A meteorite, certifiably from Mars, carried the chemical signature of what could be the by-products of Martian metabolisms.

现已证实来自火星的一块陨石携带着一种化学物质，它们可能反映出火星上生命新陈代谢的某些特微。

That idea got a big boost last week with the discovery that some comets, at least, have the same chemical signature as the water found on Earth.

上周这一理论取得了重大进展，随着科学家发现至少部分彗星和地球上的水相同的化学特性。

Researchers studying rocks brought back by astronauts have found that the moon's scarce water has a different chemical signature than Earth water.

研究人员通过研究宇航员从月球上带回的岩石发现月球上那少得可怜的水其化学成分跟地球上的水不同的。