The attempt to send and land astronauts on Mars risks billions of dollars and the lives of those brave enough to attempt it. Is the possible benefit really worth the risk? And is it really achievable? Guiding us through this ethical and scientific minefield is Dr Kevin Fong. Kevin's diverse background in astrophysics, aeronautics and medicine makes him uniquely placed to understand the technical and human challenges of this perilous journey. He leads us through the journey to Mars stage by stage. For Kevin, not only is this the toughest journey we will ever attempt, it is one that he feels we ultimately must make if we are to survive as a species.

Across the universe, galaxies are going dark, and scientists don't know why the stars are losing their shine. Something is slowly drawing the curtains closed on the universe. Our milky way is under threat. Astronomers race against time to uncover the truth behind how galaxies are born and how they die before all of the lights go out.

Once they were dreaded and thought to be dragons eating the sun--but modern science has dispelled mythology and we now look forward to total Solar Eclipses as one of the most spectacular phenomena in the heavens. Explore the complex movements of Earth, Moon and Sun that produce these unusual events and hear details why we may be the only intelligent beings in the known Universe to witness eclipses like we see on Earth. Man-made eclipses also figure into the science in the form of instruments called "coronagraphs." They blot out the sun and reveal its corona, uncovering secrets which, while enlightening, also warn of a disaster that could make our advanced technology crash and burn. Finally, travel into deep space, where the tiny eclipses caused by planets circling distant stars is now beginning to reveal hundreds more stars where "exoplanets" exist... perhaps even those in habitable zones like the Earth.

From lush cloud forests to bare summits that take your breath away, the higher you climb the tougher life gets on a mountain. Human Planet explores the extraordinary ways in which people survive at extreme altitudes where nature becomes utterly unforgiving. In the Altai Mountains in Western Mongolia the vast open spaces make hunting for animals almost impossible, so the locals have forged an astonishing partnership with golden eagles which can do the hunting for them. On the precipitous cliffs of the Simien Mountains of Ethiopia we join a young boy locked in a dramatic battle with fearsome gelada monkeys which are hell-bent on raiding his family's meagre grain harvest. In the Himalayan state of Nepal - the roof of the world - we witness a rarely seen ceremony: a sky burial. In a land where there is little wood to burn for cremation, and where burying the dead is virtually impossible, the dead are fed to vultures in the ultimate reverence of nature.

The Milky Way, our galaxy, is a magnificent sight in the night sky, but we know surprisingly little about it for certain. What is its shape? How many stars does it actually contain? What lies at its centre? The Gaia space telescope will answer these questions, being armed with the most advanced camera to leave our planet, and it will allow us to see our galaxy as we've never seen it before. The Sky at Night visits the factory in Chelmsford that made the astonishing sensor at the heart of the mission.

Professor Brian Cox concludes his exploration of our place in the universe by asking what next for the ape that went to space. Our future is far from certain. In Florida, Brian joins the latest efforts to protect Earth from potential catastrophic events. He joins a team of Nasa astronauts who are training for a future mission to an asteroid - should we ever discover one coming our way - under 30 feet of water in a submerged laboratory that simulates space. It is just one example of how, for our long-term survival, space exploration may well be vital. It is a view shared by Apollo 16 astronaut Charlie Duke, who tells Brian what it was like to escape the confines of the planet. It is a dream that both Nasa and now commercial companies share as they race to get humans back into deep space.
But space travel, like every leap our civilisation has ever made, requires energy. Here too, scientists are hard at work attempting to safeguard our future. At the National Ignition Facility in California, Brian witnesses the world's most successful fusion experiment in action. He believes that if their mission succeeds, our civilisation will have unlocked a way to the stars that will not destroy the planet in the process. Brian concludes by returning to the top of the world in Svalbard, where he gains access to our civilisation's greatest treasure, locked away in a vault buried deep in the permafrost.