Tue, Jun 03, 2008 - Page 14 News List

Radar map peels back secrets of the Martian north pole 雷達影像為火星北極揭密

This image provided by NASA shows a view of the north polar ice cap on Mars taken by NASA's Mars Reconnaissance Orbiter.


A radar map of the Martian north pole reveals a four-layer ice structure laid down over a period of five million years. The ice structure is on top of sedimentary rocks hundreds of kilometers thick, scientists said earlier this month in a report.

The data was provided by NASA’s Mars Reconnaissance Orbiter. It provides ground-breaking insight into the formation of the Martian ice cap and the “thermal history” of the red planet, said Roger Phillips of Southwest Research Institute in Boulder, Colorado, US.

Researchers found that the polar cap is formed by up to four layers of ice rich in sand and dust, separated by clearer sheets of ice. They believe the structure of the polar cap is the result of variations in Mars’ orbit over the years. One Martian year equals 1.88 Earth years.

The ice layers were accumulated over a period of about five million Earth years, said the scientists in a paper published in Science.

The radar images also show that the underlying sedimentary rocks have not been deformed by the enormous weight of the ice cap, suggesting that the Martian crust in the area is more than 300km thick.

The radar mapping of the polar cap also allows scientists to track the movement of dust over the Martian landscape over the years, researchers said.

The Martian north pole is part of a vast sedimentary plain built up over more than three billion years from ice erosion deposits, dust, volcanic lava and other sundry materials.






Caleb: What’s troubling you?

Elijah: Last night I went home smelling like perfume, and today my wife found a receipt for flowers. I’m really on thin ice.

Caleb: Well it sounds like you deserve to get into trouble.

Elijah: But I went to a perfume store to get my wife a present to celebrate our upcoming anniversary, and I got the flowers for my secretary for Secretary’s Day.

Caleb: That’s tough luck.






on thin ice 處境危險

To be on thin ice is to be in an uncertain state that could end up bringing trouble. For example, “Arianna is on thin ice with Mom because of her bad report card.”

「on thin ice」的意思就是處在一個可能會惹上麻煩的不確定狀況,例如:「雅莉安娜因為成績不理想,所以怕老媽會不高興」。




三十多億年來,冰蝕沉積物、 塵土、火山熔岩和其他各式各樣的物質,在火星上沉積成一片遼闊的平原,而火星北極就是其中一部分。


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