When mankind eventually leaves the cradle of Earth and ventures forth into the uncharted territories of the cosmos, where, and what form, will our new homes take?

It sounds like a Hollywood blockbuster: a deadly asteroid is on a collision course with Earth. But in reality, it's only a matter of time before a giant space rock threatens to wipe out civilization. An asteroid took out the dinosaurs sixty-five million years ago. Are we next? This episode analyzes the threat and explores the many ways--from a nuclear bomb to ingenious new technology--that experts are proposing to stop Armageddon

It was the defining moment of the 20th Century - the scientific, technological, military, and political gamble of the world's first atomic attack. This drama-documentary attempts to do what no other film has done before - to show what it is like to live through a nuclear explosion, millisecond by millisecond. Set in the three weeks from the first test explosion in New Mexico to the eventual dropping of the bomb, the action takes viewers into the room where the crucial political decisions are made; on board the Enola Gay on her fateful voyage; inside the bomb as it explodes; and on the streets of Hiroshima when disaster strikes. Parallel storylines interweave, unfolding the action from both US and Japanese perspectives, and revealing the tensions and conflicts in the actions and minds of people who were making history. Special effects recreate the reality of the mission - even going inside the workings of the bomb - and archive film replays the horrific aftermath.

During 1953-1958, as the Cold War intensifies, Korolev is asked to build a rocket capable of carrying a five-ton warhead to America - he designs and constructs the R-7 Semyorka, and is later allowed to use it to launch the first satellite, Sputnik 1. Meanwhile, von Braun struggles to persuade the US government to allow him to launch his own satellite - after Sputnik's launch and the failure of the US Navy to launch a Vanguard satellite, he is finally allowed to launch the first American satellite, Explorer 1.

During 1964-1969 both sides now plan to put a man on the Moon - while the Soviets struggle, the Americans pull ahead in the space race with Project Gemini, but then suffer a disaster with the Apollo 1 fire. The Soviet space programme suffers its own blows: Sergei Korolev dies when his heart fails during an operation, Soyuz 1 crashes and kills cosmonaut Vladimir Komarov, and their planned moon rocket, the N-1 rocket, fails to successfully launch. In America, von Braun has difficulties with the Saturn V, but they are overcome, and the rocket successfully launches the first manned lunar mission, Apollo 8, and the first manned lunar landing, Apollo 11.

In the third programme of the series, Aleks gives the lowdown on how, for better and for worse, commerce has colonized the web - and reveals how web users are paying for what appear to be 'free' sites and services in hidden ways. Joined by some of the most influential business leaders of today's web, including Eric Schmidt (CEO of Google), Chad Hurley (CEO of YouTube), Bill Gates, Martha Lane Fox and Reed Hastings (CEO of Netflix), Aleks traces how business, with varying degrees of success, has attempted to make money on the web. She tells the inside story of the gold rush years of the dotcom bubble and reveals how retailers such as Amazon learned the lessons. She also charts how, out of the ashes, Google forged the business model that has come to dominate today's web, offering a plethora of highly attractive, overtly free web services, including search, maps and video, that are in fact funded through a sophisticated and highly lucrative advertising system which trades on what we users look for. Aleks explores how web advertising is evolving further to become more targeted and relevant to individual consumers. Recommendation engines, pioneered by retailers such as Amazon, are also breaking down the barriers between commerce and consumer by marketing future purchases to us based on our previous choices. On the surface, the web appears to have brought about a revolution in convenience. But, as companies start to build up databases on our online habits and preferences, Aleks questions what this may mean for our notions of privacy and personal space in the 21st century