Looking at the way Mercury is spinning, NASA's planetary scientists have managed to deduce its internal composition. Researchers at NASA's Goddard Space Flight Center in Greenbelt, Maryland, have found evidence that Mercury's inner core is solid and almost the same size as the inner core of the Earth.
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"The interior of Mercury is still active, because of the molten nucleus that powers the weak magnetic field of the planet, compared to that of the Earth," said Antonio Genova, an assistant professor at the University. Sapienza of Rome, who led the research at Goddard of NASA.
"The interior of Mercury has cooled faster than that of our planet, Mercury could help us predict how the earth's magnetic field will change as the nucleus cools."
To explore the core of Mercury, the team used several observations from the MESSENGER mission (Mercury Surface, Space Environment, GEochemistry and Telemetry) on the spin and gravity of the planet. The MESSENGER spacecraft spent four years observing Mercury.
Scientists have been able to deduce that Mercury was turning much slower than the Earth. His days are about 58 Earth days.
The researchers used tiny variations in the way Mercury turns to reveal clues about its internal structure. However, more data was needed to determine the inner core of the planet. It is here that gravity came into play.
"Gravity is a powerful tool for looking deep inside a planet as it depends on the density structure of the planet," said Sander Goossens, a Goddard researcher who collaborated on this study with Genova.
As MESSENGER approached the surface of Mercury, scientists were able to extrapolate the accelerating acceleration of the spacecraft under the influence of planet gravity. The researchers then put all this data into a sophisticated computer program.
The results have detailed the interior composition of Mercury. The program showed that mercury had to have a large and solid central core of about 2,000 kilometers.
"We had to gather information from many fields: geodesy, geochemistry, orbital mechanics and gravity to determine the internal structure of Mercury," said Erwan Mazarico, a planetary scientist at Goddard.
The researchers hope to find even more discoveries on Mercury in the MESSENGER archive. "Every new information about our solar system helps us understand the larger universe," said Genova.
The study is published in Letters of geophysical research.