A research group presented a new gravity map of Mars at the Europlanet Science Congress 2024 in Berlin. The map shows one Contradiction to common concepts in geology and mysterious structures under the long-vanished ocean of the celestial body.
Different gravity affects Mars probes
The new map contains data several Mars missions. Gravity maps allow researchers to virtually… To look inside a planet and thus to put forward theses about its composition. They are created using space probes that orbit a planet – in this case Mars.
These space probes are attracted to different regions of Mars to different degrees. The gravitational pull over a mountain is roughly stronger than over a gorge. The slight differences in gravity change it trajectory of the probes is small – but enough to measure it and draw conclusions about gravity.
Martian volcanoes contradict geological concepts
Some of the research group’s results contradict an important concept in geology called Isostasy. The concept states that the outer layer of a planet is formed by the action of a sinks in with great weight. The downward weight often causes surrounding areas to rise slightly as well.
If this weight is lost again, the planet’s crust is flexible enough to spring back to its original shape. An example on Earth is Greenland, which exerts downward pressure through its ice sheets. As the ice sheets melt due to global warming, Greenland is rising.
According to the researchers, however, this concept needs to be reconsidered on Mars. The reason is the largest volcano in the solar system Olympus Mons (22 km altitude) or the volcanic area around it, in which there are 3 other gigantic volcanoes.
According to isostasy, these mountains should be the surface of the planet press down – but the opposite is the case. The region is much higher than the rest of the Martian surface. According to the researchers, this means that active processes in the mantle of Mars drive the mountains up.
“There appears to be a large mass (something light) deep in the Martian layer that may be rising from the mantle,” . “This shows that Mars still has active movements within its interior that are creating new volcanic things on the surface.”
How volcanically active Mars is is controversial. Although there are no active volcanoes on the planet, data points to one Mantelplume in the area beneath Olympus Mons – i.e. rising material that could potentially reach the surface. However, it is still unclear whether and when this will be the case.
Mysterious structures at the North Pole
In addition, the researchers found mysterious structures underneath northern polar plains of Mars. There are areas beneath the former seabed whose rock is significantly denser than that of the surrounding area.
“These dense structures could be volcanic in origin or made of compacted material created by previous impacts. We have identified about 20 structures of different sizes around the North Polar cap – one of which is similar to this one Shape of a dog“says researcher Bart Root.
The only way to better understand these structures is to collect more data, the researchers say. Root and his colleagues are therefore supporters of the Martian Quantum Gravity Mission – a mission concept in which the gravity of Mars is to be measured more precisely.
The mission involves two satellites orbiting Mars one after the other, measuring the distance to each other using an optical laser. If the first satellite is attracted more strongly by gravity than the second, this distance increases. This means that gravitational anomalies on the planet can be detected much more precisely.
