英语听力：自然百科 探索世界奥秘之Alien Neighbors (寻访外星人) Unit07（在线收听）

“And so with Magellan we’ve got the first chance, one of the first chances, ok, to really get a complete map and view of it.”

The Venusian landscape has a desert-like appearance, but it’s a good deal hotter than any desert on earth.

“On Venus it’s about 500 degrees centigrade, due to that green house effects. So it’s far too hot for life to exist. In fact we think that that green house has existed for a very, very long time, so that even if we could get samples back on Venus, we don’t think we’d find any fossil evidence of life. Here on earth, there was abundant water and that’s where life began.”

Temperatures and pressures on parts of our own ocean floor are similar to those on Venus, not especially hospitable, in fact, downright hostile. Yet even in these conditions where there is no oxygen, life flourishes around smoking, hydrothermal vents. All over the earth, there are amazing examples of life surviving even thriving in harsh environments. These hardy life forms on earth add power to the argument that life may once have existed, may still exist, in forbidding environments elsewhere in the solar system. The first humans to land on Mars may yet discover the imprint of life.

“We don’t know that life originated on earth. It could have come here from elsewhere in a meteorite or comet or something. Now from time to time, asteroids and comets hit Mars and splash Martian material around the solar system. And we know that some of this material comes to earth because there are about a dozen meteorites that have been identified that come from Mars. One of these meteorites could have brought life here to earth.”

This is no ordinary rock. It was found on earth but it came from Mars, one of at least a dozen alien rocks from the Red Planet. 13,000 years ago a rock fell to earth. In 1984, it was found in Antarctica, at a place called Alan Hills. For over a decade, this Mars meteorite stayed at NASA’s Johnson Space Center. It had been mistaken for a piece of the moon. But in 1996, NASA scientists took a second look. Inside the meteorite, there appeared to be microscopic fossils, possible signs of life. The meteorite made front-page news around the world. But the initial euphoria was replaced by doubt when the evidence proved to be inconclusive.

“The Alan Hills Meteorite is a very important find. It, the things that we do know for sure is that this meteorite is very old. It’s one of the oldest objects in the solar system. It had fractures that were filled with carbonates precipitated from environments, perhaps not unlike this one. I mean we think perhaps they were hydrothermal.”

Even if the Alan Hills Meteorite shows evidence of possible microscopic fossils, this is still not proof of life on Mars.

“So really, where we rest on the Alan Hills Meteorite is that it’s an important find but not indicative of biology.”

“What a time to be alive! In the last year we’ve discovered planets around nearby stars, and today….” NASA Administrator Dan Golden.

words in this passage:

abundant: more than enough 丰富的, 充裕的

downright: (especially of something bad) extremely or very great 完全地；彻头彻尾地

hydrothermal:热水的, 热液的

forbidding:unfriendly and likely to be unpleasant or harmful:可怕的, 令人难亲近的

meteorite : a piece of rock or other matter from space that has landed on Earth 陨星

asteroids: one of many rocky objects, varying in width from over 900 kilometres to less than one kilometre, which circle the sun　小行星

front-page : describes information that is so important that it deserves to be printed on the front page of a newspaper:重要的, 轰动的

euphoria: extreme happiness, sometimes more than is reasonable in a particular situation:兴高采烈

precipitate: If a liquid precipitates, substances in it become solid and separate from the liquid:沉淀；（空气中水汽）凝结