An American spacecraft is moving closer to a dwarf planet called Ceres. The American space agency's Dawn spacecraft is set to reach the planet-like object in March.
一艘美国飞船正在接近一颗名为谷神星（Ceres）的矮行星。美国航天局的曙光号飞船（Dawn spacecraft）将于三月份抵达这颗类行星。
Space agency scientists will then place Dawn in an orbit around the dwarf planet. Agency scientists want to know more about ice on Ceres. The spacecraft will gather clues about whether Ceres may have once had conditions to support life as we know it.
航天局科学家届时将让曙光号飞船环绕这颗矮行星的轨道飞行。该机构的科学家希望更多地了解谷神星上的冰壳。该飞船将收集线索，了解矮行星是否可能曾经拥有我们所知的支持生命存活的条件。
Dawn left Earth more than seven years ago on a trip to explore Ceres and another dwarf planet, called Vesta. Both dwarf planets are in the main belt of asteroids, a group of large objects, between the planets Mars and Jupiter.
曙光号飞船于七年多前离开地球，开始了一段探索谷神星和另一颗名为灶神星的矮行星的旅程。这两颗矮行星都位于火星和木星之间的小行星主带。
Marc Rayman is the chief engineer and director of the Dawn mission.
马克·雷曼（Marc Rayman）是这次曙光号行动的首席工程师和负责人。
"This is the first time in more than 57 years of space exploration that we have a spacecraft targeted to orbit any two extraterrestrial destinations."
他说，“这是57年多来的太空探索中首次有飞船以任意两颗外星球为目标进行围绕运行。”
Scientists call Vesta and Ceres "protoplanets." Mr. Rayman says they were in the process of becoming full-size planets when, in his words, "their growth was terminated."
科学家们称灶神星和谷神星为原行星。雷曼先生表示，在变成正常行星的过程中，它们的成长被终止。
Scientists believe Ceres is made of rock, and covered with ice.
科学家们认为谷神星由岩石组成，表面覆盖着冰壳。
The Dawn mission is based in Los Angeles, California. Scientists there send second-by-second commands to the spacecraft. They direct its every move, including telling it what pictures to take. Dawn will make a map of the dwarf planet. It will also try to discover how Ceres' surface has changed.
曙光号行动的总部设在加州的洛杉矶市。科学家在这里向该飞船逐秒发送信号。他们控制飞船的一举一动，包括告诉它拍摄什么样的照片。曙光号飞船将为这颗矮行星绘制地图。它还将试图找出谷神星表面如何变化。
Carol Raymond is the deputy principal investigator of the project.
卡罗尔·雷蒙德（Carol Raymond）是该项目的副首席研究员。
"One of the interests in bodies like Ceres and other icy bodies in the outer solar system is that when objects like that impacted the terrestrial planets, they brought a lot of water. So there's a very vigorous debate at the current time as to whether wet asteroids like Ceres -- and we know there are other wet asteroids in the outer edge of the main belt -- whether they were the dominant source of water in the Earth's ocean."
她说，“人们对谷神星和其它冰壳星球之类的外太阳系星球感兴趣的一点在于，当这类星球撞击类地行星时，它们会带来大量的水。所以目前争论很激烈的是，像谷神星这类含水分的小行星是否是地球海洋的主要水源。我们知道在小行星主带的外边缘还有其它含水的小行星。”
Carol Raymond says Dawn made an unexpected discovery while orbiting Vesta.
雷蒙德表示，曙光号飞船在环绕灶神星运行时取得了意想不到的发现。
"Instead of being bone dry, which we expected, there were patches on the surface of Vesta that showed significant amounts of water bound in the rocks and possibly even free water that could have flowed on the surface in the past."
她说，“灶神星并非如我们预期的完全干燥，它的表面有裂纹，这明显表明过去岩石中含有大量水，甚至可能有流水曾经在星球表面流动。”
She says that if Earth's water came from wet worlds like Vesta and Ceres, then life could have developed there, too.
她说如果地球上的水来自类似灶神星和谷神星的含水行星，那么生命也可能在那里孕育。
If Dawn finds that the environment of Ceres could have supported life, scientists may seek to explore the dwarf planet with other scientific instruments.
如果曙光号发现谷神星的环境原本适合生命生存，科学家可能会寻求使用其它科学仪器探索这一矮行星。
Dawn will gather information about Ceres until the middle of 2016. It will then continue to orbit the small planet.
曙光号飞船将会收集有关谷神星的信息，直到2016年中旬。然后它会继续环绕这颗小星球运行。
I'm Marsha James.
我是玛莎·詹姆斯（Marsha James）。(51VOA.COM对本文翻译保留全部权利，未经授权请勿转载，违者必究！)