As of 5 July 2016, the United States Strategic Command tracked a total of 17,852 artificial objects in orbit about the Earth, including 1,419 operational satellites. Take a look at the mounting threat of debris in Earth's atmosphere, the potential dangers of such 'junk' and what can possibly be done to avoid a crisis. The film is a visually explosive journey of discovery that weighs the solutions aimed at restoring our planet's orbits.

This series shines a spotlight on the influential builders, dreamers and believers whose feats transformed the United States, a nation decaying from the inside after the Civil War, into the greatest economic and technological superpower the world had ever seen. The Men Who Built America is the story of a nation at the crossroads and of the people who catapulted it to prosperity. In the first episode, Cornelius Vanderbilt grows from a steamboat entrepreneur to the head of a railroad empire, and gets into a heated rivalry with Jim Fisk and Jay Gould; the up and coming John D. Rockefeller founds Standard Oil. Many business owners lay their own rail lines which leads to the Panic of 1873. Later, Rockefeller starts to expand his wealth by diverting his business from the railroads to a new innovation, oil pipelines.

In the last episode, Iain discovers the remarkable impact of just one plant: grass. On the savannah of South Africa he sees how grass unleashed a firestorm to fight its greatest enemy, the forests. He shows how cutting your finger on a blade of grass shows us how it transformed life in the oceans. In Senegal, he meets the cleverest chimps in the world. And, in the ruins of the oldest temple on Earth, he tells the extraordinary story of how grass triggered human civilisation.

In the second episode, Professor Iain Stewart discovers how flowers have transformed our planet. He journeys to the remote islands of the South Pacific to track down the earliest flowers. In the deserts of Africa and rainforests of Vietnam, he sees how they brought brilliant colour to the most barren landscapes and sculpted the earth itself. And he learns how they drove the evolution of all animals - kick-starting our human story.

In this series Professor Iain Stewart tells a stunning new story about our planet. He reveals how the greatest changes to the Earth have been driven, above all, by plants. In this first episode Iain journeys from the spectacular caves of Vietnam to the remote deserts of Africa. He sees how plants first harnessed light from the sun and created our life-giving atmosphere. He uncovers the epic battle between the dinosaurs and the tallest trees on the planet. And, using remarkable imagery, he shows plants breathing - and for the first time talking to each other.

In the second episode, Andrew Carnegie builds an empire around steel, but finds himself struggling to save face after the ruthless tactics of his business partner, Henry Frick, result in both the Johnstown Flood as well as the bloody 1892 strike at the Homestead Steel Works.