09-23-2024

Mars gravity map exposes ancient structures and volcanic activity

Earth.com staff writer

New data on the weighty subject of gravity on Mars is shedding light on the planet’s hidden structures and providing fresh insights into the volcanic activity that gave rise to Olympus Mons, the largest volcano in our Solar System.

The study explores the thick sediment layers that once formed Mars’ lost oceanic landscape to uncover the secrets of our neighboring planet.

Gravity data and Mars’ hidden structures

Despite its barren and rugged appearance, Mars hides a world of mystery beneath its red soils.

Until recently, scientists could only hypothesize about the complexities of Martian topography shrouded beneath layers of sediment.

However, a game-changing analysis blending data from multiple sources, including the NASA InSight Lander mission, has unveiled intriguing anomalies in the gravity field of Mars — revealing the existence of dense, large-scale formations beneath the northern polar plains.

Dr. Bart Root of Delft University of Technology (TU Delft) presented the findings of this study at the Europlanet Science Congress (EPSC) in Berlin.

Gravity map of Mars. The red circles show prominent volcanoes on Mars and the black circles show impact crates with a diameter larger than a few 100 km. A gravity high signal is located in the volcanic Tharsis Region (the red area in the centre right of the image), which is surrounded by a ring of negative gravity anomaly (shown in blue). Credit: Root et al.

“These dense structures could be volcanic in origin or could be compacted material due to ancient impacts. There are around 20 features of varying sizes that we have identified dotted around the area surrounding the north polar cap — one of which resembles the shape of a dog,” explained Dr. Root.

“There seems to be no trace of them at the surface. However, through gravity data, we have a tantalizing glimpse into the older history of the northern hemisphere of Mars.”

The features, engulfed in an air of mystery, are hidden beneath a thick, smooth sedimentary blanket believed to have been part of an ancient seabed. Interestingly, these structures could be volcanic remnants or compacted materials resulting from ancient impacts.

Piecing together the Martian puzzle

Researchers from TU Delft and Utrecht University employed deviations in the orbits of satellites to investigate the gravity field of Mars and unearth hints about the planet’s interior mass distribution.

This data, fed into models utilizing observations from NASA’s InSight mission, provided new insights into the thickness and flexibility of the Martian crust and the dynamics of the mantle.

The result was an unprecedented global density map of Mars.

The density map revealed that the northern polar formations are approximately 300-400 kg/m³ denser than their surroundings.

“Through gravity data, we have a tantalizing glimpse into the older history of the northern hemisphere of Mars,” Dr. Root added.

The study also unmasked previously unknown details about the structures underlying the enormous volcanic region of Tharsis Rise, including Olympus Mons.

Mars’ gravity map and volcanic conundrum

Although volcanoes are typically dense, the Tharsis region is unusually elevated compared to Mars’ average surface and is encapsulated by a comparably weak gravity area.

This gravity anomaly raises questions about the contrast in the Martian crust and upper mantle.

“The NASA InSight mission has given us vital new information about the hard outer layer of Mars. This means we need to rethink how we understand the support for the Olympus Mons volcano and its surroundings,” said Dr. Root.

Map highlighting the dense gravitational structures in the northern hemisphere. The regions denoted by the black lines are high mass anomalies that do not show any correlation with geology and topography. These hidden subsurface structures are covered by sediments from an old ocean. Their origin is still a mystery and a dedicated gravity mission, like MaQuIs, is needed to reveal their nature. Credit: Root et al.

The study suggests that a light mass about 1,750 kilometers wide, sitting at a depth of 1,100 kilometers, is exerting an upward push on the entire Tharsis region.

This could be the result of a massive plume of liquid rock deep within Mars’ core, rising towards the surface.

“It shows that Mars might still have active movements happening inside it, affecting and possibly making new volcanic features on the surface,” added Dr. Root.

Martian Quantum Gravity (MaQuIs) mission

Looking towards the future, the research team is proposing the Martian Quantum Gravity (MaQuIs) mission.

Dr. Lisa Wörner of the German Aerospace Center (DLR) presented on the MaQuIs mission at EPSC2024.

“Observations with MaQuIs would enable us to better explore the subsurface of Mars. This would help us to find out more about these mysterious hidden features and study ongoing mantle convection, as well as understand dynamic surface processes like atmospheric seasonal changes and the detection of groundwater reservoirs,” explained Dr. Wörner.

The mission, which aims to map Mars’ gravity field in unprecedented detail, is adapted from technology used in GRAIL and GRACE missions on the Moon and Earth, respectively.

Clearly, we still have a lot to learn about the Red Planet, especially if humans plan on living there one day.

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