European Exploration of Mars: from Mars Express to ExoMars and beyond
Martian research in Europe has grown exceptionally over the past decades, first thanks to the longstanding achievements of the Mars Express community and more recently thanks to the great contributions of the ExoMars 2016 Trace Gas Orbiter mission, leading Europe to a prime role within the international martian community. This valuable experience has paved the way for the new exciting discoveries expected in the next years from the ExoMars Rover and Surface Platform and in the future by the Mars Sample Return programme.
The aim of this session is to recognize the experience gained with European Mars missions and promote new synergies to enhance the collaboration within the European science community, in close coordination with other international agencies (NASA, Roscomos, JAXA, CSA, etc.)
This session welcomes contributions from any field of Martian scientific research, including also operational, technical and interdisciplinary aspects involving the different Mars missions, especially those covering multi-mission and international collaborations over a wide range of topics: Mars subsurface, surface geology and mineralogy, atmosphere, magnetosphere, martian moons and any potential exo-biological implication in the context of the new exploration missions.
Session summary is now available online with the showcase presentation given by the Project Scientists of all ESA's Mars missions. This includes the latest science highlights from Mars Express and Trace Gas Orbiter, the status of the ExoMars 2022 Rover and Surface Platform and the preparations for the Mars Sample Return programme. Please visit the presentations and do not hesitate to comment and discuss with all authors, especially Early Career Researchers.
Dmitrij Titov, Jean-Pierre Bibring, Alejandro Cardesin, Tom Duxbury, Francois Forget, Marco Giuranna, Francisco González-Galindo, Mats Holmström, Ralf Jaumann, Anni Määttänen, Patrick Martin, Franck Montmessin, Roberto Orosei, Martin Pätzold, and Jeffrey Plaut and the Mex Sgs Team
After 16 years in orbit Mars Express remains one of ESA’s most scientifically productive Solar System missions which publication record now approaches 1300 papers. Characterization of the geological processes on a local-to-regional scale by HRSC, OMEGA and partner experiments on NASA spacecraft has allowed constraining land-forming processes in space and time. Recent studies suggest geological evidence of a planet-wide groundwater system on Mars and surface clay formation during short-term warmer and wetter conditions on a largely cold ancient Mars. HRSC team released the Digital Elevation Model (DEM) of the MC-11 quadrangle and the Southern polar cap at 50 m/px resolution. Mars Express provided essential contribution to the selection of the Mars-2020 landing sites and supporting characterization of potential landing sites for Chinese Tianwen-1 mission.
One-and-one-half decade of monitoring of atmospheric parameters such as temperature, dust loading, water vapor and ozone abundance, water ice and CO2 clouds distribution, collected by SPICAM, PFS, OMEGA, HRSC and VMC together with subsequent modeling have provided key contributions to our understanding of the Martian climate. In 2019 PFS confirmed observations of a methane abundance “spike” in the Gale crater observed in situ by the Curiosity Rover. Recent similar quasi-simultaneous observations were in disagreement, thus indicating that the methane “enigma” continues. This poses a significant challenge to both observers and modelers. The radio-science experiment MaRS revealed fine structure of the boundary layer which depth varies from 2 km in topographic lows to ~10 km over highlands.
Observations of the ion escape during a complete solar cycle revealed that ion escape can be responsible for removal of about 10 mbar of the atmosphere over Mars’ history. This implies existence of other, more effective, escape channels. The structure of the ionosphere derived from MARSIS and MaRS sounding was found to be significantly affected by the solar activity, dust loading in the lower atmosphere, and crustal magnetic field. The observations suggest that the sunlit ionosphere over the regions with strong crustal fields is denser and extends to higher altitudes as compared to the regions with no crustal anomalies. Ionospheric models aim at creating user-friendly data base of plasma parameters that would be of great service to the planetary community. Focused exploration of the Martian moons continues.
The mission is notionally extended till the end of 2022. A science case for the mission extension till the end of 2025 has been submitted. The talk will give the Mars Express status, review the recent science highlights, and outline future plans including synergistic science with TGO.
How to cite:
Titov, D., Bibring, J.-P., Cardesin, A., Duxbury, T., Forget, F., Giuranna, M., González-Galindo, F., Holmström, M., Jaumann, R., Määttänen, A., Martin, P., Montmessin, F., Orosei, R., Pätzold, M., and Plaut, J. and the Mex Sgs Team: Mars Express science highlights and future plans, Europlanet Science Congress 2020, online, 21 Sep–9 Oct 2020, EPSC2020-720, https://doi.org/10.5194/epsc2020-720, 2020.
Julia Marín-Yaseli de la Parra, Alejandro Cardesín-Moinelo, Donald Merritt, Michel Breitfellner, Manuel Castillo Fraile, Emmanuel Grotheer, Marc Costa í Sitjà, Carlos Muñiz Solaz, Eleni Ravanis, Patrick Martin, and Dimitri Titov
MEX remains one of ESA’s most scientifically productive missions and has fully accomplished its initial mission objectives. It was the first European mission to Mars and the first ESA mission to orbit another planet. Its global surveys of the surface, the atmosphere and the plasma environment of the Red Planet were possible to achieve thanks to the elliptical orbit of MEX. The mission provides a unique platform for Mars climate evolution research to help understand the complex atmospheric processes present on Mars. This scenario is ideal for fulfilling diverse science goals from the instruments on board with new scientific and operational challenges in the coming years.
NEW CHALLENGES FOR MISSION EXTENSIONS 2021-2022 and 2023-2025
In addition to the regular global surface, climate and plasma monitoring, the future mission extensions will have various new challenging science campaigns. The scientific goals for the extensions 2021-2022 and 2023-2025 are described in detail by (Titov et al EPSC2020).
Figure 1. Main scientific and operational seasons for Mars Express between 2021 and 2025
These are some of the new challenging objectives that are planned for the mission extensions :
Hi-resolution observations of atmosphere & ionosphere
First active plasma sounding at another planet (MARSIS/ASPERA)
MEX/TGO inter-spacecraft occultation radio science
Ionosphere and plasma at Solar Maximum
Global topography (completion of colour & stereo imagery)
Active & transient surface effects
Phobos observatios with full instrument suite
Joint observations with TGO and Rosalind Franklin (RSP)
With the successive confirmations of the Mars Express (MEX) mission extension, doors are opened to gather new science. New technological challenges appear in the Science Ground Segment (SGS) of the European Space Agency, which is characterized by its variability, flexibility and diversity.
IMPLEMENTATION OF NEW SCIENCE OBSERVATIONS
In this manuscript we present here various new observation campaigns that are defined to fulfil the scientific objectives of the new mission extensions and summarize the inventive modifications our team has made in order to continue with the flexibility in terms of planning the mission extensions.
Mars Express has a highly elliptical polar orbit that crosses the equatorial orbit of Phobos every 5~7 months (Figure 2 and Witasse et al.2014). During these seasons, several flyby campaigns are organized and all instruments are pointed to the moon with different observation requirements (illumination, distance, rotation rates, etc).
Figure 2. Illustration of Mars Express crossing Phobos orbit. Image taken by HRSC in November
2019, orbit 20076, at a distance of ~2400 km (ESA/DLR/FU Berlin).
A good example of new science campaigns are the new Local Time Scans, where the spacecraft is rotated (Figure 3) to cover a wide range of local times and longitudes in the same latitude region.
Figure 3. Mars Express Local Time Scans. Left: spacecraft is rotated along the scan direction,
perpendicular to the satellite motion. Right: three local time scans over Hellas planitia; red circles
show PFS field of view; colours represent illumination angle (cyan is dark around local morning,
yellow is brighter close to local noon). (Credit ESA/DLR/FU Berlin/MAPPS/J.Marín-Yaseli)
This Local Time Scanning campaign was created in 2019 based on a new request by the Planetary Fourier Spectrometer (PFS) to increase the local time coverage of the measurements to improve the climatic record, which was limited by the spacecraft trajectory. Based on this requirement, a new pointing type was defined to improve the local time coverage over certain regions of the planet. This new observation type is now used by all spectrometers (PFS, SPICAM, OMEGA) allowing for the identification of inter-diurnal variations in certain regions of interest, as shown for Hellas Planitia above.
New tests will be executed throughout summer 2020 to assess the performance of radio measurements at the exit of the earth occultations (Figure4). Although the operational concepts of ingress+egress occultations were formulated at the beginning of the mission, it was not until mid-2020 that the first campaigns were revised for execution. The egress occultations will bring the opportunity to observe wider latitude/longitude areas still uncovered by previous campaigns.
Figure 4. Radio Science ingress+egress occultations as seen from the Earth (left) and plotted against
latitude and true anomaly (right).
The first tests to carry out radio science communications between the two spacecraft are expected to start by the end of 2020 (Figure 5 and Cardesín-Moinelo, et al. Icarus 2020). The technical and scientific requirements for these new observations impose new challenges in the operations of the two missions. In particular, the preparation of the observations requires a long-term geometrical analysis of the pointing requirements and visibility opportunities between the two spacecraft, as well as detailed coordination between the scientific and technical teams for the configuration and execution of the measurements to ensure the correct data interpretation.
Figure 5. Illustrations of radio occultation between Mars Express and Trace Gas Orbiter. Bottom-right
shows the good latitude/longitude coverage for the occultations. (ESA/SPICE/Cosmographia)
Planning the science operations for MEX continues to be a challenge. Coordination and fast changes among the different teams at ESA enables Mars Express to continue doing science for many more years. It requires a qualified science operations team with both engineering and scientific experience to achieve the goals of the mission. It is vital to take advantage of long term missions such as MEX in order to transfer the planning knowledge and experience to complex planetary missions of the future.
How to cite:
Marín-Yaseli de la Parra, J., Cardesín-Moinelo, A., Merritt, D., Breitfellner, M., Castillo Fraile, M., Grotheer, E., Costa í Sitjà, M., Muñiz Solaz, C., Ravanis, E., Martin, P., and Titov, D.: Challenges for the New Science Campaigns in Mars Express future Mission Extensions, Europlanet Science Congress 2020, online, 21 Sep–9 Oct 2020, EPSC2020-632, https://doi.org/10.5194/epsc2020-632, 2020.
Sebastian H.G. Walter, Greg G. Michael, Klaus Gwinner, and Ralf Jaumann
Introduction: Current efforts for image mosaics from the High Resolution Stereo Camera (HRSC, Jaumann, 2007) on board Mars Express are ongoing (Michael et al. 2016, Michael et al., 2019). Usually, illumination effects between adjacent single images related to the planetary curvature are reduced by using a Lambert correction and subsequent normalization to a common brightness reference. Here we present an extended correction of topography-induced shading effects by using the illumination angles with reference to the local topography represented by the digital terrain model (DTM) associated to every single HRSC scene, resulting in top-of-the-atmosphere albedo images of the surface.
Scattering models: When used for illumination corrections taking the local topography into account, the Lambertian model and its associated cosine correction tends to over-correct on large incidence angles (under-illuminated pixels), as observed on crater slopes at low Sun angles. Therefore we do not consider it for our work but use it as a reference for comparison reasons (see Fig. 1 top -- the saturation level of one is reached at around 70° effective incidence angle).
The one-parameter model by Minnaert (Minnaert, 1941) is known for its good reproduction of the Martian surface. Depending on its power-law parameter k, the saturation effect of the correction appears at very high incidence angles only and is therefore better suited for topographic corrections. Still, in the case of HRSC, the Sun incidence angle on the ellipsoid is often higher than 60° and adding the slope angles results in incidence angles higher than 80°. This leads to very bright over-corrected pixels in highly inclined areas facing away from the Sun (see Fig. 1 middle -- depending on the k parameter, the saturation level is reached at around 80° incidence).
The correction used by Teillet et al. (1982) is well suited for topographic corrections due to its minimal amount of overcorrection (cf. Fig. 1 bottom for plots of varying parameter settings and Fig. 2 for the result). The single parameter is derived by a relation of the incidence on the ellipsoid to the mean incidince with regards to the topography.