Mars' Tharsis region and Valles Marineris imaged by Mars Express HRSC. This image, taken shortly after the northern hemisphere's summer solstice, captures the planet's Aphelion Cloud Belt near peak density. The cloud belt forms when the planet is furthest from the Sun, when lower atmospheric temperatures cause the condensation temperature for water ice crystals to fall to altitudes with more water vapor. The aphelion cloud belt is generally thickest over the high terrain of the Tharis volcanic region.
Olympus Mons is visible at far left, near the horizon. A small windstorm is present near its summit, lifting large dust clouds. A large orographic cloud is visible on the western slopes of Ascraeus Mons (top left/center). Pavonis Mons (left center) and the northern flanks of Arsia Mons are visible in a line just below it.
The large canyon system of Valles Marineris dominates the left side of the image. This gigantic canyon system formed due to the immense weight of the large shield volcanoes to its west. The weight of these volcanoes pushes down on the planet's interior, causing the landscape to swell and buckle in the region of Valles Marineris.
This image was taken during Mars Express' 24,725th orbit of Mars, on August 1, 2023.
Image Credit: ESA / DLR / FU Berlin / A. Cowart, CC BY-SA 3.0 IGO
Tags: Mars Mars Express HRSC Valles Marineris Noctis Labyrinthus Olympus Mons Ascraeus Mons Pavonis Mons Tharsis
Mars Express HRSC image of icy winds descending up to 2 km from Ultima Lingula, a buried "tongue" of Mars' south polar ice cap. The winds are driven by intense sublimation of the winter carbon dioxide ice deposits as the south pole neared its summer solstice. Wind gusts are lifting dust clouds which are moving in a generally northerly direction. The dust is blocked by a kilometer high ridge, part of a series of escarpments known as Thyles Rupes, causing the lifted dust to drift west (towards image bottom) along the ridgeline.
Remnant frost is visible in the shadowed sides of dark sand dunes at top left, and in the rugged terrain near image center. Erosion and sublimation along the edge of Ultima Lingula at top right have revealed alternating ice and dust rich layers, forming swirly features in the landscape.
This image was taken during Mars Express' 23,290th orbit of the red planet, June 9, 2022.
Image Credit: ESA / DLR / FU Berlin / A. Cowart, CC BY-SA 3.0 IGO North is at left, image scale ~15 m/px.
Tags: Mars Mars Express HRSC Ultima Lingula ESA space
Three frame left Navcam mosaic looking back on Marker Band Valley, taken by the rover on Sol 3778 (March 23, 2023).
The Marker Band is a thin (1-5 m thick) horizon within Mt. Sharp which extends laterally for 10s of kilometers. During its exploration of the Marker Band, Curiosity observed ripple beds, consistent with deposition in a lake. A particularly large outcrop of the Marker Band forms the flat, dark plain at center-right. Rocks overlying the Marker Band are thinly layered, and have been shaped by erosion into fantastic shapes.
Marker Band Valley is flanked by several large buttes which have been named. The pointy butte at left center was named Amapa, the haystack buttes at center Bolivar and Deepdale, and the layered hill to the right is named Chenapau.
Image Credit: NASA / JPL / Aster Cowart
Tags: Gale Crater Marker Band Marker Band Valley Curiosity Mars space NASA
A view up Gediz Vallis from the Curiosity's location on Sol 3646 (November 8, 2022). This photo captures the rover's eventual direction of travel up into Gediz Vallis.
NASA/ JPL-Caltech / Malin Space Science Systems / Aster Cowart
Tags: Gediz Vallis Mt Sharp Gale Crater Mars Curiosity
Mars Express HRSC image of the Isidis Basin/Syrtis Major Planum region. The Isidis Basin measures ~1500 km in diameter and has heavily shaped the geomorphology of the surrounding region. The large concentric canyons on its northwestern rim (center left), named Nili Fossae, were created by the slumping of crust back into the initial transient crater created by the impact. Later, this region was subject to intense pyroclastic volcanism that left olivine-rich rocks distributed over more than 100,000 sq. km. of the surface. The olivine reacted with water present on the ancient Martian surface to form carbonate and serpentine group minerals, a heat-producing reaction that likely generated long-lived hydrothermal systems. Jezero Crater contains portions of this extensive deposit, in addition to evidence for a lake system. These aspects make it among the best candidates for the formation of Martian life, leading to Jezero's selection for the Perseverance mission.
The western edge of Isidis is also marked by the large volcanic plains of Syrtis Major Planum. Large volcanic plains like this are commonly found around large impact basins on Mars, suggesting the impacts may play some role in their formation. The substantial crustal thinning and deep fracturing caused by an impact likely make it easier for magma to ascend to the surface and erupt. Over time, the lava erupted in this region changed as the source magma's composition evolved. This caused the lava flows to evolve from silica-poor (which tend to be hot and runny) to more silica rich (which tend to be more explosive). Nili Patera, a ~50 km wide volcanic crater located near bottom center, represents the last stages of this evolution. Rock compositions here show a greater variety in silica content than at any other location on the Martian surface.
The southern rim of the basin is marked by the high mountains of Libya Montes. This region appears to have experienced volcanism as well, but to a far lesser extent than at Nili Fossae or Syrtis Major Planum. To date, only large cinder cones have been identified in this region. Most mountains here appear to be large fragments of crust ejected from the basin or dredged up by the upwards and outwards force of the impact's excavation. As a result, these mountains have been suggested as a geological laboratory for exploring the contents of the deep Martian subsurface.
Larger forces are also seen in this photo. There is a dramatic difference between Mars' northern lowlands and southern highlands regions. The lowlands, located at left, are only lightly cratered, likely either due to sediments deposited in a now-dried ocean basin, or through intense volcanic activity that occurred later in the planet's history. This low region is separated from the highlands by an extensive escarpment that circles nearly 2/3 of the planet. Here, the escarpment is named Nilosyrtis Fossae. The Nilosyrtis Fossae escarpment is especially tall, likely due to the presence of deep fractures created by the Isidis Basin.
The southern highlands instead represent some of the most ancient terrain still present on the Martian surface. Much of this region dates to between 4.1 and 3.8 billion years old. Although this region contains many craters, a close look reveals that many of them are shallow and highly degraded. This shows that Mars was geologically active during its early history, as water, ice, and volcanic activity attempted to infill the craters at a rate not much slower than the craters could form.
This image was taken from an altitude of ~19,500 km during Mars Express' 21,718th orbit of the red planet, March 9, 2021.
Image Credit: ESA/DLR/FU Berlin/A. Cowart, CC BY-SA 3.0 IGO
Tags: Mars Express HRSC Mars Isidis Basin Syrtis Major Planum Jezero Crater globe ESA space