A lost ocean? Lava under Mount Olympus?

View larger. | Gravity map of Mars showing dense gravitational structures beneath the surface of the red planet in its northern hemisphere. The regions indicated by the black lines are high mass. anomalies below the surface of Mars, that is, different, abnormal or difficult to classify places. They do not appear to correlate with known Martian geology and topography. Image via Root et al./ Europlanet Society.

Mars gravity map: sphere speckled with blue and brown spots. Some brown spots have a black outline. — View larger. | Gravity map of Mars showing dense gravitational structures beneath the surface of the red planet in its northern hemisphere. The regions indicated by the black lines are high mass. anomalies below the surface of Mars, that is, different, abnormal or difficult to classify places. They do not appear to correlate with known Martian geology and topography. Image via Root et al./ Europlanet Society.

Mars is geologically rich beneath its surface. It has extensive deposits of ice and perhaps even liquid water in its depths. What else is underground on Mars?
Scientists have found about 20 “structures” below the surface of Mars. They are denser than the surrounding rock and are buried under a thick layer of sediment in the planet's northern hemisphere. The sediment could come from an ancient ancient ocean on Mars.
A huge pool of lava It could also be found beneath Olympus Mons, the largest volcano on Mars. Lava appears to be rising toward the surface of Mars.

Surprises from a new gravity map of Mars

Scientists have discovered multiple dense features or large-scale “structures” beneath the northern hemisphere of Mars. The massive structures are buried beneath a soft layer of sediment, which scientists believe comes from an ancient ancient ocean. Additionally, there is also evidence of active processes, possibly lava, beneath Mount Olympusthe largest volcano on Mars. Researchers at Delft University of Technology (TU Delft) in the Netherlands saying on September 13, 2024, they made the findings using a new gravity map of Mars, with data from multiple missions to Mars.

The researchers, led by Bart's root from TU Delft, presented their findings at the Europlanet 2024 Scientific Congress earlier this month. You can read the summary. here.

Studies of gravity variations on Mars have revealed dense, large-scale structures hidden beneath the sediment layers of a lost ocean. The findings have been presented in the #EPSC2024 by Bart Root @tudelft: https://t.co/6Y9F5XBkAS pic.twitter.com/dLPNaNVtBb

—Europlanet? (@europlanetamedia) September 13, 2024

Features hidden beneath Mars' buried ocean sediments?

The dense structures are found in the northern hemisphere of Mars, in the planet's crust. They are significantly denser than other surrounding rocks. Additionally, they lie beneath a thick, soft layer of sediment. The researchers said this sediment likely came from an ancient ancient ocean in the northern hemisphere of Mars. This is something that scientists have also discussed and debated for decades.

In total there are about 20 unusual structures of different sizes. They are about 300 to 400 kg/m3 (kilograms per cubic meter/19 to 25 pounds per cubic foot) denser than the surrounding rock. So what are they? as root explained:

These dense structures could be of volcanic origin or could be material compacted due to ancient impacts. There are around 20 features of different sizes that we have identified spread across the area surrounding the north polar cap, one of which resembles the shape of a dog.

The anomalies are completely buried and there are no signs of them on the Martian surface. Added root:

There seems to be no trace of them on the surface. However, through the gravity data, we have a tantalizing glimpse into the earliest history of Mars' northern hemisphere.

View larger. | Topographic map showing subsurface anomalies clustered around the north pole, outlined in black. Image via Root et al./ Europlanet Scientific Congress (CC BY 4.0).

Discovery of anomalies.

So how did the researchers find these unusual features? They created a gravity map of Mars by observing small deviations in the orbits of spacecraft around the planet. The researchers analyzed those deviations for clues about the internal structure and mass distribution of Mars. Gravitational variations within Mars can show differences in the density of any subsurface geological structure.

Meanwhile, NASA InSight lander The mission had studied the Martian crust, including its thickness and flexibility. The research team combined data from InSight with data from the orbiters in a new computer model. In addition, they included data from the depths of the Mars mantle. The resulting gravity map revealed the location of the dense structures beneath the surface.

Lava below Mount Olympus?

Furthermore, apart from the dense anomalies, the map showed something else. He tarsis The region is a huge volcanic plateau, which includes Olympus Mons, the largest volcano on Mars. Scientists knew that a region of weaker gravity and lower density surrounds the plateau. But why? The new map provided some clues. There is a huge mass of lighter material beneath it, about 1,740 kilometers (1,080 miles) wide and 1,095 kilometers (680 miles) deep. The researchers said this material could explain why Tharsis has a much higher elevation than the surrounding terrain.

In fact, according to the new study, that material could be lava. It is moving toward the surface, causing upwelling. Root saying:

NASA's InSight mission has given us vital new information about the tough outer shell of Mars. This means that we must rethink how we understand the support of the Olympus Mons volcano and its surroundings. It shows that Mars could still have active movements within it, affecting and possibly creating new volcanic features on the surface.

View larger. | Global gravity map from Mars. Red circles show prominent volcanoes and black circles show impact craters with a diameter greater than about 62 miles (100 km). He tarsis The region is the large red area in the center right. It is surrounded by an unusual large ring of weaker gravity, in blue. Image via Root et al./ Europlanet Society.

Martian quantum gravity mission

Determining exactly what the subsurface structures are will require a follow-up mission. That is where the Martian Quantum Gravity proposal arises (MaQuls) the mission arrives. It will study variations in gravity and use some of the same technology as the GRAIL and FUNNY missions. GRAIL studied the Moon's gravitational field, while GRACE measured Earth's gravitational field and more.

Lisa Wörner at the German Aerospace Center (DLR) saying:

Observations with MaQuIs would allow us to better explore the subsurface of Mars. This would help us find out more about these mysterious hidden features and study them in progress. mantle convectionin addition to understanding dynamic surface processes, such as atmospheric seasonal changes and the detection of groundwater deposits.

Bottom line: A new gravity map of Mars shows strange structures hidden beneath the surface of Mars. Some could be related to an ancient ocean. Others could be lava!

Source: Exploration of high-mass subsurface structures in the Northern Hemisphere with co-bending and mantle convection modeling of the Martian gravitational field.

Through the Europlanet Society

Paul Scott Anderson

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About the author:

Paul Scott Anderson has had a passion for space exploration that began as a child watching Carl Sagan's Cosmos. He studied English, writing, art, and computer and publishing design in high school and college. He later started his blog The Meridiani Journal in 2005, which was later renamed Planetaria. Later he also started the blog Fermi Paradoxica, about the search for life in other places in the universe. While he is interested in all aspects of space exploration, his primary passion is planetary science and SETI. In 2011, he began writing about space independently at Universe Today. He has also written for SpaceFlight Insider and AmericaSpace and has also been published in The Mars Quarterly. He also did some supplementary writing for the Exoplanet iOS app. He has been writing for EarthSky since 2018 and also helps with testing and social media.