GI3.2

MEDA HS is the relative humidity sensor on the Mars 2020 Perseverance rover provided by the Finnish Meteorological Institute (FMI). The sensor is a part of Mars Environmental Dynamic Analyzer (MEDA), a suite of environmental sensors provided by Centro de Astrobiología in Madrid, Spain. MEDA HS, along with METEO-H in ExoMars 2022 surface platform, is a successor of REMS-H on board Curiosity.

Calibration of relative humidity (RH) instruments for Mars missions is challenging due to the range of RH (from 0 to close to 100%) and temperature conditions (from about -90 ºC to + 22 ºC) that need to be simulated in the lab. Thermal gradients in different parts of the system need to be well known and controlled to ensure reliable reference RH readings. For MEDA HS the calibration tests have been performed for different models of MEDA HS in three Martian humidity simulator laboratories: FMI laboratory, Michigan Mars Environmental Chamber (MMEC) and DLR PASLAB (Planetary Analog Simulation Laboratory).

MEDA HS flight model was tested at FMI together with flight spare and ground reference models in low pressure dry CO₂ gas from +22ºC to -70ºC and in saturation conditions from -40ºC down to -70ºC. Further, the MEDA HS flight model final calibration is complemented by calibration data transferred from an identical ground reference model which has gone through rigorous testing also after the flight model delivery. During the test campaign at DLR PASLAB that started in Autumn 2020, MEDA HS has been calibrated over the full relative humidity scale between -70 to -40ºC in CO₂ in the pressure ranges from 5.5 to 9.5 hPa, representative of Martian surface atmospheric pressure. The results can be extrapolated to higher and lower temperatures.

In this presentation the final flight calibration and performance of the MEDA HS will be presented together with first results expected from the surface of Mars by the Perseverance rover.

How to cite: Hieta, M., Genzer, M., Polkko, J., Jaakonaho, I., Lorek, A., Garland, S., de Vera, J.-P., Martinez, G., Fischer, E., Rodríguez Manfredi, J. A., Tamppari, L., and de la Torre Juarez, M.: Calibration and first results of relative humidity sensor MEDA HS on board M2020 rover, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12130, https://doi.org/10.5194/egusphere-egu21-12130, 2021.

One of the unique candidates to explore the evolution of physical surface processes on the Moon is Tycho, a dark haloed impact crater representing well-preserved bright ray pattern and intact crater morphology. Sampling of the central peak in such complex crater formation proves significant in terms of unraveling intriguing science of the lunar interior. With the current state-of-the-art radar technology, it is possible to evaluate the response of the geologic features constrained in the near surface and subsurface regolith environments. This can be achieved by modelling the dielectric constant of media, which is a physical parameter crucial for furthering our knowledge about the distribution of materials within different stratigraphic layers at multiple depths. Here, we used the applicability of Mini-RF S-band data augmented with a deep learning based inversion model to retrieve the dielectric variations over the central peak of the Tycho crater. A striking observation is made in certain regions of the central peak, wherein we observe anomalously high dielectric constant, not at all differentiated in the hyperspectral image and first Stokes parameter image, which usually is a representation of retrieved backscatter of the target. The results are also supported by comparing the variations in the scattering mechanisms. We found those particular regions to be associated with high degree of depolarization, thereby attributing to the presence of cm- to m- scale scatterers buried within a low dielectric layer that are not big enough to produce even-bounce geometry for the radar wave. Moreover, we also observe high rock concentration in the central peak slopes from DIVINER data and NAC images, indicating the exposure of clasts ranging in size from 10 meter to 100s of meter. Furthermore, from surface temperature data, these distinctive outcrops sense warmer temperature at night than the surrounding, which suggests the existence of thermal skin depth in such vicinities. Interestingly, we are able to quantify the pessimistic dielectric constant limit of the large boulder in the middle of the central peak, observable at the Mini-RF radar wavelength, as 4.54 + j0.077. Compared to the expected dielectric constant of rocks, this value is lowered significantly. One probable reason could be the emergence of small radar shadows due to the rugged surface of the boulder on the radar illuminated portion. From our analysis, we showcase the anomalous dielectric variability of Tycho central peak, thereby providing new insights into the evolution of the impact cratering process that could be important for both science and necessary for framing human or robotic exploration strategies.  

How to cite: Shukla, S. and Patterson, G. W.: Anomalous Dielectric Variability in the central peak of Tycho crater on the Moon: New insights from Mini-RF S-band Observations, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16552, https://doi.org/10.5194/egusphere-egu21-16552, 2021.

The search for life is one of the key topics in modern space science. The JUICE mission of the European Space Agency ESA will investigate Jupiter and its icy moons Ganymede, Callisto and Europa, with Europa being an example of a potentially habitable world around a giant gas planet. The Particle and Environment Package, PEP, on board of the JUICE spacecraft will investigate Jupiter’s icy moons and their environment. The Neutral gas and Ion Mass spectrometer NIM will investigate the icy moon’s exospheres to investigate their formation and the interaction processes of the exospheres with the moons’ surface and Jupiter’s strong magnetic field. It will enhance our understanding of the processes involved in the interactions of ion bombardment on the icy moons' surfaces. From these measurements, we will derive the moons’ surface composition and their formation processes.

NIM is a time-of-flight mass spectrometer with two particle entrances: an open-source entrance to measure neutral particles and ions directly and a close source entrance where neutral particles get thermalized before entering the sensor’s ionization region. This allows detecting of particles with high speeds. NIM has a specially designed ion storage source and an ion-mirror to double the flight distance of the produced ions by keeping the sensor at a minimal size.

In this contribution, we show calibration results of the NIM flight spare instrument on one hand operated with laboratory and on the other operated with flight electronics. We demonstrate the performance of NIMs ion-source, verify the performance of the closed-source antechamber. NIM has a demonstrated mass resolution of m/Δm 800.

How to cite: Föhn, M., Tulej, M., Galli, A., Vorburger, A. H., Lasi, D., Riedo, A., Wurz, P., Brandt, P., and Barabash, S.: Initial Calibration Results of the NIM Flight Spare Mass spectrometer for Exploration of Jupiter’s Icy Moons Exospheres, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3821, https://doi.org/10.5194/egusphere-egu21-3821, 2021.

The exploration of Callisto is part of the extensive interest in the icy moons characterization. Indeed, Callisto is the Galilean moon with the best-preserved records of the Jovian system formation. Led by the National Space Science Center (NSSC), Chinese Academy of Science (CAS), the planned Gan De mission aims to send an orbiter around Callisto in order to characterize its surface and interior. Potential orbit configurations are currently under study for the Gan De mission proposal.

As part of a global characterization of Callisto, its gravity field can be inferred using radio tracking data from an orbiter. Mission characteristics such as orbit type, Earth beta angle and solar elongation will have a direct influence on the recoverability of its gravity field parameters. In this study, we will analyse this influence from closed-loop simulations using the planetary extension of the Bernese GNSS Softwareai.

A number of reference orbits with different orbital characteristics will be selected for the Gan De mission and, using an extended force model, will be propagated from different starting dates and different initial Earth beta angles. Realistic Doppler tracking data (2-way X-band Doppler range rate) will be simulated as measurements from ground stations, with a dedicated noise model. These observations will then be used to reconstruct the orbit along with dynamical parameters. The focus of this presentation will be on the quality of the retrieved gravity field parameters and tidal Love number k2.

How to cite: Desprats, W., Arnold, D., Blanc, M., Jäggi, A., Li, M., Li, L., and Witasse, O.: Recoverability of Callisto gravity field influenced by orbiter mission characteristics, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9959, https://doi.org/10.5194/egusphere-egu21-9959, 2021.

How to cite: Johansson, F. L., Eriksson, A., Gilet, N., Henri, P., Wattieaux, G., Taylor, M., Imhof, C., and Cipriani, F.: A charging model for the Rosetta spacecraft, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9508, https://doi.org/10.5194/egusphere-egu21-9508, 2021.

The in situ characterization of space plasmas requires an instrument suite for the measurement of the magnetic and electric fields and waves and of the plasma populations, with the field instruments typically being mounted on booms. This can be a tall order, especially for small planetary science missions, so that one has to seek simplifications. In the context of the Comet Interceptor mission, we have designed a combined sensor that consists of a hollow spherical Langmuir probe that harbors a fluxgate magnetometer at its center. Special precautions have been taken to minimize the possible interference between both, while at the same time being very lightweight. An engineering model has been built and is tested and characterized in detail. Such a combined sensor, together with a companion Langmuir probe, provides data regarding magnetic and electric fields and waves, total ion and electron densities and electron temperature, as well as the ambient nanodust population. It can form the core of an in situ plasma characterization package and offers reference data for the other sensors, such as magnetic field direction, spacecraft potential and total plasma density at high cadence.

How to cite: De Keyser, J., Ranvier, S., Maes, J., Pawlak, J., Neefs, E., Dhooghe, F., Auster, U., Chares, B., Edberg, N., Fredriksson, J., Eriksson, A., Henri, P., Le Duff, O., and Peterson, J.: A combined Langmuir Probe – fluxgate magnetometer sensor design for Comet Interceptor, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7197, https://doi.org/10.5194/egusphere-egu21-7197, 2021.

The energetic neutral atom detection instrument IMAP-Lo is part of the scientific payload of the upcoming Interstellar Mapping and Acceleration Probe (IMAP) mission by NASA and is designed to analyse interstellar neutral and heliospheric Energetic Neutral Atom fluxes and their composition for energies from 1000 eV down to 10 eV. IMAP is dedicated to extend our knowledge of the local interstellar medium (LISM) and its interaction with the solar magnetic field and the heliosphere. Most importantly, H, He, O and Ne ENAs will be analysed.

Calibration and testing of IMAP-Lo is planned in MEFISTO, a unique laboratory test facility for ion and neutral particle instruments at the University of Bern, which can provide the required neutral atom beams. In MEFISTO we have a microwave-induced plasma ion source for beam energies up to 100 keV/q. The ion beam can be converted to a neutral beam in the energy range 10 eV – 3 keV with a removable ion beam neutralizer with decelerating the ion beam first and subsequent neutralisation via surface reflection. It comes with an estimated beam energy reduction of 15 % and energy-dependent transmission. The neutral beam flux into the test chamber therefore depends on the ion beam energy, intensity and species. To improve the calibration process for ENA space instruments such as IMAP-Lo, it is important to measure the neutral beam flux and energy in the test facility.

The Absolute Beam Monitor (ABM) is a novel laboratory device developed for absolute neutral particle flux measurements and energy determination of neutral atom beams. The ABM takes advantage of secondary electron emission during surface scattering of incident neutral atoms off a highly polished tungsten plate. The effective rate of neutrals is inferred from detecting secondary electrons and reflected atoms in two electron multipliers as well as its coincidence signal rate. Time difference of the two signals yields the neutrals energy. To date, the ABM is the only device to measure absolute fluxes of neutral atoms in this energy range.

Measurements of the neutral beam source in MEFISTO have been performed for several species using the ABM to determine the relation between the effective neutral atom flux and the primary ion beam current at the charge conversion surface, as well as the neutral beam energy, for ion energies from 1000 eV down to 10 eV.

How to cite: Gasser, J., Galli, A., and Wurz, P.: Calibration of a neutral particle beam source with the novel Absolute Beam Monitor, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-956, https://doi.org/10.5194/egusphere-egu21-956, 2021.

The Sweeping Langmuir Probe (SLP) instrument on board the Pico-Satellite for Atmospheric and Space Science Observations (PICASSO) has been developed at the Royal Belgian Institute for Space Aeronomy.  PICASSO, an ESA in-orbit demonstrator launched in September 2020, is a triple unit CubeSat orbiting at about 540 km altitude with 97 degrees inclination. The SLP instrument includes four independent cylindrical probes that are used to measure the plasma density and electron temperature as well as the floating potential of the spacecraft. Along the orbit of PICASSO the plasma density is expected to fluctuate over a wide range, from about 1e8/m³ at high latitude up to more than 1e12/m³ at low/mid latitude. SLP can measure plasma density from 1e8/m³ to 1e13/m³. The electron temperature is expected to lie between approximately 1000 K and 10.000 K. Given the high inclination of the orbit, SLP will allow a global monitoring of the ionosphere. Using the traditional sweeping mode, the maximum spatial resolution is of the order of a few hundred meters for the plasma density, electron temperature and spacecraft potential. With the fixed-bias mode, the electron density can be measured with a spatial resolution of about 1.5 m. The main goals are to study the ionosphere-plasmasphere coupling, the subauroral ionosphere and corresponding magnetospheric features together with auroral structures and polar caps, by combining SLP data with other complementary data sources (space- or ground-based instruments). The first results from SLP will be presented.

How to cite: Ranvier, S., De Keyser, J., and Lebreton, J.-P.: First results from the Sweeping Langmuir Probe (SLP) instrument on board PICASSO, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9915, https://doi.org/10.5194/egusphere-egu21-9915, 2021.

The ESA/JAXA mission BepiColombo, launched on 20 October 2018 is in cruise towards Mercury and will arrive at Mercury in 2025 to investigate its surface, interior structure and magnetosphere. The Mercury Orbiter Radio-science Experiment (MORE) onboard the Mercury Planetary Orbiter (MPO) aims at determining the gravity field, the rotational state and librations of the planet, using precise tracking of the spacecraft during its orbital phase around Mercury. Range and range-rate measurements collected during the cruise phase will be used to test the theory of general relativity starting in March 2021. The MORE experiment exploits two-way multifrequency microwave links from ESA and NASA: two downlinks in X- and Ka-band coherent with the X-band uplink and one Ka-band downlink coherent with the Ka-band uplink. The range-rate and range measurements accurately BepiColombo’s line-of-sight velocity and the round-trip light-time of the signal, respectively. The calibration of the dispersive plasma noise component through the combination of the X/X, X/Ka and Ka/Ka links and the use of water vapor radiometers to correct for the path delay due to Earth’s troposphere will result in an accuracy of ~3 µm/sec (at 1000-s integration time) on the Doppler and centimeter-level range accuracies. We report on the analysis of dedicated tests executed on range and Doppler data collected by ESA and NASA stations at X and Ka-band. The comparison of the observed noise with the predictions shows results exceeding the expectations. In particular, the 24 Mcps pseudo-noise modulation of the Ka-band carrier, enabled by MORE’s KaT transponder built by Thales Alenia Space Italia, provided two-way range measurements accurate to ~3 cm with just 4 s integration time, at a distance of 0.7 AU, September 2021, and 1.3 AU, November 2021. Under favorable weather conditions, the range rate has shown an accuracy of 25 µm/s at 10 s integration time, in line with the expected end-to-end performance. Under unfavorable weather conditions the performance was slightly over the requirements. We must remark that calibrations from water vapor radiometers were not available during these tests and only GNSS calibration were applied.

How to cite: Cappuccio, P., Iess, L., Durante, D., di Stefano, I., Racioppa, P., and Asmar, S.: Inflight performance of the state-of-the-art BepiColombo MORE radio-tracking system, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15954, https://doi.org/10.5194/egusphere-egu21-15954, 2021.

Minimum variance distortionless projection, the so-called Capon method, serves as a powerful and robust data analysis tool when working on various kinds of ill-posed inverse problems. The method has not only successfully been applied to multipoint wave and turbulence studies in the context of seismics and space plasma physics, but it is also currently being considered as a technique to perform the multipole expansion of planetary magnetic fields from a limited data set, such as Mercury’s magnetic field analysis. The mathematical foundations and the practical application of the Capon method are discussed in a rigorous fashion by extending its linear algebraic derivation in view of planetary magnetic field studies. Furthermore, the optimization of Capon’s method by making use of diagonal loading is considered.

How to cite: Töpfer, S., Narita, Y., Heyner, D., Kolhey, P., and Motschmann, U.: Capon’s method for planetary magnetic field analysis, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8163, https://doi.org/10.5194/egusphere-egu21-8163, 2021.