Research Institute in Astrophysics and Planetology
Recent publications
The “Mars Microphone” is one of the five measurement techniques of SuperCam, an improved version of the ChemCam instrument that has been functioning aboard the Curiosity rover for several years. SuperCam is located on the rover’s Mast Unit, to take advantage of the unique pointing capabilities of the rover’s head. In addition to being the first instrument to record sounds on Mars, the SuperCam Microphone can address several original scientific objectives: the study of sound associated with laser impacts on Martian rocks to better understand their mechanical properties, the improvement of our knowledge of atmospheric phenomena at the surface of Mars such as atmospheric turbulence, convective vortices, dust lifting processes and wind interactions with the rover itself. The microphone also helps our understanding of the sound signature of the different movements of the rover: operations of the robotic arm and the mast, driving on the rough surface of Mars, monitoring of the pumps, etc. The SuperCam Microphone was delivered to the SuperCam team in early 2019 and integrated at the Jet Propulsion Laboratory (JPL), Pasadena, CA with the complete SuperCam instrument. The Mars 2020 Mission launched in July 2020 and landed on Mars on February 18, 2021. The mission operations are expected to last until at least August 2023. The microphone is operating perfectly.
Plain Language Summary Earthquakes, avalanches, icequakes and landslides originate from a common process: rupture at a material interface. During a rupture, for example, when a landslide slips, a characteristic pattern of seismic waves is created. This pattern differs at the earth's surface and the rupture interface, which is the source of the seismic waves inside the earth. Usually scientists only measure the waves arriving at the surface and need to deduce the wave pattern inside the earth from the surface measurement. We build a laboratory experiment which enables us to film wave propagation around the rupture surface, as if we had a camera inside the material. We film waves emitted during and prior to a rupture. For a soft material on a hard surface, such as encountered in icequakes or landslides, a single force model better explains the observed wave pattern than the commonly used model of four distributed forces. The rupture moves faster than shear waves propagate which results in a supershear cone, the elastic equivalent to the acoustic Mach cone created by supersonic aircrafts. For two materials of similar hardness, such as encountered in earthquakes, the classic model of four forces better explains the ruptures, which travel at sub‐shear speed.
Mismanaged plastic waste interacts with secondary environmental pollutants, potentially aggravating their impact on ecosystems and human health. Here we characterized the natural and artificial radionuclides in polyethylene terephthalate bottles collected from the industrial littoral discharge of a phosphate fertilizer plant. The activity concentrations in littered bottles ranged from 0.47 (208Tl) to 12.70 Bq·kg-1 (226Ra), with a mean value of 5.30 Bq·kg-1. All the human health risk assessment indices (annual intake, annual effective dose, and excess lifetime cancer risk) estimated for radionuclides associated with ingestion and inhalation of microplastics were below international safety limits. Our results demonstrated that PET can be loaded with natural and artificial radionuclides, and potentially act as a carrier to transfer radionuclides to humans, posing a new potential health risk. Increased use, mismanagement and fragmentation of plastic waste, and continued interaction of plastic waste with radioelements may lead to enhanced radiation exposure in the future.
Flying space missions to the different destinations of the Solar System, and maximizing their science return, relies on the availability for generic technical infrastructures and services to provide support to groups of missions rather than specialized support systems tailored to individual missions. In this chapter, we present an overview of the different types of infrastructures and services that will be needed to support the group of representative missions identified in Chapter 4 (Pillar 2 report). We first review infrastructures and services that support robotic, sample return, and human exploration missions: launch, telecommunication and navigation services, space stations and Moon outposts, and sample curation facilities. All these missions also require the support of Solar-System-scale space weather services. Complementary to space missions, Earth-based telescopes, ground-based simulation facilities, and laboratory experiments provide key scientific information to provide an in-depth understanding of our planetary system and its constituent objects. Finally, advanced data systems evolving toward a global Solar System Virtual Observatory (VO) will provide an integrated service to all scientific users, enabling access diverse data sources with the aim of producing new scientific knowledge. Virtual navigation in this VO will also offer a unique way for teachers, students, and the public to develop their own experience of exploring the Solar System. Most importantly, the VO will contribute to the inspiration and training of the new generations of space scientists, engineers, and managers who will turn the Horizon 2061 perspective presented in this book into reality.
With the discovery of thousands of extrasolar planetary systems it becomes more and more evident that a large variety of planetary system architectures, including very different types of planets, have been realized in nature. Our solar system is just one among many. We do not know yet whether the evolution of the planets and moons in the solar system is typical for such objects in similar environments, or not. This includes in particular the capability to develop habitable surface conditions, or even life. Planets orbiting host stars different to our Sun can experience very different environmental conditions such as stellar spectral energy distributions and harsh cosmic rays impacting the orbiting planets. The dynamical evolution of planetary systems depends on the formation processes and interactions with the protoplanetary disk as well as migration processes. Looking at extrasolar planets in the sky today, we see systems in different astrophysical environments, at different ages and with different evolutionary histories. As outlined above, the number of processes shaping the characteristics of planets is large. Yet, for extrasolar planets the number of observables is small. Observational constraints are usually limited to orbital parameters, planetary masses, radii, and some of the atmospheric constituents. In fortunate cases additional constraints like magnetic fields and Love numbers will become accessible in the future. Additional constraints are given by the host star characteristics (metallicity, composition, age, temperature, etc.), but the link between stellar properties and planetary characteristics is complex and not fully understood yet. In view of this limited achievable data set, it becomes vital to better understand how we can learn from our detailed knowledge of the bodies in the solar system to better understand the planets and moons in extrasolar systems. Vice versa, extrasolar systems show us the possible variety of planetary systems, which helps us in particular to better understand planet formation processes. Furthermore, with the increasing number of terrestrial planets found orbiting in the habitable zone of their hosts, the number of potential targets to search for life significantly increases. Finding clear evidence for life will, however, require a very good understanding of the biogenic processes on planets, their interaction with the atmosphere, and a careful study of nonbiogenetic processes to avoid false alarms. So far, we know life only in our solar system, on Earth. It is therefore crucial to bring together the knowledge we have from both the detailed solar system view and the statistical view of a large number of extrasolar planets. After a brief review of the missions planned to study solar system and extrasolar planets in the future, our knowledge of planets and planetary systems is reviewed and prospects for synergies of solar system and exoplanet research discussed. The discussion includes planet formation processes as well as the geophysical evolution of planets and moons. Particular emphasis is given to the understanding of habitats and search for biosignatures in extrasolar planets and lessons learned from the Earth. Future large telescope facilities will allow us to search for biosignatures outside the solar system, enhancing the prospects to answer the long-standing question whether life has developed elsewhere in our galaxy, at least within our neighborhood. The contents presented in this chapter draw heavily on the presentations, discussions, and final report of the forum “Solar System/Exoplanet Science Synergies in a multi-decadal Perspective” jointly organized by the Europlanet Research Infrastructure and the International Space Science Institute in Bern, Switzerland, on February 19 and 20, 2019.
The primary objective of this chapter is to present an overview of the different key technologies that will be needed in order to fly the technically most challenging of the representative missions identified in Chapter 4 (the Pillar 2 Horizon 2061 report, Lasue et al., 2021). It starts with a description of the future scientific instruments which will address the key questions of Horizon 2061 described in Chapter 3 (the Pillar 1 Horizon 2061 report, Dehant et al., 2021) and the new technologies that the next generations of space instruments will require (Section 2). From there, the chapter follows the line of logical development and implementation of a planetary mission: Section 3 describes some of the novel mission architectures that will be needed and how they will articulate interplanetary spacecraft and science platforms; Section 4 summarizes the system-level technologies needed: power, propulsion, navigation, communication, advanced autonomy on-board planetary spacecraft; Section 5 describes the diversity of specialized science platforms that will be needed to survive, operate, and return scientific data from the extreme environments that future missions will target; Section 6 describes the new technology developments that will be needed for long-duration missions and semipermanent settlements; finally, Section 7 attempts to anticipate some of the disruptive technologies that should emerge and progressively prevail in the decades to come to meet the long-term needs of future planetary missions.
After a brief introductory historical perspective, this chapter reviews the role played by international collaboration in the implementation of the four pillars. It addresses the particularly important perspective of enabling the ambitious set of representative missions identified in Pillar 2, many of which are out of reach by a single space agency or accessible to only a small subgroup of them: international cooperation appears as one of the most promising avenues to accomplish these missions and to provide a valuable role to each space-faring nation in planetary exploration. It then reviews some of the mechanisms for international collaboration and describes some of the most successful ones. Finally, it describes the roles that international cooperation and public–private collaborations are expected to play at the 2061 horizon.
This chapter reviews for each province and destination of the Solar System the representative space missions that will have to be designed and implemented by 2061 to address the six key science questions about the diversity, origins, workings, and habitability of planetary systems (described in Chapter 1) and to perform the critical observations that have been described in Chapter 3 and partly Chapter 2. It derives from this set of future representative missions, some of which will have to be flown during the 2041–61 period, the critical technologies and supporting infrastructures that will be needed to fly these challenging missions, thus laying the foundation for the description of technologies and infrastructures for the future of planetary exploration that is given in Chapters 5 and 6Chapter 5Chapter 6, respectively.
This introductory chapter describes the science base, objectives, and methods of the “Planetary Exploration, Horizon 2061” foresight exercise. It first describes the class of astrophysical objects whose future investigation and improved understanding are the objective of the Horizon 2061 foresight: planetary systems. It then introduces the four “pillars” of science-driven planetary exploration: (1) the science of planetary systems—six key science questions about planetary systems, their origins, evolution, workings, and habitability, which can be addressed via in situ exploration only in the solar system; (2) the space missions needed to perform the observations that can inform these questions; (3) the technologies needed to fly these challenging space missions; (4) the space-based and ground-based infrastructures and services needed to support these missions to all destinations in the Solar System. It then describes the method followed by the “Horizon 2061” exercise to successively build these four “pillars,” and how this method and work flow are reflected in the structure of the book and translated into each of its seven chapters.
This chapter reviews the way the six key questions about planetary systems, from their origins to the way they work and their habitability, identified in Chapter 1 (Blanc et al., 2021), can be addressed by means of solar system exploration, and how one can find partial answers to these six questions by flying to the different provinces to the solar system: terrestrial planets, giant planets, small bodies, and up to its interface with the local interstellar medium. It derives from this analysis a synthetic description of the most important space observations to be performed at the different solar system objects by future planetary exploration missions. These “observation requirements” illustrate the diversity of measurement techniques to be used as well as the diversity of destinations where these observations must be made. They constitute the base for the identification of the future planetary missions we need to fly by 2061, which are described in Chapter 4.
Glen Torridon is a topographic trough located on the slope of Aeolis Mons, Gale crater, Mars. It corresponds to what was previously referred to as the “clay‐bearing unit,” due to the relatively strong spectral signatures of clay minerals (mainly ferric smectites) detected from orbit. Starting in January 2019, the Curiosity rover explored Glen Torridon for more than 700 sols (Martian days). The objectives of this campaign included acquiring a detailed understanding of the geologic context in which the clay minerals were formed, and determining the intensity of aqueous alteration experienced by the sediments. Here, we present the major‐element geochemistry of the bedrock as analyzed by the ChemCam instrument. Our results reveal that the two main types of bedrock exposures identified in the lower part of Glen Torridon are associated with distinct chemical compositions (K‐rich and Mg‐rich), for which we are able to propose mineralogical interpretations. Moreover, the topmost stratigraphic member exposed in the region displays a stronger diagenetic overprint, especially at two locations close to the unconformable contact with the overlying Stimson formation, where the bedrock composition significantly deviates from the rest of Glen Torridon. Overall, the values of the Chemical Index of Alteration determined with ChemCam are elevated by Martian standards, suggesting the formation of clay minerals through open‐system weathering. However, there is no indication that the alteration was stronger than in some terrains previously visited by Curiosity, which in turn implies that the enhanced orbital signatures are mostly controlled by non‐compositional factors.
Magnetic field draping occurs when the magnetic field lines frozen in a plasma flow wrap around a body or plasma environment. The draping of the interplanetary magnetic field (IMF) around the Earth’s magnetosphere has been confirmed in the early days of space exploration. However, its global and three‐dimensional structure is known from modeling only, mostly numerical. Here, this structure in the dayside of the Earth’s magnetosheath is determined as a function of the upstream IMF orientation purely from in‐situ spacecraft observations. We show the draping structure can be organized in three regimes depending on how radial the upstream IMF is. Quantitative analysis demonstrates how the draping pattern results from the magnetic field being frozen in the magnetosheath flow, deflected around the magnetopause. The role of the flow is emphasized by a comparison of the draping structure to that predicted to a magnetostatic draping.
Plain Language Summary On 7 June 2021 the Juno mission came as close as 1,046 km from the surface of Ganymede, the largest moon in the solar system. Similar close encounters were previously made by the Galileo mission, from which we learned much of the interaction of the moon, with its own intrinsic magnetic field, and Jupiter's magnetosphere. In this paper, we present an overview of the plasma observations, that is, ions and electrons in the lower part of the energy spectrum, made by the Jovian Auroral Distributions Experiment. We find that the ion composition near Ganymede is very different than that from Jupiter's magnetosphere. Near Ganymede, the plasma composition is dominated by molecules and ions that originate from water in the atmosphere or the surface. One surprising observation is the presence of the molecular ion H3⁺ inside Ganymede's magnetosphere and in a region just outside and downstream, that we call the wake. H3⁺ was not included in various models of Ganymede's atmosphere.
During the first 2934 sols of the Curiosity rover’s mission 33,468 passive visible/near-infrared reflectance spectra were taken of the surface by the mast-mounted ChemCam instrument on a range of target types. ChemCam spectra of bedrock targets from the Murray and Carolyn Shoemaker formations on Mt. Sharp were investigated using principal component analysis (PCA) and various spectral parameters including the band depth at 535 nm and the slope between 840 nm and 750 nm. Four endmember spectra were identified. Passive spectra were compared to Laser Induced Breakdown Spectroscopy (LIBS) data to search for correlations between spectral properties and elemental abundances. The correlation coefficient between FeOT reported by LIBS and BD535 from passive spectra was used to search for regions where iron may have been added to the bedrock through oxidation of ferrous-bearing fluids, but no correlations were found. Rocks in the Blunts Point-Sutton Island transition that have unique spectral properties compared to surrounding rocks, that is flat near-infrared (NIR) slopes and weak 535 nm absorptions, are associated with higher Mn and Mg in the LIBS spectra of bedrock. Additionally, calcium-sulfate cements, previously identified by Ca and S enrichments in the LIBS spectra of bedrock, were also shown to be associated with spectral trends seen in Blunts Point. A shift towards steeper near-infrared slope is seen in the Hutton interval, indicative of changing depositional conditions or increased diagenesis.
The Mastcam‐Z radiometric calibration targets mounted on the NASA's Perseverance rover proved to be effective in the calibration of Mastcam‐Z images to reflectance (I/F) over the first 350 sols on Mars. Mastcam‐Z imaged the calibration targets regularly to perform reflectance calibration on multispectral image sets of targets on the Martian surface. For each calibration target image, mean radiance values were extracted for 41 distinct regions of the targets, including patches of color and grayscale materials. Eight strong permanent magnets, placed under the primary target, attracted magnetic dust and repelled it from central surfaces, allowing the extraction of radiance values from eight regions relatively clean from dust. These radiances were combined with reflectances obtained from laboratory measurements, a one‐term linear fit model was applied, and the slopes of the fits were retrieved as estimates of the solar irradiance and used to convert Mastcam‐Z images from radiance to reflectance. Derived irradiance time series are smoothly varying in line with expectations based on the changing Mars‐Sun distance, being only perturbed by a few significant dust events. The deposition of dust on the calibration targets was largely concentrated on the magnets, ensuring a minimal influence of dust on the calibration process. The fraction of sunlight directly hitting the calibration targets was negatively correlated with the atmospheric optical depth, as expected. Further investigation will aim at explaining the origin of a small offset observed in the fit model employed for calibration, and the causes of a yellowing effect affecting one of the calibration targets materials.
Plain Language Summary The surface a solar system body that does not have an atmosphere can be directly bombarded and processed by the small positively charged particles ejected by the Sun, known as solar wind ions. At the Earth Moon, previous work discovered that 0.1%–1% of the solar wind protons hitting the lunar surface are backscattered in space as charged particles instead of traveling through the planetary surface. The only other place where this fundamental process may have been detected so far is Phobos, a small rocky moon that orbits the red planet Mars. Indeed, ESA's satellite Mars Express (MEX) may have previously observed such protons at Phobos, but these detections remain uncertain. To advance on the question of solar wind proton backscattering at Phobos, we analyze in this article the proton measurements gathered by NASA's Mars Atmosphere and Volatile EvolutioN mission (MAVEN) mission close to Phobos. Models are employed to identify the origin of the protons observed by MAVEN and we find no evidence of protons backscattered by the Martian moon. This result puts into new context the past MEX detections and the future observation attempts of the upcoming JAXA Martian Moons Exploration mission.
Askival is a light‐toned, coarsely crystalline float rock, which was identified near the base of Vera Rubin Ridge in Gale crater. We have studied Askival, principally with the ChemCam instrument but also using APXS compositional data and MAHLI images. Askival and an earlier identified sample, Bindi, represent two rare examples of feldspathic cumulate float rocks in Gale crater with >65% relict plagioclase. Bindi appears unaltered whereas Askival shows textural and compositional signatures of silicification, along with alkali remobilization and hydration. Askival likely experienced multiple stages of alteration, occurring first through acidic hydrolysis of metal cations, followed by deposition of silica and possible phyllosilicates at low T and neutral‐alkaline pH. Through laser‐induced breakdown spectroscopy compositional analyses and normative calculations, we suggest that an assemblage of Fe‐Mg silicates including amphibole and pyroxene, Fe phases, and possibly Mg‐rich phyllosilicate are present. Thermodynamic modeling of the more pristine Bindi composition predicts that amphibole and feldspar are stable within an upper crustal setting. This is consistent with the presence of amphibole in the parent igneous rocks of Askival and suggests that the paucity of amphiboles in other known Martian samples reflects the lack of representative samples of the Martian crust rather than their absence on Mars.
In this study we present the observation of Mercury’s inner southern magnetosphere and surrounding regions, never previously explored, as detected by the two ion sensors of the instrument package: ‘Search for Exospheric Refilling and Emitted Natural Abundances’ (SERENA), named ‘Planetary Ion CAMera’ (PICAM) and ‘Miniaturized Ion Precipitation Analyzer’ (MIPA), on board BepiColombo mission during the first Mercury flyby, on 1st October 2021. Here we show the analysis of the data acquired during this flyby, a glimpse of what we will get from the nominal mission: in particular we observe and describe specific ion features nearby and inside the Hermean environment, like: intermittent high energy signal due to an interplanetary magnetic flux rope; magnetospheric ions with different energy drifting at low altitudes above the planet and determining specific plasma regimes; ion signals detected outside the magnetosphere at low energy.
In face of global warming, academics have begun to consider and analyze the environmental and carbon footprints associated with their professional activity. Among the several sources of greenhouse gas (GHG) emissions from research activities, air travel - one of the most visible and unequally distributed fraction of this footprint - has received much attention. Of particular interest is the question of how air travel may be related to scientific success or visibility as defined by current academic evaluation norms, notably bibliometric indicators. Existing studies, conducted over a small sample of individuals or within specific disciplines, have failed to demonstrate the existence of an association between bibliometric indicators and the frequency of air travel. Here, using a comprehensive dataset aggregating the answers from over 6000 respondents to a survey sent to randomly selected scientists and staff across all research disciplines in France, we show that a strong publication rate and h}-index are significantly associated with higher individual air travel GHG emissions. This relationship is robust to the inclusion of the effects of gender, career stage and disciplines. Our results indicate that evaluation through bibliometric indicators favors individuals who adopt practices that are less sustainable.
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Sebastien Deheuvels
  • Physics of the Sun, Stars and Exoplanets
Toulouse, France