Don: Hey, Yaël, Have you heard? We've discovered two new oceans?

嘿，Yaël，你聽說了嗎？我們已經(jīng)發(fā)現(xiàn)了兩塊新大洋。

Yaël: Where?

在哪啊？

D: On Mars. Well, they aren't there any longer, but they were there a few billion years ago.

在火星上。雖然現(xiàn)在不在那兒了，但幾十億年前一直都在。

Y: I thought scientists weren't sure if Mars had oceans or not.

我想科學家們還是不確定火星上到底有沒有海洋。

D: They weren't. The Mars Opportunity Rover found sulfates and other salts in the soil that were left behind when standing water evaporated. It also discovered cross-bedding in the soil which was created by water ripples, and tiny mineral deposits called blueberries that only appear if water is present. The northern lowlands of Mars looked like there might have been an ocean there, but there wasn't definite proof.

恩，不確定。機遇號火星探測器在土壤中發(fā)現(xiàn)了水分長期揮發(fā)后所留下的硫酸鹽和其它的鹽類。同時還在土壤中發(fā)現(xiàn)了水波所形成的交錯層，以及稱之為藍莓的小型礦床，而這種礦床只有在存在水的地方才產(chǎn)生。火星的北部低地看起來像是曾經(jīng)有過一片海洋，但還沒有發(fā)現(xiàn)確鑿的證據(jù)。

Y: So, what has changed their minds?

那又是什么讓科學家們改變了想法呢？

D: Gamma Ray evidence.

是伽馬射線。

Y: That sounds exciting.

聽起來真令人興奮啊。

D: It is. The Mars Odyssey spacecraft had a gamma-ray spectrometer onboard that could detect elements buried as much as a third of a meter, or thirteen inches, below the soil. Scientists used the spectrometer to measure the amount of potassium, thorium, and iron above and below what they thought to be the shoreline of ancient oceans. They expected to see low concentrations above the shoreline and larger concentrations below. That would indicate that the elements had been leached out of the soil by the water.

是啊。奧德賽號火星探測器有一個γ射線能譜儀主板，它可以檢測到埋藏于地底三分之一或地下13英寸的元素。科學家們利用光譜儀在所推斷的遠古海洋海岸線附近測量鉀、釷、鐵的含量。科學家們預(yù)測海岸線上的元素濃度較低，而海岸線以下的濃度較高。這將證明那些元素是通過水過濾到土壤中的。

Y: So, what did they find?

那么他們究竟發(fā)現(xiàn)了什么呢？

D: They found the shorelines of a younger ocean about ten times the size of the Mediterranean Sea, and an older ocean twice that size.

他們發(fā)現(xiàn)了一個較新，海岸線大約是地中海的10倍的海洋痕跡，和一個年代比較久遠相當于地中海海岸線兩倍的海洋痕跡。

Y: It's too bad those oceans still aren't there.

這些海洋已經(jīng)不在那兒真是太糟糕了。

D: Yeah. It sure would be a great spot for a cruise.

對啊，如果它們還在那兒，那將是個很適合巡航的地兒。