Water ice in the Vastitas Borealis crater, Mars

How did life appear on Earth?

For life to appear on Earth, the presence of water was certainly necessary. Scientists are currently studying three possible sources of life:

-Deep-sea vents: In an environment where light and oxygen do not exist, methane is often a key element for life to form, such as in underwater hot springs in the oceans.

- Icy oceans: Simple life forms capable of photosynthesis could have evolved in the oceans, protected from the deadly effects of ultraviolet radiation by icy crusts in the colder regions.

- Space: Bacteria almost certainly travelled on comets and meteorites between planets, and thus could also have been brought to Earth in this way.

For more information on this Mars Express image, please click on the following link: Water Ice in the Vastitas Borealis Crater.