MITM5
Session assets
Introduction: The JAXA Martian Moons Exploration (MMX) mission [1] will deploy the French-German IDEFIX rover (Fig. 1) to the surface of Phobos [2]. The IDEFIX rover will attempt wheeled-locomotion on a low-gravity surface for the first time thus providing a unique opportunity to study the surface properties of Phobos and the behaviour of regolith on small-bodies.
Figure 1 (left) The MMX IDEFIX rover (image credit: JAXA). (right) A WheelCam (image credit: CNES)
The WheelCams: The IDEFIX rover includes two WheelCams, placed on the underside of the rover and each aimed at a different rover wheel [3]. The WheelCam image sensors are panchromatic and consist of a 2048 by 2048 array. The optics provide a field of view of 32.5° and a pixel resolution of approximately 100 μm at the centre of the image. The WheelCams are also equipped with LEDs to illuminate the scene; white LEDs to be used while driving, and three colour LEDs (590, 720 and 880 nm) to allow for multispectral imaging. The WheelCams can be operated in both an imaging and a movie mode. Typical movie frame rates are expected to be 1 image per mm moved for the front WheelCam, 1 image per cm moved for the rear WheelCam (the anticipated rover speed is ~0.1-4 mm/s).
Science Objectives of the WheelCams: The WheelCam images will be used to characterize the general grain properties of the regolith (size distribution, morphological parameters [3]), within the limits of the resolution. The WheelCam images will also be used to determine the adhesive properties of regolith particles stuck to the rover wheels and the depth of the wheel sinkage, which is closely linked to the load bearing strength [4] and friction angle of the regolith [5]. The linear and angular velocities of the wheel will be calculated from the WheelCam images in order to provide measurements of the traction and slippage of the wheel. In addition to providing important information about the performance of the locomotion, this also provides the shearing characteristics of the regolith [6,7]. Topographical reconstruction of the rover tracks, talus and tailings behind the wheels [8] will provide additional constraints on the physical properties of the regolith. Finally, using the coloured LEDs it will be possible to study the mineralogical composition of the regolith from reflectance and albedo measurements, and to asses space weathering by comparing inside and outside of the rover tracks.
Preparing for the WheelCam analyses: In anticipation of the MMX mission, we have developed the MMX WheelCam testbed (Fig. 2, [9]) that recreates the scene that the WheelCams will observe during the mission (Fig. 3). The main objective of the testbed is to develop the image processing tools for the WheelCams. The testbed is instrumented with multiple sensors allowing measurements to be made of the sinkage of the wheel into the soil, and the slippage (essentially the loss of traction) of the wheel. The testbed also includes the MMX rover wheel, camera baffles, the LEDs and blackout panels to perform trials in representative lighting conditions.
Figure 2. Two different views of the MMX WheelCam testbed at ISAE-SUPAERO.
Figure 3. WheelCam approximate field of views, as generated by the WheelCam testbed. (left) Front WheelCam perspective. (right) Rear WheelCam perspective.
We also perform Discrete Element Method simulations [10] in order to understand the influence of the low gravity environment on sinking and driving behaviour (Fig. 4; [11, 12]]. This is essential to ensure an accurate determination of the regolith properties from the wheel – surface interactions.
Figure 4. Snapshot from a rolling simulation where gravity is 0.006 m/s2 and the rotational velocity is 0.65 rad/s [11,12].
Conclusions: This presentation will discuss the expected science return from the MMX IDEFIX rover WheelCams and provide a status of the preparatory activities and image processing pipelines under development.
Acknowledgments: We acknowledge CNES funding.
References: [1] Kuramoto, K. et al. EPS (2022), [2] Michel et al., EPS (2022), [3] Robin, C. et al., Nat. Comm. 2024, [4] Bigot, Lombardo et al. [5] Sullivan et al., JGR-Planets (2011), [6] Maimone, M. et al. J. Field Robotics (2007), [7] Reina, G. et al. IEEE/ASME Trans. On Mechatronics (2006), [8] Amsili, A. et al. EPSC 2024, [9] Passoni, L. et al., LPSC (2021), [10] Sunday, C. et al., MNRAS (2020), [11] Sunday, C., et al. EPSC (2022), [12] Sunday, C. PhD Thesis, ISAE-SUPAERO (2022).
How to cite: Murdoch, N., Sunday, C., Amsili, A., Tardivel, S., Robin, C., Vivet, D., Delton, P., Smith, J., Tur-Garcia, T., LaLucaa, V., Theret, N., Bertrand, J., Baroukh, J., Vernazza, P., Groussin, O., Jorda, L., Biele, J., Miyamoto, H., Ulamec, S., and Michel, P. and the MMX Rover Locomotion Team: The science goals of the IDEFIX rover WheelCams, Europlanet Science Congress 2024, Berlin, Germany, 8–13 Sep 2024, EPSC2024-1185, https://doi.org/10.5194/epsc2024-1185, 2024.
Introduction: Quantifying and mapping the precise amount of water ice in the subsurface of the Moon has proven challenging using only remote sensing data. However, this knowledge is crucial for planning long-term exploration missions that rely on the utilization of potential water reserves. Higher-resolution data and ground truth can be obtained by in situ measurements. Rover missions, such as NASA’s VIPER [1], promise to be highly valuable assets for lunar exploration as their mobility allows to analyse the lateral distribution of volatiles at much higher resolution than presently possible. Additionally, ESA’s upcoming PROSPECT mission [2] on a stationary lander will analyse the vertical distribution of water up to 1 m depth.
To somewhat remedy mass constraints and life-time limitations while still enabling scientific measurements, electric permittivity sensors can be utilized: Permittivity sensors measure the electric permittivity (and conductivity) in a low-frequency band, and are lightweight, have low impact on technical system budgets, and can acquire measurements quickly. Thereby, the soil’s porosity and water ice content can be deduced. As a drawback, the measurement depth of these sensors is limited to a few centimetres of measuring depth, on the same order of magnitude as the electrode size. Missions such as Cassini-Huygens [3] and Rosetta [4] have successfully demonstrated the concept and PROSPECT will feature a permittivity sensor integrated into its drill to characterize the vertical distribution of the lunar sub-surface at its landing position [2].
To combine the strengths of both rover mobility and permittivity sensor characteristics, small permittivity sensors can be attached to various surfaces, including rover wheels. At TUM, we currently develop such instrument arrangements, called patch electrodes, which will be used to identify and map the lateral abundance and state of lunar water ice at the lunar poles.
Background: Electrical permittivity is a measure of the electric polarizability of a dielectric and thus describes its ability to store energy in an electric field. Any mixture of materials between two electrodes and their respective relative permittivity influences the system’s electric capacitance. In the context of planetary exploration, this phenomenon can be exploited as the relative (static) permittivity of vacuum (=1), dry regolith (~5–8), and water ice (~80–100) differ significantly in both magnitude and behavior in the frequency domain over temperature [6]. Here, especially low temperatures are of interest [7].
Measuring the capacitance of a calibrated system thus allows for the deduction of the material’s bulk effective electric permittivity. The composition is subsequently calculated using simulations of the electric field’s geometry and mixing rules linking the effective permittivity to the volume shares and individual relative permittivity, for example Looyenga’s rule [8]. Figure 1 shows the expected effective relative static permittivity at a temperature of -20 °C for the three-component mixture of water ice, regolith, and vacuum and Looyenga’s mixing law. Under the assumption of known bulk density, the mass of volatiles in the sample can be determined by regression of the differences between multiple frequencies.
Experimental Setup: For the investigations under cryogenic conditions, a pulse tube cooled facility was used. It enables cooling a small sample (~10 cm3) to temperatures below -150 °C.
Figure 1: Expected effective relative permittivity for the investigated mixture. Stars indicate the investigated mixtures. Adapted from [9].
Possible compositions of samples are indicated in Figure 1 with star markers. White lines depict two different regolith volume shares and two different ice-to-vacuum ratios. The values for investigated regolith samples are selected to represent loosely poured regolith and compacted regolith, while binary water/air mixtures represent loose and compacted snow. Additionally, calibration without the container was performed before and after the campaign to characterize the instrument background/noise.
Sample temperatures ranged from -150 °C to 0 °C and were measured on the sample container and on the electrode using thin Type-K thermocouples. Multiple repetitions were performed for all setups. The measurements were taken with a commercial microcontroller (Teensy 4.1) on a custom front-end electronics board and processed using Discrete Fourier Transformation as described in [9].
Figure 2: Capacitances derived from measurements with the patch permittivity sensor for (A) pure water, (B) JSC-1A regolith, (C) air and (D) a mixture of JSC-1A with 10 % water by weight.
Preliminary Results: Figure 2 shows the bulk capacitance over frequency derived from Fourier analysis evaluated from measurements with the setup for temperatures between -40 °C to 0 °C in approximately 10 °C intervals. The samples were distilled water, dried JSC-1A (moisture content < 0.1 %), air, and a mixture of dry simulant with 10 % by weight of distilled water. The base excitation frequency of 6.25 Hz and the 20 kHz sampling frequency were chosen based on experience from previous studies.
The capacitances for JSC-1A and air follow the expected trend of an approximately constant relative permittivity over frequency and show a good signal-to-noise ratio (> 10, not shown) up to around 500 kHz. The mixture exhibits a capacitance ranging between its individual constituents, which qualitatively matches the expected mixing law. The magnitude and frequency behaviour of the measurements amongst each other shows the technique’s robustness and repeatability and are similar to published data [5,7]. The capacitancesre also in the expected range based on numerical simulations (pF).
Outlook: Further improvements both to the instrument as well as to the experimental setup are foreseen in the near future. The signal-to-noise ratio can be increased at higher frequencies with a software-based increase in base excitation frequency. A shift to lower frequencies may yield a better resolution at the spectrums lower end. Other regolith simulants (e.g. NU-LHT-2M or EAC-1) will also be investigated to gain confidence in the mixing laws. The results from this study will directly feed into the investigation of the sensor’s sensitivity, accuracy, and detection limits, as well as its applicability for further exploration missions.
References: [1] Colaprete et al. (2021) NESF & ELS 2021 [2] Trautner R. et al (2024), Front. Space Tech. [3] Fulchignoni, M. et al. (2002) Space Sci. Rev. [4] Seidensticker, K. J. et al. (2007) Space Sci. Rev. [5] Nurge, M. A. (2012) Planet. Space Sci. [6] Sihvola, A. (2000) Subsurface Sensing Tech. and Appl. [7] Trautner R. et al. (2021) Meas. Sci. Technol [8] Looyenga (1965) Physica [9] Gscheidle C. et al (2024), Front. Space Tech.
How to cite: Gscheidle, C. and Reiss, P.: Investigation of Hydrated Regolith Simulant with Patch Permittivity Sensors for Planetary Exploration under Cryogenic Conditions, Europlanet Science Congress 2024, Berlin, Germany, 8–13 Sep 2024, EPSC2024-559, https://doi.org/10.5194/epsc2024-559, 2024.
Introduction: In December 2020, China’s Chang’E-5 (CE-5) mission successfully landed in the northeastern part of Oceanus Procellarum on the Moon and achieved its goal of collecting lunar surface samples[1]. Chang’E-6 (CE-6) is China’s second lunar sample return mission following the CE-5 mission, and were launched on 3rd May 2024 . The CE-6 landing zone has been selected to lie within the lunar farside South Pole–Aitken (SPA) basin in the southern part of the Apollo basin[2]. Both CE-5 and CE-6 missions are equipped with the Lunar Mineralogical Spectrometer (LMS) to conduct surface spectral scanning to obtain the mineralogical infromation of the sampling area. The LMS can acquire hyperspectral data from 480 nm to 3200 nm[3]. Due to in-orbit working time and condition limitations, LMS could not complete whole sampling area scanning using hyperspectral detection mode and has to adopt multispectral detection mode. In this study, we mainly introduced the design of band selection for the LMS multispectral detection mode.
Designed LMS multi-bands for CE-5 mission: Remote sensing data reveals that the spectra of the CE-5 landing area exhibit longer-wavelengths ~1 μm and 2 μm absorptions, indicating that the CE-5 mare basalts are primarily composed of high-Ca pyroxene (HCP). Spectra of CE-5 landing area also show a much weaker 2 μm absorption relative to their 1 μm absorption, resembling the spectral characteristics of olivine[5]. In addition, CE-5 landing area contains a large amount of ejected materials from surrounding regions, including basaltic materials dominated by low-Ca pyroxene (LCP) from western old IM basaltic regions and materials dominated by plagioclase from the eastern highlands. Products associated with volcanic activity such as volcanic glass and ilmenite are also likely to contribute to the material in CE-5 landing area. Considering the spectral features of these mineral/glass and taking into account wavelength positions that can be used to estimate Fe, Ti and maturity as well as OH-/H2O, we finally selected 20 bands combination for CE-5 LMS (Table 1).
Optimization of multi-bands for CE-6 mission: The pyroxene composition of CE-6 landing area has changed significantly, ranging from Mg-rich LCP to Fe, Ca-rich HCP[2]. Spectral interpretation of pyroxene compositions of CE-6 landing area will greatly influence the analysis of the origin of the returned samples (mantle or lower crust). Therefore, for CE-6 mission, we increased the number of the selected bands around ~1 μm and 2 μm absorption to more accurately dipict the variation of absorption center of lunar soils resulting from the changing composition of pyroxene. Besides, to better characterize OH-/H2O absorption, we optimized the positions and increased the number of bands for 2200 nm-3200 nm regions (Table 1).
Evaluation on displaying spectral features:
In general, the designed multi-bands can well display the hyperspectral features (measured by RELAB) of mineral/glass separated from lunar soils. LCP exhibits a shorter-wavelength absorption ~2000 nm, consistent with its hyperspectral data. HCP shows a flattening between ~2000 nm and ~2200 nm, indicating that its absorption center should be located between these two bands. The multispectral data allows for the effective display of olivine’s broader 1 μm absorption, and the hyperspectral features of the three types of lunar volcanic glasses are also well reproduced, particularly the longward 1 μm and shortward 2 μm wide absorptions. Compared to the multi-bands spectra of CE-5, the designed bands combination for CE-6 seems to be more efficient in reflecting the absorptions around ~2 μm and ~2.8 μm because of the optimization and increased number of bands selected for these two spectral regions.
References: [1] Li C. et al. (2022) NSR, 9, 2, nwab188. [2] Zeng X. et al. (2023) Nature Astronomy, 7, 1188-1197. [3] He Z. (2019) J. Appl. Remote Sens, 13(2). [4] Liu D. et al. (2002) Nature Communictions,13, 5965. [5] Staid M. I. et al. (2011) J. Geophys. Res. Planets, 116, E6.
Figure 1. Comparison between hyperspectral and multispectral data of minerals and glasses composing lunar soils. The multispectra were obtained by re-sampling the hyperspectra according to the spectral response function of CE-5 LMS multispectral detection mode.
Figure 2. Comparison between hyperspectral and multispectral data of minerals and glasses composing lunar soils. The multispectra were obtained by re-sampling the hyperspectra according to the spectral response function of CE-6 LMS multispectral detection mode.
Table 1 Designed LMS multi-bands
|
CE-5 (nm) |
CE-6 (nm) |
Main Application |
|
485 |
485 |
Ilmenite, TiO2 |
|
560 |
560 |
Ilmenite, TiO2 |
|
640 |
640 |
Ilmenite, Black bead |
|
750 |
750 |
1μm absorption shoulder, maturity, FeO and TiO2 |
|
850 |
|
olivine |
|
900 |
900 |
LCP |
|
|
925 |
LCP |
|
950 |
950 |
LCP/HCP, maturity, FeO and TiO2 |
|
|
970 |
HCP |
|
1000 |
1000 |
HCP |
|
1050 |
1050 |
HCP, olivine |
|
1100 |
1100 |
olivine, volcanic glass |
|
1250 |
1250 |
olivine, plagioclase, volcanic glass |
|
1450 |
1450 |
1μm absorption shoulder, olivine |
|
1550 |
1550 |
1μm or 2μm absorption shoulder, plagioclase |
|
1800 |
1800 |
LCP |
|
|
1900 |
LCP |
|
2000 |
2000 |
LCP/HCP |
|
|
2100 |
HCP |
|
2200 |
|
HCP |
|
|
2250 |
HCP |
|
|
2540 |
LCP/HCP shoulder, OH-/H2O shoulder |
|
2600 |
|
OH-/H2O shoulder |
|
|
2750 |
OH-/H2O shoulder |
|
2800 |
|
OH-/H2O |
|
|
2850 |
OH-/H2O |
|
|
2950 |
OH-/H2O |
|
3000 |
3000 |
OH-/H2O |
|
|
3100 |
OH-/H2O |
|
3200 |
|
OH-/H2O |
How to cite: Liu, D., Liu, B., Liu, J., Zhang, H., Su, Y., Zhu, X., and Li, C.: Bands Selection for Multispectral Detection Mode of Lunar Mineralogical Spectrometer of China’s Chang’E-5 and Chang’E-6 Missions, Europlanet Science Congress 2024, Berlin, Germany, 8–13 Sep 2024, EPSC2024-349, https://doi.org/10.5194/epsc2024-349, 2024.
Ground Penetrating Radar (GPR) technology has been extensively applied in Chinese lunar exploration. The first attempt to survey the Moon’s subsurface using a GPR onboard a rover was made during the Chang’E-3 (CE-3) mission, which featured dual-frequency channels (G.Y. Fang, et al., 2014). The identical Lunar Penetrating Radar used in the CE-3 mission, was successfully deployed during the Chang’E-4 (CE-4) mission. It effectively explored the subsurface structure to a depth of ~ 40m within the South Pole-Aitken Basin, located on the farside of the moon (C.L. Li, et al., 2020).
Another remarkable design is the GPR of the Chang'e-5 (CE-5) mission. Because GPR for the CE-5 mission was mounted on the lander rather than on the rover, it was necessary to break the conventional design pattern. To address this challenge, an antenna-array radar was deployed,making the first application in the deep space mission. The array radar is named the Lunar Regolith Penetrating Radar (LRPR). The LRPR comprises a controller, a pair of transmitter and receiver, a distribution unit, a cable assembly, and an antenna array, which consists of 12 ultra-wideband time-domain antennas. As shown in Fig.1, these antennas are mounted asymmetrically around the drilling system as the bottom of the lander. Operating under a multiview/multistatic configuration, one antenna transmits while the other 11 antennas receive backscattered echoes during one measurement period(Y.X. Li, et al., 2019). Such configuration allows for the collection of 132 trace data. The complete measurement stage for the 12 transmitting antennas lasts ~18 minutes.
The Chinese CE-6 mission was successfully launched on May 3rd, 2024. The CE-6 landing zone has been selected to lie within the lunar farside South Pole–Aitken (SPA) basin in the southern part of the Apollo basin (150–158° W, 41–45° S), a site that provides access to a diversity of SPA material (see Fig.3). The CE-6 lander also carries the same radar instrument used in CE-5 mission, the LRPR. The primary objective of the LRPR is to investigate the interior structure of the local regolith and identify potential underground hazards that could pose risks to the drilling activity. Understanding the interior structures of lunar regolith is crucial for comprehending surface resulting from processes, such as impact cratering. Local stratigraphy provides the contextual information for interpreting the origin of samples collected from both the surface and the drilling core.
In this report, we will detail the signal calibration, data processing procedures of the array radar, and present the results obtained from the CE-5 LRPR. The CE-6 LRPR is expected to commence operations by the end of May. If successful, we will provide updates on the new results obtained. Given that the scheduled CE-6 landing site is situated within the most prominent SPA basin(see Fig.3), we are hopeful that the LRPR will unveil new discoveries.
Fig.1 Layout of the LRPR antennas around the drilling core onboard the CE-5 and CE-6 lander. (a) Side view and (b) bottom view of the antenna array. Antennas #1–#10 are aligned at the bottom of the CE-5 lander, while antennas #11 and #12 are installed separately.
Fig. 2 LRPR observations at the CE-5 drill-sampling site. (a) Variation of the drill bit force along the depths. The horizontal axis is force (N). The drilling system collected the rotation angle of a photoelectric encoder each second; then, this angle was converted to the distance of the drilling core movement to obtain the depth of the bit position. (b) LRPR radar image before drilling. The vertical axis is depth (cm), and zero-depth corresponds to the interface air/soil. The horizontal axis is the distance from the drill bit (cm). The red color represents high reflectivity (large electromagnetic contrast) and blue is low reflectivity (small electromagnetic contrast). (c) Radar image after drilling with the same processing method as that used in (b).
Fig.3 The landing site of CE-5 (a) and the schedule landing site of CE-6 (b). (a) The CE-5 probe landed on the lunar surface at 43.06 N, 51.92 W, a young and flat mare surface at the northeast Oceanus Procellarum. (b) The scheduled CE-6 landing zone is located in the interior of the SPA basin, along the southern rim of the Apollo basin.
References
- -Y. Fang, B. Zhou, Y.-C. Ji, Q.-Y. Zhang, S.-X. Shen, Y.-X. Li, H.-F. Guan, C.-J. Tang, Y.-Z. Gao, W. Lu, S.-B. Ye, H.-D. Han, J. Zheng, S.-Z. Wang, Lunar penetrating radar onboard the Chang’e-3 mission. Res. Astron. Astrophys. 14, 1607–1622, 2014.
- Li et al., “The Moon’s farside shallow subsurface structure unveiled by Chang’E-4 Lunar Penetrating Radar,” Sci Adv, vol. 6, no. 9, p. eaay6898, 2020.
- Li, W. Lu, G. Fang, B. Zhou, and S. Shen, “Performance verification of lunar regolith penetrating array radar of Chang’E-5 mission,” Adv. Space Res., vol. 63, pp. 2267–2278, Apr. 2019.
- Su et al., Hyperfine Structure of Regolith Unveiled by Chang’E-5 Lunar Regolith Penetrating Radar, IEEE Transactions on Geoscience and Remote Sensing, VOL. 60, 2022
How to cite: Su, Y., Li, C., Liu, J., Zhu, X., Liu, B., Liu, D., and Zhang, Z.: Antenna-Array Radar Applications in Chinese CE-5 and CE-6 Missions, Europlanet Science Congress 2024, Berlin, Germany, 8–13 Sep 2024, EPSC2024-239, https://doi.org/10.5194/epsc2024-239, 2024.
The use of Raman spectroscopy in planetary science has seen recent success with the deployment of the SHERLOC [1] and SuperCam [2] instruments on the Mars 2020 mission, and the development of instruments such as the ExoMars Raman Laser Spectrometer [3]. Raman spectroscopy is a useful technique for distinguishing mineral species and has the potential to identify organic chemicals, contributing to the search for extraterrestrial biomarkers. However, the limit of detection for the current set of Raman spectroscopy instruments on planetary missions may prevent the detection of trace concentrations of organic material present in the surface regolith or ice [4].
Fig. 1: Nanofabrication process flow for the creation of quartz nanopillars.
One method to improve the detection limit of Raman spectroscopy is to employ surface enhanced Raman spectroscopy (SERS). This technique exploits the interaction between incoming laser radiation, the analyte molecule, and hotspot regions associated with nanometer scale gaps in highly conductive materials such as silver and gold [5, 6]. Silver substrates typically provide high SERS enhancement factors [7], but suffer from degradation under storage conditions, with the enhancement factor reducing in a matter of days. Silver chloride provides one possible solution to this issue; silver chloride can be activated using the same laser wavelength as used for Raman spectroscopy (e.g. 532 nm), which creates regions of metallic silver which then contribute to SERS enhancement [8, 9].
We created geometrically ordered substrates using a nanofabrication process flow (fig. 1). Quartz glass wafers were patterned using electron beam lithography and then etched to provide an ordered pattern of nanopillars with diameter ~150 nm. These pillars were then coated with silver chloride via repeated immersion in solutions of silver nitrate (AgNO3) and sodium chloride (NaCl).
Fig. 2 SEM scan of hexagonally packed nanopillars, with geometric characterisation measurements
We present characterisation of the production process, using high aspect ratio nanofabrication techniques. Scanning electron microscopy (Fig 2, Fig 3) was used to characterise the geometry of the substrates. In addition, glass microscope slides which had not been altered with nanofabrication techniques were also coated with silver chloride, in order to evaluate the effect of the surface geometry.
Fig. 3 SEM scan of silver chloride crystals on a glass slide
We also present validation and analysis of the SERS enhancement effect from these substrates. Glycine, β-carotene and L-histidine were used as probe biomarker molecules. Raman spectra were taken using a 532nm benchtop spectrometer. Control measurements were performed using the same biomarkers on uncoated glass microscope slides.
[1] Bhartia, R., et al., Perseverance’s Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) Investigation. Space Science Reviews, 2021. 217(4): p. 58.
[2] Maurice, S., et al., The SuperCam instrument suite on the Mars 2020 rover: science objectives and mast-unit description. Space Science Reviews, 2021. 217: p. 1-108.
[3] Rull, F., et al., The Raman laser spectrometer for the ExoMars rover mission to Mars. Astrobiology, 2017. 17(6-7): p. 627-654.
[4] McKay, C.P., et al., The Icebreaker Life Mission to Mars: A Search for Biomolecular Evidence for Life. Astrobiology, 2013. 13(4): p. 334-353.
[5] Le Ru, E.C., et al., Surface Enhanced Raman Scattering Enhancement Factors: A Comprehensive Study. The Journal of Physical Chemistry C, 2007. 111(37): p. 13794-13803.
[6] Lee, S.J., et al., Surface-enhanced Raman spectroscopy and nanogeometry: The plasmonic origin of SERS. The Journal of Physical Chemistry C, 2007. 111(49): p. 17985-17988.
[7] Sharma, B., et al., SERS: Materials, applications, and the future. Materials Today, 2012. 15(1): p. 16-25.
[8] Volkan, M., D.L. Stokes, and T. Vo-Dinh, A sol–gel derived AgCl photochromic coating on glass for SERS chemical sensor application. Sensors and Actuators B: Chemical, 2005. 106(2): p. 660-667.
[9] Matikainen, A., et al., A solution to the fabrication and tarnishing problems of surface-enhanced Raman spectroscopy (SERS) fiber probes. Scientific Reports, 2015. 5(1): p. 8320.
How to cite: Bowden, D. and Sykulska-Lawrence, H.: Development of Surface Enhanced Raman Spectroscopy Substrates for Detection of Trace Biomarkers, Europlanet Science Congress 2024, Berlin, Germany, 8–13 Sep 2024, EPSC2024-1024, https://doi.org/10.5194/epsc2024-1024, 2024.
Purpose
This work presents the development and analysis of a SiO2 composite ionic liquid gel polymer electrolyte (SiO2-CILGPE)-based capacitor in air and carbon dioxide (CO2) atmospheres. The effectiveness of the proposed layer as a humidity-sensitive layer has been demonstrated in [1]. Its use as a humidity sensing layer not only stands out among other alternatives due to its sensing performance, but also because of its cost-effectiveness, scalability, and non-toxicity. In this realm, this study exhibits a brief comparison of the impedance characteristics of the proposed device under air and CO2 conditions, aiming to examine a first insight into the impact of CO2 onits electrical behaviour to evaluate its potential use as a relative humidity sensor for planetary research applications, such the ones carried out in Mars for habitability studies.
Methodology
Figure 1 illustrates the fabrication process of the SiO2 CILGPE. The fabrication starts by dissolving the host polymers (HPs) in deionised water at 70 ºC. Then, a blend of CH₃COONH₄ and 1-Butyl-3-methylimidazolium bromide is incorporated and stirred at 70 ºC. Afterwards, SiO₂ nanoparticles are embedded in the resultant ILGPE using an ultrasound bath until a homogenous mixture is achieved. Finally, the resulting electrolyte is deposited onto the active electrode area using drop-casting and subsequently cured, forming a layer with a thickness of around 600 μm and length and width of 0.4 mm and 1mm, respectively.
The humidity sensing performance of the SiO2 CILGPE-based capacitor was evaluated using the electrochemical impedance spectroscopy (EIS) technique under different humidity conditions at atmospheric pressure. The impedimetric response has been obtained using the impedance module values, while the capacitance response has been calculated using Equation 1:
C = -𝑍′′/( 2𝜋 𝑓𝑍2) (Eq. 1)
Where 𝑍 and 𝑍′′ are the module and imaginary part of the impedance, respectively.
Furthermore, EIS measurements under air and CO2 conditions at different pressures have been carried out and compared to evaluate its behaviour under a CO2 atmosphere. This evaluation starts with air evacuation until a partial vacuum, reducing the concentration of air. This first part of the process provides information about the impact of pressure variations on the electrical behaviour of the SiO2 CILGPE-based capacitor under air conditions. Once 0.1 mbar is reached, CO2 is injected in a controlled and gradual manner. This second step stimulates an increase in the internal pressure of the chamber and allows a preliminary analysis of how the quantity of CO2 can impact the impedimetric characteristics of the device. This methodology enables the characterisation of the SiO2-CILGPE-based capacitor under different conditions of pressure and gas composition, thereby providing initial insights into how the presence of different gases affects its performance. The exhibited EIS measurements can be fitted using the equivalent circuit (EC) displayed in Figure 4. The analysis of EIS data from ECs could allow a first insight into the understanding of the impact of CO2 on the sensing mechanism and performance of the SiO2 CILGPE-based capacitor.
Results
Figure 2 illustrates the obtained Z and capacitance humidity sensing responses. As can be noticed, the SiO2 CILGPE-based capacitor reveals changes in two parameters, increasing its reliability compared to other relative humidity sensors in the literature and offering more information that could facilitate the calibration process.
Following the analysis of the EIS data, Figure 3 compares the obtained impedance module, phase, and capacitance spectra under air and CO2 atmospheres. It is noticeable that the curves of the three parameters of the SiO2 CILGPE-based capacitor exhibit the same trend under the presence of both gases, thereby suggesting the SiO2 CILGPE layer could work similarly under air and CO2.
Nevertheless, the characterised parameters reveal opposite shifts in response to pressure variations. Firstly, under an air atmosphere, it can be noticed that a reduction in the pressure implies an increase in the impedance module and a decrease in the capacitance. This behaviour could be ascribed to a reduction of the water vapour molecules since reducing the pressure inside the measurement chamber also implies a reduction in the partial pressure of all gases, including water vapour [2]. Reducing the water molecules promotes a decrease in the number of charge carriers within the humidity-sensitive layer and, hence, an increase in the impedance and a decrease in the capacitance. Conversely, under a CO2 atmosphere, the SiO2 CILGPE-based capacitor depicts an increase in the impedance module values and a reduction in the capacitance when increasing the pressure. This finding might be attributed to the injection of CO2 into the vacuumed chamber. One possible explanation for such phenomena is that introducing CO2 into the chamber increases the pressure, thereby could reduce the water vapour concentration relative to the total gas, promoting a decrease in the relative humidity. Consequently, the obtained impedance spectra suggest that the SiO2 CILGPE-based capacitor could possess the same response to relative humidity variations under the presence of air and CO2. Further research should focus on investigating and analysing the impact of CO2 presence under different relative humidity levels.
Conclusions
EIS measurements show that, under air and CO2 conditions, the SiO2 CILGPE-based capacitor exhibits similar impedance, phase, and capacitance curve trends, thereby suggesting the SiO2 CILGPE layer could operate following similar electrical behaviours under CO2. Additionally, this comparison shows that a reduction in the relative humidity could imply the same response under air and CO2 atmospheres. Therefore, it might suggest that CO2 does not alter the dominant sensing mechanism.
Consequently, this work provides first insights into the possible potential of a non-toxic, cost-effective alternative based on a SiO2 CILGPE as a sensing layer for humidity sensing in CO2 atmospheres.
Acknowledgements
This work has been supported by the projects TED2021-131552B-C22 and PID2021-126719OB-C42.
References
- [1] Cedeño Mata, M.; Orpella, A.; Dominguez-Pumar, M.; Bermejo, S. Boosting the Sensitivity and Hysteresis of a Gel Polymer Electrolyte by Embedding SiO2 Nanoparticles and PVP for Humidity Applications. Gels 2024, 10, 50, doi:10.3390/gels10010050.
- [2] McIntosh, D. H. and A. S. Thom, Essentials of Meteorology, 1978, Wykeham Publications.
How to cite: Cedeño, M., Palomas, A., Manyosa, X., Coloma, A., Domínguez-Pumar, M., and Bermejo, S.: Electrochemical impedance spectroscopy analysis of a SiO2 submicron-particles-based relative humidity sensor for planetary research applications, Europlanet Science Congress 2024, Berlin, Germany, 8–13 Sep 2024, EPSC2024-936, https://doi.org/10.5194/epsc2024-936, 2024.
Introduction: Kelvin-Helmholtz instability (KHI) is considered one of the main processes of transferring solar wind energy, momentum and plasma inside magnetosphere. At the Earth, KHIs are observable in the form of waves (KHWs) within the magnetopause region between the anti-Sunward magnetosheath and the relatively stagnant magnetosphere.
Over the past few decades, several missions (THEMIS, Cluster, MMS) have contributed significantly to our understanding of KHI. In this sense, it is well-known that (i) KHIs are a common phenomenon [1,2], (ii) KHIs can be generated under different IMF conditions [2], (iii) KHIs can lead to rolled-up vortices [3], (iv) KHVs drive the onset of magnetic reconnection (Vortex-Induced Reconnection) leading to development of Tearing Mode instability [4] and formation of magnetic islands, evolving into flux ropes [5], and (v) in the late nonlinear phase, vortex merging and secondary KHIs development in a wider latitudinal range [6]. In addition, [7] found that KHWs occur at the (flank) magnetopause for approximately 19% of that time. The occurrence of these waves is influenced by factors such as solar wind speed, Alfven Mach number and number density, and is mostly independent on the IMF magnitude. These conditions can be easily met when a perturbation propagates within the interplanetary medium, such as during the occurrence of a coronal mass ejection.
Investigating the conditions under which KH and TM instabilities occur in the Earth environment, using simultaneous multipoint in-situ measurements and MHD simulations, is intriguing because it could provide insights into the flow dynamic nature at the magnetopause mixing layer. In this sense, we analyzed data from THEMIS and Cluster spacecraft considering two "target" Space Weather events occurred on 21 June 2015 (Case-1) and on 6 September 2017 (Case-2).
The Model: Our analysis utilized a 2D MHD model [8] which describes the flow dynamics of the magnetopause mixing layer in a fluid limit. The simulation domain consists of a rectangular region in (x,y)-plane. On the local Cartesian grid, it is defined as follows: (i) neglecting the realistic curvature; (ii) considering the x-coordinate pointing to the direction along the velocity of the incident magnetosheath flow; (iii) assuming the y-coordinate in the direction downward to the Earth’s center (from the magnetosheath to the magnetosphere) and (iv) ensuring a right-handed coordinate system with the z-coordinate.
The used approach is flexible enough to represent any position on the dayside magnetopause.
Results: In Case-1, we used our MHD model to interpret observational data and to investigate the potential development of KHVs on the dawn flank magnetopause as a consequence of the arrival of the ICME. Using THEMIS-E data, we found that at the magnetopause nose no rolled-up KHVs developed due to the absence of a shear between the two fluids. On the contrary, structures similar to magnetic islands appeared in By component very fast and vanished for 10 computational seconds. At the dawn flank magnetopause, the analysis of Cluster data revealed high flow and low magnetic shear between the magnetosheath and the magnetosphere. According to theoretical predictions, these conditions favour the onset of KHI. MHD simulations confirmed these considerations, finding that KHVs developed very rapidly and persisted up to 20 computational seconds (Figure 1), reaching almost MHD instability steady state. Regarding the TM instability, the MHD simulations revealed only an early development of magnetic islands (Figure 2), that persisted for half of the time of the KHVs evolution. In a global scale, these results indicate that vortices become unstable far away from the subsolar point in the direction of high flow shear. 
Figure 1. Case 1. Evolution of KH instabilities in density at the dawnward flank of the magnetopause, from 1 to 30 seconds. Input data obtained from the Cluster-C4 measurements. The dimensionless boundary conditions from the magnetosphere side and magnetosheath side are taken everywhere to be identical: BMSPx=-1.24, BMSHx=1.0, BMSPy=0.4, BMSHy=1, ρMSP =0.2, ρMSH=1, Re= 250 and Rm= 1 000, MA= 0.2. Blue region represents the magnetosphere whilst red region represents the magnetosheath.
Figure 2. Case 1. Evolution of TM instabilities in By at the dawnward flank of the magnetopause. Same of Figure 1.
In Case-2, using THEMIS-E data, we did not find any evidence of KHI owing to the extremely low flow and high magnetic shear. On the contrary, adopting Cluster-C4 data, MHD simulations revealed that the fast development of disturbances but no signatures of KHVs were visible. Additionally, magnetic islands appeared very fast as a result of high shear in the components of the magnetic field but rapidly vanished.
References:
[1] Hasegawa, H., et al. (2004). Nature, 430, 755–758.
[2] Hasegawa, H., et al. (2006). JGR, 111, A09203.
[3] Lin, D., et al. (2014). JGR, 119, 7485–7494.
[4] Chen, Q., et al. (1997). JGR, 102, 151–162
[5] Eriksson, S., et al. (2009). JGR, 114, A00C17.
[6] Sisti, M., et al. (2019). Geophysical Research Letters 46, 11,597–11,605
[7] Kavosi, S. and Raeder, J. (2015). Nature Communications, 6, 7019.
[8] Ivanovski, S., et al. (2011). Journal of Theoretical and Applied Mechanics, 41, 31–42
How to cite: Biasiotti, L., Ivanovski, S., Calderone, L., Jerse, G., Laurenza, M., Del Moro, D., Longo, F., Plainaki, C., Marcucci, M. F., Milillo, A., Molinaro, M., and Feruglio, C.: Kelvin-Helmholtz and tearing mode instabilities at the magnetopause during space weather events, Europlanet Science Congress 2024, Berlin, Germany, 8–13 Sep 2024, EPSC2024-130, https://doi.org/10.5194/epsc2024-130, 2024.
1 Introduction
The upcoming Dragonfly rotorcraft mission by NASA is planned to be sent to the surface of Saturn’s moon Titan [1]. As part of the Dragonfly Entry Aerosciences Measurements (DrEAM) suite [2], the Dragonfly entry capsule will include a subsystem called COmbined Sensor System for Titan Atmosphere (COSSTA), developed by the Supersonic and Hypersonic Technologies Department of the DLR Institute of Aerodynamics and Flow Technology in cooperation with NASA (T. Thiele, private communication, 2023). One of the sensors of COSSTA is a pressure sensor developed by the Finnish Meteorological Institute (FMI). The sensor, named COSSTA-PL, is dedicated to measuring the static pressure on the entry capsule backshell.
The design of COSSTA-PL relies heavily on the heritage of FMI’s pressure sensors previously developed for Mars landers, such as the Curiosity rover of Mars Science Laboratory (MSL) and the Perseverance rover of Mars 2020. The optimal measurement range of COSSTA-PL is close to the typical surface pressure of Mars, namely up to about 10 hPa, with a capability to measure pressures up to 20 hPa.
2 Sensor description
COSSTA-PL is a miniature pressure device directly based on MEDA PS [3], the pressure sensor of the Perseverance rover. At its core are the Barocap® sensor head and transducer technologies developed by Vaisala. Barocap is a micromachined silicon pressure sensor based on capacitive sensing. COSSTA-PL contains two Barocap types, NGM and RSP2M, which are both optimized for the low-pressure range.
COSSTA-PL consists of two transducers, each working independently of the other. Transducer 1 contains two NGM type Barocap sensor heads while transducer 2 has two RSP2M type Barocaps. Both transducers also include two Thermocap temperature sensor heads and constant reference capacitors for data processing purposes. The main distinction from MEDA PS is that COSSTA-PL includes two PT1000 temperature sensors directly attached to the NGM Barocap sensor heads. As the Barocap readings are sensitive to temperature, the purpose of the PT1000 sensors is to provide the accurate temperature readings of the sensor heads.
The Barocap sensor heads and transducer electronics are enclosed by airtight Faraday shields made of PCB material (see Fig. 1). A small tube exits the shield, connecting the sensors with the surrounding pressure. The dimensions are 62×50×17 mm without the tube.
Figure 1. Prorotype model of COSSTA-PL
3 Testing and calibration
As the sensor may be exposed to extremely cold environment during the long cruise, initial testing of a prototype model was performed at DLR in Cologne to investigate how the sensor endures temperatures down to -150 °C. These were followed by further testing at FMI, focusing on verifying the operation of the ASIC in extremely low temperatures.
Calibration is planned to be performed mainly at FMI in the 0 to 20 hPa pressure range and -70 °C to +55 °C temperature range. Calibration down to -150 °C (TBC) is continued at the COSSTA level. The calibration will include measurements in both stable and changing pressure, as well as in changing temperature. Calibration checks at the higher level after integration and during the cruise phase are also planned.
References
[1] Lorenz, R. D. et al. (2018). Dragonfly: A Rotorcraft Lander Concept for Scientific Exploration at Titan, Johns Hopkins APL Technical Digest 34(3), pp. 374-387.
[2] Brandis, A. et al. (2022). Summary of Dragonfly’s Aerothermal Design and DrEAM Instrumentation Suite, 9th International Workshop on Radiation of High Temperature Gases for Space Missions, 12 – 16 Sep 2022, Santa Maria, Azores, Portugal.
[3] Jaakonaho, I. et al. (2023). Pressure sensor for the Mars 2020 Perseverance rover, Planetary and Space Science 239, 105815, https://doi.org/10.1016/j.pss.2023.105815.
How to cite: Jaakonaho, I., Hieta, M., Genzer, M., Polkko, J., Thiele, T., and Harri, A.-M.: Low-pressure sensor for Titan entry investigations of the Dragonfly mission, Europlanet Science Congress 2024, Berlin, Germany, 8–13 Sep 2024, EPSC2024-392, https://doi.org/10.5194/epsc2024-392, 2024.
The Japanese Mars Moon eXploration (MMX) mission will explore the two Moons of Mars: Phobos and Deimos [1]. The Japanese probe will first orbit Phobos before landing in order to conduct a sample collection before proceeding to orbit Deimos and then return to Earth. The Centre National d’Etudes Spatiales (CNES) and the Deutsches zentrum für Luft- und Raumfarht (DLR) have jointly developed a small rover called IDEFIX (Fig 1) that will leave the Earth in 2026 with the Japanese MMX mission. It will be deployed onto the surface of Phobos to conduct preliminary ground analyses, ensuring a safer landing for the main MMX spacecraft [2]. The IDEFIX rover has two cameras near the wheels called WheelCams [3], which are directed at the ground. Thanks to these, IDEFIX will be able to capture close-up images of the ground, providing information regarding the size, distribution and morphology of regolith particles [4]. By studying the interactions between the regolith and the rover wheels, other important information can be obtained such as the frictional and cohesive properties of the ground.
Figure 1: The IDEFIX rover. The positions of the two WheelCams are indicated (image: CNES)
The work presented here focuses on using the WheelCam images to measure the local topography of the ground underneath the rover, specifically the shape of the trench left by the rover’s wheels after rolling. The images are generated using the MMX rover-wheel test bed at ISAE-SUPAERO that is instrumented with cameras similar to the MMX rover WheelCams [5]. An algorithm based on a Structure from Motion (SFM) method was developed to reconstruct the shape of the trench. Due to the non-overlapping field of views of the two WheelCams [3], only one camera is used. Consecutives images captured by one single camera while the rover is in motion enable the creation of a 3D model including the ground, the objects passing nearby the rover and the trench left by the wheel.
Below (Fig.2), an example of a 3D model generated by the SFM algorithm is presented. In this example, the wheel is driving on sand and the bumps left by the wheels are clearly visible both in the images and in the reconstruction. The reference point is set to be the position of the first camera.
Figure 2: 3D model of the trench left by the wheel rolling on sand
In order to validate the SFM algorithm and the 3D model obtained, objects with a known shape and size have also been placed in the field of view and modeled by the algorithm. These tests also allow us to evaluate the performance of the SFM algorithm under different conditions (varying wheel velocities, lighting conditions, regolith types....). In addition to verifying the correct retrieval of the objects’ size and shape, a second method of validation was also applied. The SFM method gives an estimation of the position of the camera at each frame, which can be seen in red in the point cloud Figure 3. The ISAE-SUPAERO rover-wheel testbed has laser distance sensors that give the precise position of the camera when each picture is taken. Thus, the laser measurements can be used as ground truth data and compared to the estimated position of the camera from the model. This comparison is shown in Figure 4.
Figure 3: (left) WheelCams Perspectives. An object with a known size and shape is covered by a speckle and placed on a flat speckled surface. (right) 3D point cloud of the scene with the successive camera positions (red)
Figure 4: Comparison of the linear velocity estimated from the SFM algorithm (red) to the laser distance sensor ground truth measurement (black dashed)
This work demonstrates that it is possible to reconstruct the shape of the ground, and more specifically the morphology of the trench left by the wheel, using the IDEFIX WheelCam images. This will allow us to make measurements of the track depth, and thus the rover sinkage in addition to providing measurements of the angle of repose if the trench walls collapse. Moreover, an estimation of the consecutive camera positions can be obtained, which enables the linear velocity of the rover to be computed. This information will be valuable to help estimate the slippage of the wheels on Phobos and thus assess the performance of the rover’s locomotion.
Acknowledgements
This work has received funding from CNES, in the context of the MMX rover mission.
References
[1] Kuramoto, K., Kawakatsu, Y., Fujimoto, M., Araya, A., Barucci, M. A., Genda, H., ... & Yokota, S. (2022). Martian moons exploration MMX: sample return mission to Phobos elucidating formation processes of habitable planets. Earth, Planets and Space, 74(1), 12.
[2] MICHEL, Patrick, ULAMEC, Stephan, BÖTTGER, Ute, et al. The MMX rover: performing in situ surface investigations on Phobos. earth, planets and space, 2022, vol. 74, p. 1-14.
[3] Murdoch et al. The science goals of the IDEFIX rover WheelCams, EPSC 2024
[4] Robin C. Q., Duchêne A., Murdoch N., et al. Mechanical properties of rubble pile asteroids: insights from a morphological analysis of surface boulders. Nature Communications, accepted (2024)
[5] Passoni, L., et al. "A Single-Wheel Testbed for Regolith Science Studies." Lunar and Planetary Science Conference. No. 2548. 2021.
How to cite: Amsili, A., Murdoch, N., and Vivet, D.: 3D reconstruction of MMX rover tracks using WheelCam images, Europlanet Science Congress 2024, Berlin, Germany, 8–13 Sep 2024, EPSC2024-407, https://doi.org/10.5194/epsc2024-407, 2024.
Mass spectrometry plays an important role in advancing space exploration. It provides unique insights into the composition of space dust, micrometeorites, and particles from distant large objects and can be used both in orbit and on the surface of an asteroid.
The space instrument HANKA (Hmotnostní ANalyzér pro Kosmické Aplikace) is a high-resolution mass spectrometer based on an electrostatic ion trap, which is a principal component of commercial instruments[1] established in biology and medicine research, the so-called Orbitrap™, and the space CosmOrbitrap prototype (developed in LPC2E Orleans[2]). HANKA can take this new technology into space, combining a compact CubeSat space version of this high-resolution ion trap mass analyzer with a velocity/charge detector and hypervelocity impact ionization source.
Figure 1: HANKA – CubeSat space version (a), laboratory prototype (b), and preliminary data from EI source(c)[3]
Based on the results obtained from the laboratory prototype, a miniature CubeSat version of the high-resolution mass spectrometer for in-situ exploration in space will be constructed. The proposed parameters of the CubeSat module HANKA are:
> Resolution: up to 50 000 at m/z 200
> Mass Range: 2 – 3000 m/z
> Dimension: 200x200x100 mm (4U)
> Weight: < 6kg
> Power: 5-10 W
Acknowledgements: This work was supported by the Czech Science Foundation (grant No. 21-11931J)
References
[1] Makarov, A.; Anal. Chem. 2000, 72, 1156–1162.
[2] Briois C., Thissen R., Thirkell L., et al.; Planet Space Sci. 2016, 131, 33‐45.
[3] Zymak Y., Zabka J., Polášek M., et al.; al.; Aerospace 2023, 10(6), 522.
How to cite: Maleckova, M., Žabka, J., Zymak, Y., Polášek, M., Cherville, B., Jašík, J., Spesyvyi, A., Lacko, M., Kashkoul, M., Sanderink, A., Nezvedová, M., Sixtová, N., Charvát, A., and Abel, B.: HANKA> CubeSat Space Dust Analyser, Europlanet Science Congress 2024, Berlin, Germany, 8–13 Sep 2024, EPSC2024-876, https://doi.org/10.5194/epsc2024-876, 2024.