The European Space Agency's satellite Mars Express has identified what we think is a subterranean lake of liquid near the south pole of the red planet. The question of water on Mars has been around for years, and we've known about water ice, and there's been the possibility of seasonal flowing water on Mars for a while. But if this result is right, this is the first case of a substantial stable body of liquid water on Mars. Adam Rutherford talks to Roberto Orosei of the Radio Astronomy Institute in Bologna whose team made the discovery. Where should scientists be directing their efforts next in the light of this new finding? We hear from NASA's Chief Scientist Jim Green.

We've been growing embryonic cells in petri dishes for a few years now, to try to fill in the gaps in our understanding of early development, but the tissue that grows never really resembles an actual embryo. Magdalena Zernicka Goetz is a developmental biologist from Cambridge University and in a paper out this week has leapt over this hurdle in developmental biology using three types of stem cell, which - unlike previous efforts - push a ball of cells to becoming an embryo, which could help us understand why pregnancy can fail.

The Earth Biogenome Project aims to sequence the DNA of all the planet's eukaryotes, some 1.5 million known species including all known plants, animals and single-celled organisms. The project will take 10 years to complete and cost an estimated $4.7 billion. Harris Lewin from UC Davis is spearheading this scheme. How will he meet his ambition to curate all the DNA of life on Earth?

For the first time, scientists have assessed how much of the seas are untouched by the impact of human activity. They're referred to as Marine Wilderness, and qualify as such by being relatively untouched by things like fishing, pollution or agricultural run-off. According to the survey, published today, only 13% of the world's oceans remain as wilderness. James Watson from the University of Queensland discusss the action that needs to be taken if these precious ecological areas are to survive.

Producer : Adrian Washbourne.