or no sample preparation, can be repeated almost endlessly, and can be performed in contact or even remotely. Such methods are therefore ideally suited to use for the detection of biosignatures, which can be confirmed with supporting instrumentation. Here, we discuss the use of Raman and Fourier Transform Infrared (FT-IR) spectroscopies for the detection and characterization of biosignatures from colonies of the fungus Cryomyces antarcticus, grown on Martian analogues and exposed to increasing doses of UV irradiation under dried conditions. The results report significant UV-induced DNA damage, but the non-exceeding of thresholds for allowing DNA amplification and detection, while the spectral properties of the fungal melanin remained unaltered, and pigment detection and identification was achieved via complementary analytical techniques. Finally, this work found that fungal cell wall compounds, likely chitin, were not degraded, and were still detectable even after high UV irradiation doses. The implications for the preservation and detection of biosignatures in extraterrestrial environments are discussed.
The discovery of life on other planets and moons in our solar system is one of the most important challenges of this era. The second ExoMars mission will look for traces of extant or extinct life on ...Mars. The instruments on board the rover will be able to reach samples with eventual biomarkers until 2 m of depth under the planet’s surface. This exploration capacity offers the best chance to detect biomarkers which would be mainly preserved compared to samples on the surface which are directly exposed to harmful environmental conditions. Starting with the studies of the endolithic meristematic black fungus Cryomyces antarcticus, which has proved its high resistance under extreme conditions, we analyzed the stability and the resistance of fungal biomarkers after exposure to simulated space and Mars-like conditions, with Raman and Gas Chromatography–Mass Spectrometry, two of the scientific payload instruments on board the rover.
Shock-produced melt veins in the Martian shergottite Dar al Gani 670 crosscut large olivine crystals. The upper part of one of these crystals appears to be sheared off and displaced along the shock ...vein. From the olivine–vein interface small lamellae of ringwoodite grow into the host crystal. The ≤1–3µm wide and up to 20µm long lamellae consist of small bands and blocks and are orientated along specific crystallographic orientations. Texture and composition, i.e., more Fe-rich than the host olivine, indicate that lamellae formed via incoherent diffusion-controlled growth. It is suggested that a combination of high particle velocities and shock-induced defects lead to enhanced diffusion rates. In addition, shearing caused grain size reduction allowing rapid Fe–Mg interchange and induced lattice defects serving as nucleation sites for ringwoodite. Crystallographic orientation of ringwoodite lamellae indicates that during shock deformation the 001{hk0} slip system was activated in olivine. Natural high-pressure phases in Martian meteorite allow to constrain phase transitions taking place in the inaccessible Earth's mantle. High-pressure shear instabilities of olivine at subduction zones in 400–700km depth are considered being responsible for deep earthquakes. At such p–T-conditions, breakdown of olivine results in formation of ringwoodite filled micro-anticracks which interact with each other finally leading to catastrophic shear failure. Our results strongly suggest that shearing itself contributes to a runaway process of enhanced ringwoodite formation and, thus, reinforces catastrophic material failure that may result in deep earthquakes.
•Ringwoodite growths in an olivine grain crosscut and sheared along a shock vein.•Ringwoodite lamellae formed via incoherent diffusion-controlled growth.•Ringwoodite formation is shear-induced.•High-pressure shear instabilities of olivine may result in deep earthquakes.
We investigated the potential of a laser selection in the broad optical range, from ultraviolet through visible to infrared (excitation wavelengths of 325, 532, 785, and 1064 nm) for combined ...analysis of Earth‐relevant extremophiles (Xanthoria elegans, Buellia frigida, and green alga of Circinaria gyrosa), carbohydrate molecules, as well as Mars and Moon surface regolith simulants as analog mineral mixtures (P‐MRS, S‐MRS, LRS, and JSC‐1). We show that the optimization of the laser photon energy provides (for at least one of the chosen excitation wavelengths) high‐end quality Raman spectra for each examined sample. In most cases, the infrared spectral range is advanced for biological samples, while an excitation in the visible and ultraviolet spectral range is often favorable or at least sufficient for accurate identification/resolution of mineral phases under the illuminated laser spot on the planetary surface simulants. Ultraviolet excitation does not always deliver significant contrast of the Raman Stokes responses to the induced photoluminescence in the studied biomolecules. Most prominent features in the Raman spectra of the biological samples are assigned to their specific pigments, also considered as biomolecular signatures of the extremophiles. The critical issue of specific advantages and limitations of each particular excitation source implies study for gaining scientific return from Raman spectroscopy for exobiological prospecting, for instance, the best trade between a single or dual excitation wavelength(s) for both biological and geological spectral data.
This study confirms the critical importance of a choice of an appropriate wavelength of an excitation laser for avoiding/reduction of photoluminescence in Raman scattering spectroscopy and by this achieving the best possible contrast of Raman signatures for strongly luminescent biological samples and mineral mixes simulating planetary surface regolith, relevant to astrobiology. Infrared excitation is primarily desired for the best performance for biological molecules, offering not only a low‐PL response but also a low potential damage than the short‐wavelength lasers. Identification of mineral phases is feasible in the entire UV‐NIR range, while a green laser with a combination of a silicon‐based CCD offers the best signal‐to‐noise and can return, therefore, reasonable Raman signals at relatively low laser intensity.
Mineral alteration is a possible side effect of spectroscopic
techniques
involving laser ablation, such as laser-induced breakdown spectroscopy
(LIBS), and is related to the interaction of the ...generated plasma
and ablated material with samples, dust, or ambient atmosphere. Therefore,
it is essential to understand these interactions for analytical techniques
involving laser ablation, especially for space research. In this combined
LIBS–Raman analytical study, pyrite (FeS
2
) and pyrrhotite
(Fe
1–
x
S)
samples have been consecutively measured with LIBS and Raman spectroscopy,
under three different atmospheric conditions: ∼10
–4
mbar (atmosphereless body), ∼7 mbar, and Martian atmospheric
composition (Martian surface conditions), and 1 bar and Martian atmospheric
composition. Furthermore, a dust layer was simulated using ZnO powder
in a separate test and applied to pyrite under Martian atmospheric
conditions. In all cases, Raman spectra were obscured after the use
of LIBS in the area of and around the formed crater. Additional Raman
transitions were detected, associated with sulfur (pyrite, 7.0 mbar
and 1.0 bar), polysulfides (all conditions), and magnetite (both minerals,
1.0 bar). Magnetite and polysulfides formed a thin film of up to 350–420
and 70–400 nm in the outer part of the LIBS crater, respectively.
The ZnO-dust test led to the removal of the dust layer, with a similar
alteration to the nondust pyrite test at 7.0 mbar. The tests indicate
that recombination with the CO
2
-rich atmosphere is significant
at least for pressures from 1.0 bar and that plasma–dust interaction
is insignificant. The formation of sulfur and polysulfides indicates
fractionation and possible loss of volatile elements caused by the
heat of the LIBS laser. This should be taken into account when interpreting
combined LIBS–Raman analyses of minerals containing volatile
elements on planetary surfaces.
Raman spectra of the Markovka chondrite (H4) Voropaev, Sergey; Böttger, Ute; Pavlov, Sergey G. ...
Journal of Raman spectroscopy,
March 2022, 2022-03-00, 20220301, Letnik:
53, Številka:
3
Journal Article
Recenzirano
Odprti dostop
Raman spectroscopy and scanning electron microscopy methods were used to study the fragment of the Markovka (H4 chondrite) meteorite. A characteristic set of silicate minerals (olivine and pyroxene), ...oxides and hydroxides (maghemite and goethite), troilite, and carbonates (aragonite) was determined. The structural features revealed by Raman spectroscopy allow us to draw important conclusions on thermal history of the parent body including both the temperature experienced by the rock on the parent body and their cooling rate as well as the constraints on the size of the parent body and the Mg composition of the assumed fluid.
Raman spectroscopy and scanning electron microscopy methods were used to study the fragment of the Markovka (H4 chondrite) meteorite. A characteristic set of silicate minerals (olivine and pyroxene), oxides and hydroxides (maghemite and goethite), and carbonates (aragonite) was determined. The structural features revealed by Raman spectroscopy allow us to draw important conclusions about both the temperature of the parent body and the Mg composition of the assumed fluid.
Abstract Innovative techniques are required for the in situ investigation of the surfaces of planetary bodies when landings are planned. Raman spectroscopy turned out as an excellent tool for fast ...mineralogical analyses on space missions. Contribution from a photoluminescence signal is not unexpected and is likely to be even more pronounced on celestial surfaces with a dilute or absent atmosphere exposed to strong space weathering, for example, micrometeorite bombardment. Such signals were found, for example, in Raman analysis of the probes from sample‐return missions. While photoluminescence is generally considered as an accompanying undesired product in the Raman spectral measurement, our studies show that some analytical information can be derived from this signal, and even more, due to the specific correlation of luminescence intensity with space weathering products. Therefore, we investigate the Raman spectra alteration of characteristic rock‐forming mineral mixtures (olivine, pyroxene and plagioclase) by micrometeorite bombardment, which is simulated by nanosecond‐pulse laser irradiation. The changes in the minerals are strongly dependent on the composition and structure. They range from disappearing changes in the minerals with simple chemistry and structure to complete amorphization of minerals with relatively low melting enthalpy. With Raman spectroscopy, we found out that the photoluminescence signals show resonant or anti‐resonant changes to specific mineral phases and amorphization. Furthermore, ablation‐induced iron nanoparticles of minerals containing Fe are detectable by Raman spectroscopy due to their alteration into iron oxides. Trapped volatiles in the matrices are analysed due to the formation of the compounds containing them. This broad spectrum of results indicating specific change phenomena due to space weathering can be effectively used for in situ Raman analysis in planetary missions.
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