New Images of Mars Reveal Chasms on the Flanks of a Martian Volcano

Dramatic features are visible across the frame, many of which overlap and knit together: lava flows and tubes, chains of craters, channel-like rilles and large fissures, all resembling irregular depressions and grooves in the tan-coloured surface. These are collectively named Ascraeus Chasmata, and encompass an enormous patch of collapsed terrain over 70 km across.  Credit: ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO

Mars, often referred to as the Red Planet, boasts some of the most remarkable volcanic formations in our solar system. Recently, the European Space Agency's Mars Express mission has provided captivating images of the pitted and fissured flanks of Ascraeus Mons, Mars' second tallest volcano. These observations, captured by the mission's High-Resolution Stereo Camera (HRSC), reveal a landscape filled with dramatic chasms, lava flows, craters, and fissures, forming an otherworldly tapestry of geological wonders. This article explores the awe-inspiring features found on Ascraeus Mons, shedding light on their formation and contributing to our understanding of Mars' volcanic activity.

Ascraeus Mons: A Geological Marvel 

Ascending to an astounding height of 18 kilometers, Ascraeus Mons stands as the tallest volcano in the Tharsis region of Mars. Situated in Mars' western hemisphere, this massive volcano possesses a gentle slope with an average incline of 7 degrees. With a base diameter spanning an impressive 480 kilometers, roughly the size of Romania on Earth, Ascraeus Mons commands attention as one of the most significant landmarks on the Martian surface. Surpassed only by Olympus Mons, the largest volcano in the solar system, Ascraeus Mons is a testament to the dynamic geological history of Mars.

A Mosaic of Chasms: Ascraeus Chasmata 

The Mars Express images reveal a fascinating patchwork of collapsed terrain known as Ascraeus Chasmata. Spanning over 70 kilometers, these chasms encompass a diverse range of features, including lava flows, tubes, craters, rilles, and expansive fissures. These elements, varying in age and origin, combine to create a mesmerizing landscape reminiscent of ink dispersing in water or the intricate root system of a plant delving into soil.

Unraveling the Mysteries of Martian Geology 

The captivating imagery captured by Mars Express offers scientists a unique opportunity to study the geological processes at work on Mars. On the lower southern flank of Ascraeus Mons, a stark contrast in elevation is evident, with the left (southern) side of the frame situated approximately 10 kilometers lower than the right (northern) side. The summit of the volcano is located to the right of the frame, as highlighted by a wider context map of the region.

Wrinkled lava flows and pit craters dominate the right side of the frame. These crinkled lava flows encounter chains of pit craters, where circular or near-circular depressions have merged to form troughs. Similar features can be found on Earth, such as the striking Cenotes in Mexico's Yucat√°n Peninsula. These pit crater chains and troughs likely result from hidden voids beneath the surface, causing instability and collapse, resembling sinkholes. These subsurface voids are believed to form as the surface layer of a lava flow rapidly cools and hardens, while the underlying lava gradually drains away, leaving tube-shaped pockets of empty space several meters below the ground.

To the left of the pit crater chains, sinuous rilles carve through the terrain. These sinuous channels, lacking rims, are often found on the flanks of volcanoes. Their exact formation mechanisms remain uncertain, but theories suggest a combination of lava, ash, and water flows playing a role in shaping these snaking channels.

The leftmost section of the image reveals expansive fissures, measuring up to 40 kilometers in length. From these fissures, channels emerge, intertwining and braiding together, creating braided channels that isolate chunks of Martian terrain, forming islands and terraces. These unique features are believed to have formed through the action of water, possibly as snow and ice accumulated on the flanks of Ascraeus Mons before eventually melting away.

Exploring Mars with Mars Express 

Since its arrival at Mars in 2003, the Mars Express mission has been diligently studying the Red Planet's surface, atmosphere, and subsurface. The mission's High-Resolution Stereo Camera (HRSC) has played a crucial role in capturing detailed images of Mars' diverse features, including wind-sculpted ridges, impact craters, tectonic faults, river channels, and ancient lava pools. Ascraeus Mons, with its intriguing volcanic formations, has become a subject of great interest for scientists aiming to unravel the geological mysteries of Mars.

The HRSC images of Ascraeus Mons and its surrounding region provide valuable insights into the planet's volcanic history. By analyzing the composition and morphology of the lava flows, craters, and fissures, scientists can gain a better understanding of the volcanic processes that have shaped Mars over millions of years. These findings contribute to our knowledge of how different phenomena interact in the Martian environment and provide clues about the planet's past habitability.

Additionally, the images reveal the presence of potential subsurface voids and hidden channels beneath the surface of Ascraeus Mons. These underground features hold significant scientific value as they offer insights into the planet's subsurface hydrological processes and the possibility of past water-related activity.

Looking Ahead

As Mars Express continues its mission, scientists eagerly anticipate further discoveries and insights into the complex geology of Mars. The mission's ongoing exploration of Ascraeus Mons and other volcanic features will shed light on the planet's volcanic activity and its implications for the Martian climate and habitability.

Future missions, such as NASA's Mars Sample Return campaign, will aim to bring back physical samples from Mars for detailed laboratory analysis on Earth. These samples, potentially including volcanic rocks from Ascraeus Mons, will provide an unprecedented opportunity to study the planet's geology and gain a deeper understanding of its volcanic history.

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