The researchers found that the density of the core was surprisingly low, only about 6 grams per cubic centimeter, which is much lower than what they expected from a center rich in iron. “It’s still a bit of a mystery how the core is so light,” Stähler says. Lighter elements must be present, although it is true that they may be unclear. He and his team eventually hope to discover P-waves produced by marshmallows originating directly from the planet from where InSight is parked. Because they can penetrate the core-sheath boundary, it will transmit core composition information to the landing receiver. But for that to happen, Stähler says, “Mars has to play around and give us this earthquake on the other side of the planet.”
In a Stähler team article, they report a core radius of 1,830 kilometers. Another team, led by Zurich-based geophysicist Amir Khan, found that this size is so large that it leaves little room for an Earth-like lower mantle, a layer that acts as a cover that traps heat around the core. The earth’s mantle is divided into two parts, and between them is the so-called transition zone; the upper and lower levels consist of different minerals. “The March mantle is – I can say lightly – a slightly simpler version of the Earth’s mantle, simply in terms of mineralogy,” says Khan, the lead author of the paper describing the mantle.
Previous estimates of core radius using geochemical and geophysical data suggested the absence of a lower mantle, but scientists needed InSight seismic readings to confirm this. Without this layer, the Martian core would probably have cooled much easier than Earth’s. This is key to understanding the evolution of the Red Planet, and especially why it has lost its magnetic field, a barrier that would protect the atmosphere – and potential life – from harsh solar winds. The creation of a magnetic field requires a temperature gradient between the outer and inner core, high enough to create circulating currents that repel the fluid of the core and create a magnetic field. But the core cooled so fast that those convection currents died out.
Khan’s analysis also shows that Mars has a dense lithosphere, a solid and a cold part of the mantle. This could be a clue as to why the Red Planet does not have the plate tectonics that drives the frenzy of volcanism on Earth. “If you have a very dense lithosphere, it will be very difficult to break this thing up and create the exact equivalent of plate tectonics on Earth,” Khan says. “Mars may have had it very early, but it’s safely shut down now.”
As InSight eavesdrops on the inner vibrations of Mars, Perseverance rolled around its dusty surface looking for signs of ancient life in the rocks, digging places to collect regolith samples and learning about the lake’s geological history. “Research is not a sprint, it’s a marathon,” said Thomas Zurbuchen, NASA’s associate science administrator, who opened a news conference Wednesday highlighting the rover’s early progress. the first few months in his new home. “Perseverance is a step in a long legacy of carefully planned exploration of Mars that connects robotic and human exploration for the time to come.”
At the press briefing, the scientists presented what Perseverance has done on its journey so far. “The challenge is to figure out exactly where we want to go and how we’re going to fit everything into our schedule,” said Vivian Sun, a systems engineer at NASA’s jet propulsion lab. Sun said they decided to bypass the Perseverans about 3,000 feet south of his landing site to retrieve their first rock samples, which will be stored in the rover’s belly and later stored on the planet’s surface for a future return mission to transport them to Earth.