英语听力：自然百科 探索世界奥秘之Life On Mars(火星生命)Unit12（在线收听）

But there was something even better. Odyssey may not just have found ice. There may also be liquid water, and that means, there could be living creatures there too.

Right now, there might be liquid water on Mars. It's not gonna be on the surface. But if we go down deep enough, it's almost certain we'll find liquid water at some point beneath the ice.

It's all down to the interior of the planet. Scientists believe that Mars' heart may be a great core of molten rock and metal. At the very center, it could reach temperatures of almost 2,000 degrees centigrade. This heat is spread outwards, so that despite the very cold surface of Mars, just tens of meters down, it may be warm enough to melt ice.

What Odyssey is seeing really is maybe just the tip of the iceberg, there could be, underneath that layer of ice that it could detect, a literal frozen ocean of water beneath that. Surprisingly, there could be life today on Mars beneath the ice in the liquid water, so the Odyssey results are also telling us that we ought to reconsider the possibility of life on Mars today, search for it more vigorously than we might have.

Odyssey's discoveries mean that there is now a genuine possibility that there is life on Mars. And if so, then we’ll soon have to start reconsidering our place in the universe. Odyssey's discoveries are so sensational that scientists are beginning to speculate: What strange creatures might be there waiting for us? What might an alien look like? Would they, for instance, be based on the same biological principles as we are?

When we look at life on Earth we see that all life on Earth uses the same chemistry, the same genetic code, the same hardware, the same software. It's really interesting to wonder if life on Mars, if it started independently, would it use the same code, the same chemicals?

On Earth, everything is based on DNA, but could it be that life on Mars is completely different, that there is an utterly alien way of doing genetics.

genetic code: The sequence of nucleotides in DNA or RNA that determines the specific amino acid sequence in the synthesis of proteins. It is the biochemical basis of heredity and nearly universal in all organisms