The researchers found that the core density is surprisingly low, only about 6 grams per cubic centimeter, which is far lower than their expectations for iron-rich centers. “Why the core is so light is still a mystery,” Stähler said. There must be lighter elements, although it is unclear what these elements are. He and his team eventually hope to detect P waves from earthquakes that pass through the earth directly from the InSight parking lot. Because they can penetrate the core-mantle boundary, they transmit information about the composition of the core to the lander’s receiver. But to do this, Stähler said, “Mars must cooperate and bring us this earthquake on the other side of the earth.”
In the Stähler team’s paper, they reported a core radius of 1,830 kilometers. Another team led by Amir Khan, a geophysicist at ETH Zurich, discovered that this size is so large that there is almost no room to accommodate the lower mantle similar to the Earth, which is a layer that acts as an endothermic blanket around the core. Floor. The mantle is divided into two parts, with a so-called transition zone in the middle; the upper and lower layers are composed of different minerals. “The Martian mantle is-I can say lightly-a slightly simpler version of the Earth’s mantle, in terms of mineralogy,” said Khan, the lead author of the paper describing the mantle.
Previous estimates of the core radius using geochemical and geophysical data implied the absence of the lower mantle, but scientists need InSight seismic readings to confirm this. Without this layer, the core of Mars may be easier to cool than the Earth. This is the key to understanding the evolution of this red planet, especially why it lost its magnetic field, which is a barrier to protect the atmosphere and potential life from the harsh solar wind. Generating a magnetic field requires a temperature gradient between the outer core and the inner core. The temperature gradient is high enough to generate a circulating current, which agitates the liquid in the earth’s core and generates a magnetic field. But the core cooled so fast that these convections disappeared.
Khan’s analysis also showed that Mars has a thick lithosphere, a hard and cold part of the mantle. This may be a clue as to why the red planet did not promote the plate tectonics of the Earth’s volcanic activity. “If you have a very thick lithosphere, it will be very difficult to break it down and create an identical plate structure on the earth,” Khan said. “Maybe Mars had it a long time ago, but it must be closed now.”
While InSight eavesdropped on the internal vibrations of Mars, Perseverance has been rolling on its dusty surface, looking for signs of ancient life in the rocks, looking for places to collect samples of the weathered layer, and learning about Jezero’s geological history. “Exploration is not a sprint, but a marathon,” said Thomas Zurbuchen, NASA’s deputy director of science, who emphasized the early progress of the rover at a press conference on Wednesday. The first few months In its new home. “Perseverance is a step in the long legacy of carefully planned Mars exploration, which connects future robotics and human exploration.”
Scientists at the press conference described Perseverance’s performance on road trips so far. Vivian Sun, a systems engineer at NASA’s Jet Propulsion Laboratory, said: “Our challenge is to figure out exactly where we want to go and how we will arrange everything in our schedule.” Sun stated that they decided to detour the Perseverance. About 3,000 feet south of the landing site to extract its first rock samples, these samples will be stored in the abdomen of the rover, and then cached on the surface of the earth for future return missions to transport them to the earth.