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Surface of Mercury – Image: NASA
According to the journal Nature Geoscience on March 16th, a research team led by experts Paul K. Byrne and Christian Klimczak from the Carnegie Institution in Washington analyzed images and terrain data captured by the Messenger spacecraft.
They identified that Mercury’s radius has contracted by 7 kilometers over the past 4 billion years. Experts explain that the planet closest to the Sun is shrinking due to the cooling of its rock and metal core. In fact, scientists first observed Mercury shrinking when the Mariner 10 spacecraft flew past it in the mid-1970s.
However, the Mariner 10 spacecraft could only capture images of 45% of Mercury’s surface during its missions in 1974 and 1975. At that time, scientists estimated that Mercury’s diameter had shrunk by 1-3 kilometers. The Messenger spacecraft, launched in 2004 and entered Mercury’s orbit in 2011, captured more detailed images.
“With the Messenger spacecraft, we obtained high-resolution images of the entire surface of Mercury, which the Mariner 10 spacecraft couldn’t capture in the 1970s,” said expert Steven Hauck from Case Western Reserve University, one of the researchers involved.
With a diameter of about 4,880 kilometers, Mercury has a thin layer of rocky surface. Its core is metallic. Experts note that a part of Mercury’s metallic core is still in liquid form, but most of it has cooled and solidified.
In the near future, Europe and Japan will undertake a joint research project on Mercury, continuing the observational efforts initiated by the Messenger spacecraft.