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Asteroid Vesta Exceeds Expectations
by Richard A. Kerr 胡德良 譯
| The 529-kilometer-diameter asteroid Vesta is revealing even more geologic diversity than scientists had expected. They knew that a collision with another asteroid had splashed off three kinds of rock that still land on Earth as meteorites. And Vesta's overall spectral color, as returned by NASA's orbiting Dawn spacecraft, matches that of these Vesta meteorites, Dawn team members reported today at a planetary science meeting in Nantes, France. But rather than a monotonously uniform surface homogenized by impact cratering over the eons, the first up-close look at the asteroid reveals a full palette of mineral "colors" (mapped here in false color reflecting the wide range of rock compositions). Researchers will now have to sort out how more than 4 billion years of impacts—including one at the south pole that nearly destroyed the asteroid—reshaped Vesta after it developed a crust, mantle, and core much like Earth's. |
直徑為529公里的小行星——灶神星正在顯示出更加豐富的地質(zhì)多樣性，這種多樣性是科學(xué)家們以前沒有料到的?？茖W(xué)家們知道，灶神星曾經(jīng)跟另外一顆小行星發(fā)生碰撞，撞飛的三種巖石目前仍然以隕石的形式降落在地球上。今天，在法國南特舉行的行星科學(xué)會(huì)議上，“黎明”號(hào)太空船研究小組報(bào)道：NASA的軌道衛(wèi)星“黎明”號(hào)太空船返回的資料表明，灶神星整體的光譜色跟這些灶神星隕石的光譜色相符。由于無數(shù)代的隕石碰撞，灶神星并沒有形成單調(diào)一致、質(zhì)地均勻的表面。近距離乍一看，這顆小行星顯示出一整套“礦物色”（圖中描繪的并不是灶神星的真顏色，而是反映出其巖石構(gòu)成的多樣性）?，F(xiàn)在，研究人員必須要解決這個(gè)問題：灶神星形成了在很大程度上類似于地球的地殼、地幔和地核之后，經(jīng)歷了40多億年的碰撞，包括那次差一點(diǎn)兒毀滅這顆小行星的南極碰撞……這些碰撞又是如何重新塑造灶神星的呢？ |
譯自：美國《科學(xué)》雜志網(wǎng)站（3 October 2011, 2:01 PM）
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