Jeremy Brossier

National Institute of Astrophysics | INAF · Institute for Space Astrophysics and Planetology IAPS

An essential part of the Exomars 2022 payload is the Mars Multispectral Imager for Subsurface Studies (Ma_MISS) experiment hosted by the drill system. Ma_MISS is a visible and near-infrared (0.4–2.3 μ m) miniaturized spectrometer with an optical head inside the drill tip capable of observing the drill borehole with a spatial resolution of 120 μ m....

Oxia Planum (335.5°E, 18.2°N) is selected as the landing site for ExoMars rover mission (ESA/Roscosmos), where the “Rosalind Franklin” rover is scheduled to land in the decade. The region reveals several extensive clay-bearing outcrops recently exhumed, where biosignatures are possibly preserved. The objectives of the mission are to search for orga...

Exploration of Venus in the 1970–1990s revealed that the geology of Venus, the most Earth-like of the terrestrial planets, was decidedly un-Earth-like, with no plate tectonics, and no record of the first 80% of its history. A major outstanding question is whether Venus is still volcanically active today. We find that regions of Ganis Chasma have lo...

The dominant source of sediment on Venus is thought to be impact cratering, wherein crater ejecta is redistributed across the planet by winds. Here we provide a refined global sediment budget for Venus by mapping and quantifying the volume of sediment from impact craters observable in Magellan data using updated methodology. We improve on previous...

Clay minerals detected on Mars are valuable targets to seek traces of life on the planet, where biosignatures might be preserved. Here, we report an in-depth spectral analysis of clay-rich outcrops identified in northern Xanthe Terra (300°-320°E, 10°-20°N). We focused particularly on the absorptions centered in the 1.0-2.6 μm spectral range to (1)...

Several regions located along circum-Chryse Planitia may indicate a long-lived aqueous history, where infrared data reveal extensive outcrops of recently exhumed clay-rich rocks. These outcrops are appealing “windows” to seek signs of past or pre-sent life on Mars, as biosignatures might be preserved therein. Here, we focus on clay-bearing outcrops...

ExoMars rover mission is expected to deliver the “Rosalind Franklin” rover to explore Oxia Planum, a region straddling between Arabia Terra and Chryse Planitia (335.5E, 18.2N). Oxia Planum shows evidences of a long-lasting aqueous activity, where near-infrared data reveal widespread outcrops of recently exhumed clay-rich deposits. ExoMars rover wil...

ExoMars rover mission is expected to deliver the “Rosalind Franklin” rover to explore Oxia Planum, a region straddling between Arabia Terra and Chryse Planitia (335.5E, 18.2N). Oxia Planum shows evidences of a long-lived aqueous activity, where near-infrared data reveal widespread outcrops of recently exhumed clay-rich deposits. ExoMars rover will...

Mars is a primary destination to search for signs of life and probing the subsurface is a key element in this search. Access to the Martian subsurface, under most altered layers, is needed to understand the nature, timing and duration of alteration and sedimentation processes on Mars, as well as habitability conditions. For such a reason, ExoMars r...

The ExoMars rover mission will be looking for biosignatures (i.e. signs of past and present life) in Oxia Planum, Mars. The landing site is located between 16°and 19°N and 334°to 337°E where the ancient cratered terrains transition into the low-lying plains of Chryse Planitia. The area of interest is situated between Ares Vallis and Mawrth Vallis i...

Clay minerals are widespread on Mars and are suitable targets to seek traces of life on the planet. Here, we propose an in-depth spectral analysis of clay-rich outcrops identified in northern Xanthe Terra (300–320°E, 10–20°N). We focus particularly on the absorptions centered in the 1.0–2.6 µm spectral range, aiming to (1) better constrain the natu...

Exploration of Venus in the 1970–1990’s revealed that the geology of Venus, the most Earth-like of the terrestrial planets, was decidedly un-Earth-like, with no plate tectonics, and no record of the first 80% of its history. A major outstanding question is whether Venus is still volcanically active today. We find that regions of Ganis Chasma have l...

ExoMars program is expected to deliver the Rosalind Franklin rover to explore Oxia Planum (335.6°E, 18.2°N), a region where biosignatures might be preserved. Oxia Planum bears several morphological and mineralogical evidences of a long-lasting aqueous (fluvial, lacustrine and deltaic) activity. Orbital data show extensive outcrops of ancient clay-r...

ExoMars 2022 mission is scheduled to launch in 2022 and land on Mars roughly nine months later. It will deliver the Rosalind Franklin rover to explore Oxia Planum (18.2°N, 335.5°E), a region where biosignatures might be preserved. Oxia Planum bears several morphological and mineralogical evidences of a long-lived aqueous (fluvial, lacustrine and de...

Tesserae are some of the oldest terrains on Venus and may have formed during a period with substantially different climactic conditions than today, preserving a record of this more temperate climate. A landed mission to tesserae could address major science questions, constraining internal and surface conditions earlier in the planet’s history.

Yardangs are streamlined ridges that form from erosion of friable substrate. These wind-abraded features occur in a variety of arid settings on Earth, as well as on Mars, most famously in the Medusae Fossae Formation (Ward and Greeley, 1984; Mandt et al., 2008; Ding et al., 2020). On Venus, a possible yardang field has been identified near the 280...

Ganis Chasma (192°E, 18°N) is a region in Atla Regio where recent rift-associated volcanic activity has been reported (Shalygin et al., 2015). This interpretation is primarily based on the Venus Monitoring Camera (VMC) data from Venus Express and the detection of transient bright spots. These bright spots would be consistent with the extrusion of l...

The high temperature of the Venus surface prohibits fluvial processes in the current era. The generation of sediment today therefore is limited to weathering via chemical reactions, mass wasting, volcanic output, deflation and physical communition via impact (Kreslavsky and Bondarenko, 2017). Of these, impact-derived sediment is predicted to be dom...

NASA's Magellan mission revealed that many Venus highlands exhibit low radar emissivity values at higher altitudes. This phenomenon is ascribed to the presence of minerals having high dielectric constants, produced or stabilized by temperature-dependent chemical weathering between the rocks and the atmosphere. Some large volcanoes on Venus have mul...

Recent mineralogical studies suggest past aqueous activities in the 150-km-wide Robert Sharp impact crater, the western neighbor of Gale crater on Mars. Despite their mineralogical similarities, Robert Sharp and Gale craters display very different morphologies. Using high-resolution orbital images, we made morphological and stratigraphical analyses...

The high temperatures (740K) of the Venus surface prohibit fluvial processes. Therefore the sediment on Venus’ surface is the product of impact cratering. This sediment is deposited in parabola-shaped ejecta blankets carried westward by high altitude winds. The thickest and assumed newest deposits for 49 of the ~900 Venus craters are visible in Mag...

Recent mineralogical studies suggest past aqueous activities in the 150-km-wide Robert Sharp impact crater, the western neighbor of Gale crater on Mars. Despite their mineralogical similarities, Robert Sharp and Gale craters display very different morphologies. Using high-resolution orbital images, we made morphological and stratigraphical analyses...

A decline in radar emissivity at many Venus mountaintops [1,2] is thought to be the result of atmosphere-surface interactions in the highlands, where temperatures are lower [3–5]. These reactions are a function of rock composition, atmospheric composition, and degree of weathering. Recent analysis of NASA’s Magellan radar data [6,7] reveal that som...

Numerous studies show that major Venus highlands display anomalously high radar reflectivity and low radar emissivity relative to the planetary average. This is thought to be the result of the formation of minerals having high dielectric constants via weathering reactions occurring between the surface and the deep atmosphere in these elevated terra...

Tesserae are heavily deformed terrains that cover about 8% of Venus’ surface (Ivanov and Head, 1996) and consistently appear as the stratigraphically oldest mate-rial on a planet with an average surface crater retention age of ~500 Ma (Strom et al., 1994; McKinnon et al., 1997). Thus, tesserae provide the best and perhaps only chance to access rock...

A decline in radar emissivity at many Venus mountaintops (Klose et al., 1992; Pettengill et al., 1992) is thought to be the result of atmosphere-surface interactions in the highlands, where temperatures are lower (Arvidson et al., 1994; Shepard et al., 1994; Brackett et al., 1995). These reactions are a function of rock composition, atmospheric com...

Spatial trends seen in Magellan data (λ = 12 cm) indicate differences in the composition of volcanoes, coronae, tesserae and mountain belts and possibly in the weathering rates and processes across these landscapes (Brossier et al., under review; Brossier and Gilmore, in prep.). Radar emissivity and elevation data reveal distinct patterns in emissi...

Multiple studies reveal that most of Venus highlands exhibit anomalously high radar reflectivity and low radar emissivity relative to the lowlands. This phenomenon is thought to be the result of atmosphere-surface interactions in the highlands, due to lower temperatures. These reactions are a function of rock composition, atmospheric composition, a...

Tessera terrain are the stratigraphically oldest materials on Venus, predating the volcanic plains that cover the majority of the planet. A revised estimate of the surface crater age of the tesserae may be as old as 1.75 Ga, which overlaps with models that predict a more clement Venus during the first 2-3 Ga of Venus history (Way et al., 2016); the...

We characterize how emissivity varies with altitude on Venus major volcanoes and coronae to constrain their relative composition and age. This tends to better understand the radar anomalies seen across Venus highlands.

Previous work attempting to model the causes in Magellan 12.6 cm radar properties at high elevations have considered the cumulative emissivity of all surfaces (Klose et al., 1992; Pettengill et al., 1992; Tryka and Muhlman, 1992; Shepard et al., 1994; Brackett et al., 1995; Pettengill et al., 1996; Treiman et al., 2016), without exploring potential...

Several studies (Klose et al., 1992; Pettengill et al., 1992) have recognized that many of the Venusian highlands display anomalous decreases in radar emissivity. This phenomenon is thought to be the result of atmosphere-surface interactions in the highlands, and hence at lower temperatures (e.g., Arvidson et al., 1994; Shepard et al., 1994; Treima...

In the early 90s, NASA’s Magellan radar images revealed a Venusian surface with an average crater age of ~ 500 Ma (Strom et al., 1994; McKinnon et al., 1997) that can be broadly divided into three major types of terrain involving three chronological eras of Venus’ history based on their stratigraphic position. First, the heavily deformed plateaus n...

Several authors (Klose et al., 1992; Shepard et al., 1994; Treiman et al., 2016) observe reductions in radar emissivity at high altitudes (>2.5 km above MPR of 6051.8 km) on volcanoes that are best explained by changes in mineral compositions at these locations. The presence of ferroelectric or semiconductor materials are possible explanations for...

The structurally deformed Venus tessera terrain covers about ~8% of the surface of Venus and consistently appears locally and perhaps even globally (Ivanov and Head, 1996) as the stratigraphically oldest material on a planet with an average surface crater retention age of ~300 - 800 Ma (Strom et al., 1994; McKinnon et al., 1997). Thus, the tesserae...

During thirteen years (2004-2017), the Cassini-Huygens mission revealed that Titan is is a frozen version of Earth, where methane behaves as water, organic matter as sediment, and where water ice may be as hard as rock. Consequently, Titan experiences a large variety of surface processes that involve exchange between its surface and its atmosphere....

In thirteen years, infrared observations from the Visual and Infrared Mapping Spectrometer (VIMS) onboard the Cassini orbiter have provided significant hints about the spectral and geological diversity on Titan's surface, the largest moon of Saturn. The analysis of the infrared signature of spectral units enables constraining the surface compositio...

In thirteen years, infrared observations from the Visual and Infrared Mapping Spectrometer (VIMS) onboard Cassini provided significant hints about the spectral and geological diversity of Titan’s surface. The analysis of the infrared signature of spectral units enables constraining the surface composition, which is essential to understand possible...

Recent mineralogical studies suggest the presence of an iron chlorine hydroxide, namely akaganeite. This mineral is known to form under specific conditions, and it has been detected in the Robert Sharp Crater, located at Mars’ low-latitudes (133.59˚E, -4.12˚N) [1]. Its detection implies an acidic and oxidizing environment in this region. Indeed, ak...

In thirteen years, infrared observations from the Visual and Infrared Mapping Spectrometer (VIMS) onboard Cassini provided significant hints about the spectral and geological diversity of Titan's surface. The analysis of the infrared signature of spectral units enables constraining the surface composition, which is crucial for understanding possibl...

We investigate Titan's low- and mid-latitude surface using spectro-imaging near-infrared data from Cassini/VIMS. We use a radiative transfer code to first evaluate atmospheric contributions and then extract the haze and the surface albedo values of major geomorphological units identified in Cassini Synthetic Aperture Radar data, which exhibit quite...

Over these past thirteen years, near-IR imaging data from the Visual and Infrared Mapping Spectrometer (VIMS) onboard Cassini gave significant hints on the spectroscopic and geological diversity of the terrains on Titan's surface. The composition of those terrains still remains unconfirmed yet. Nonetheless, by applying a newly updated radiative tra...

Since twelve years of exploration, near-infrared imaging data provided from the Visible and Infrared Mapping Spectrometer (VIMS) onboard Cassini reveal a variety of surface units that are compositionally and/or structurally distinct. The analysis of these units enables constraining the surface composition of Titan, which is of prime importance for...

Since eleven years of observation, near-infrared imaging data from Visual and Infrared Mapping Spectrometer (VIMS) onboard Cassini reveal a variety of surface units that are compositionally and structurally distinct. The analysis of these units enables constraining the surface composition of Titan, which is of prime importance for modeling Titan’s...

From about eleven years, optical and microwaves imaging instruments are unveiling the surface of the intriguing and biggest Saturn’s moon, Titan. The strong spatial resolution of the radar instrument (up to 170 m/px) and its insensitivity to atmospheric scattering effects [1], as well as the high resolution of the Imaging Science Subsystem camera (...

Since the equatorial regions of Titan have been fully observed by the Visible and Infrared Mapping Spectrometer (VIMS) [1], the analysis of false-color composites enables distinguishing four main spectral units: the equatorial bright, brown, blue, and 5 μm-bright spectral units [2-4]. More precisely, the equatorial bright plateaus and inselbergs co...

Since the equatorial regions of Titan have been fully observed by the Visible and Infrared Mapping Spectrometer (VIMS) [1], the analysis of false-color composite allows distinguishing three mains units: bright, bluish and brownish units [2-4]. This distinction can be enhanced by using ratios of VIMS channels that allow emphasizing subtle difference...

According to recent mineralogical study, the presence of an iron oxi-hydroxide (akaganéite) which form under specific conditions, has been detected in Robert Sharp crater, located in the equatorial region of Mars (133.59°'E, -4.12°N), implying an acidic and oxidizing environment in this region. These deposits of akaganéite might be the ultimate alt...