Life's ups and downs

摘要

If you're holding out hope for life on Mars, there's some good news and some bad news. A study of indigenous rocks here on Earth suggests that microbes would have a plentiful supply of energy on the Red Planet. But a report on tantalising traces of Martian plant life has bitten the dust. The hope for the presence of life on Mars lies below the surface, where many scientists believe there is still water in liquid form. On Earth, some microbes that live deep within rocks get their energy from hydrogen, which can be produced when water reacts with iron in the rocks.