A team of scientists presented a new gravity map of Mars at the Europlanet Science Congress 2024. The map shows the presence of dense, large-scale structures under Mars\u2019 long-gone ocean and that mantle processes are affecting Olympus Mons, the largest volcano in the Solar System. <\/p>\n
<\/p>\n The new map and analysis include data from multiple missions, including NASA\u2019s InSIGHT (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) mission. They also use data from tiny deviations in satellites as they orbit Mars. The paper \u201cThe global gravity field of Mars reveals an active interior\u201d will be published in an upcoming edition of JGR: Planets. The lead author is Bart Root of the Delft University of Technology. Some of the results go against an important concept in geology.<\/p>\n Geologists work with a concept called flexural isostasy. It describes how a planet\u2019s outer rigid layer responds to large-scale loading and unloading. The layer is called the lithosphere and consists of the crust and the uppermost part of the mantle. When something heavy loads the lithosphere, it responds by sinking. On Earth, Greenland is a good example of this, where the massive ice sheet puts downward pressure on it. As its ice sheets melt due to global warming, Greenland will rise. <\/p>\n This downward bending often causes an uplift in surrounding areas, though the effect is slight. The more massive the load is, the more pronounced the downward bending, although it also depends on the lithosphere\u2019s strength and elasticity. Flexural isostasy is a critical idea for understanding glacial rebound, mountain formation, and sedimentary basin formation. <\/p>\n The authors of the new paper say scientists need to rethink how flexural isostasy works on Mars. This is because of Olympus Mons, the largest volcano in the Solar System, and the entire volcanic region called Tharsis Rise, or Tharsis Montes. Tharsis Montes is a vast volcanic region that holds three other enormous shield volcanoes: Arsia Mons, Pavonis Mons, and Ascraeus Mons.<\/p>\n Flexural isostasy states that this massive region should force the planet\u2019s surface downward. But the reverse is true. Tharsis Montes is much more elevated than the rest of Mars\u2019 surface. NASA\u2019s InSIGHT lander also told scientists a lot about Mars\u2019 gravity, and together, it\u2019s forcing researchers to reconsider how this all works on Mars. <\/p>\n \u201cThis means we need to rethink how we understand the support for the big volcano and its surroundings,\u201d the authors write. \u201cThe gravity signal of its surface fits well with a model that considers the planet as a thin shell.\u201d<\/p>\n The research shows that active processes in the Martian mantle are boosting Tharsis Montes upward. \u201cThere seems to be a big mass (something light) deep in Mars\u2019 layer, possibly rising from the mantle,\u201d the authors write. \u201cIt shows that Mars might still have active movements happening inside it, making new volcanic things on the surface.\u201d<\/p>\n The researchers found an underground mass around 1750 kilometres across and at a depth of 1100 kilometres. They suspect that it\u2019s a mantle plume rising under Tharsis Montes and strong enough to counteract the downward pressure from all the mass. \u201cThis suggests that a plume head is currently flowing upward towards the lithosphere to generate active volcanism in the geological future,\u201d the authors write in their paper. <\/p>\n There\u2019s debate about how volcanically active Mars is. Although there are no active volcanic features on the planet,\u00a0research <\/span>shows\u00a0that the Tharsis region has\u00a0resurfaced in the near geological past within the last few tens of millions of years. If there is a mantle plume under Tharsis Montes, could it eventually reach the surface? That\u2019s purely speculative, and more research is needed to confirm these findings. <\/p>\n The researchers also found other gravitational anomalies. They found mysterious, dense structures under Mars\u2019 northern polar plains. They\u2019re buried under a thick, smooth sediment layer that was likely deposited on an ancient seabed. <\/p>\n The anomalies are approximately 300\u2013400 kg\/m3 denser than their surroundings. Earth\u2019s Moon has gravitational anomalies that are associated with giant impact basins. Scientists think that the impactors that created the basins were denser than the Moon, and their mass has become part of the Moon. <\/p>\n Impact basins on Mars also show gravity anomalies. However, the anomalies in Mars\u2019 northern hemisphere show no traces of them on the surface.<\/p>\n \u201cThese 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\u2014one of which resembles the shape of a dog,\u201d said Dr. Root. \u201cThere seems to be no trace of them at the surface. However, through\u00a0gravity data, we have a tantalizing glimpse into the older history of the northern hemisphere of Mars.\u201d <\/p>\n The only way to understand these mysterious structures and Mars\u2019 gravity in general is with more data. Root and his colleagues are proponents of a mission that could gather the needed data. <\/p>\n It\u2019s called the Martian Quantum Gravity (MaQuls) mission. MaQuls would be based on the same technology used in the GRAIL (Gravity Recovery and Interior Laboratory) and GRACE (Gravity Recovery and Climate Experiment) missions, which mapped the Moon\u2019s and Earth\u2019s gravity, respectively. MaQuls would feature two satellites trailing each other and connected by an optical link. <\/p>\n \u201cObservations 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 ground water reservoirs,\u201d said Dr. Lisa W\u00f6rner of DLR, who presented on the MaQuIs mission at EPSC2024 this week.<\/p>\n![\"This](\"https:\/\/www.universetoday.com\/wp-content\/uploads\/2024\/09\/gravity-study-gives-in-1-1-1024x566.jpg\")
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