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Mercury's core makes up about 60% of the planet by mass. It's about twice as big as earth. Why would it have such a huge core for such a small planet? Some people think there is a huge impact. A kind of strip off a lot of the planet and now what we're seeing is just a remnant of a once-bigger planet.
Many questions about Mercury remain unanswered. Questions' a new mission will hopefully solve.
Five, four, three, main engines start, two, one and zero, and lift off, phone? Messenger on NASA's mission to Mercury.
NASA's messenger spacecraft will become the first probe to orbit Mercury.
Getting a spacecraft into the orbit around Mercury is difficult for two reasons, the sun and the sun. The sun as a source of heat and the sun as a source of gravity.
注：听力文本来源于普特
