What's more, Pratt said his map showed that the feature is circular, which is characteristic of impact craters.

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The Shoemakers also travelled each year to the well-preserved impact craters in Australia.

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Shoemaker was studying asteroid impact craters in Australia and once said he would like to take a geologist's hammer to Eros.

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For the second, NEAR (Near Earth Asteroid Rendezvous) Shoemaker trained its lens on the saddle, a part of Eros that exhibits few impact craters.

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Impact craters surrounding the cap appear to be filled with ice and dust that was either deposited by wind or condensation, or perhaps further remains from an earlier larger ice cap.

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"Impact craters like this give us clues into how the Earth's crust is recycled and the speed of erosion, and may be implicated in episodes of widespread extinction of animals in the geological past, " Pratt said.

MSN: Massive meteorite crater found in Canadian Arctic

They show distinctive patterns of impact craters.

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Dr Amy Mainzer, principal investigator on the Neowise (Near-Earth Wise observations) project at the Jet Propulsion Lab (JPL) in California, said that "estimating the ages and origins of the asteroids should help us to correlate events on Earth and impact craters on the Moon with what is going on in the Solar System".

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Ebb and Flow broke into smithereens upon impact and pinpointing the small craters they carved was difficult, said Arizona State University researcher Mark Robinson, who operates the orbiter's camera.

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The team also found phyllosilicate deposits in thousands of places in and around craters, including the pointed peaks located at the centres of some impact depressions.

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