NASA’s Space Launch System (SLS) is the most powerful rocket ever built. This is the story of the incredible engineering that went into building it, told first-hand by NASA’s best rocket engineers. Building the rocket that will take us back to the Moon is no easy task, but the payoff will be phenomenal.

The episode, devoted to the planet Mars, begins with scientific and fictional speculation about the Red Planet during the late nineteenth and early twentieth centuries (H. G. Wells' The War of the Worlds, Edgar Rice Burroughs' science fiction books, and Percival Lowell's false vision of canals on Mars). It then moves to Robert Goddard's early experiments in rocket-building, inspired by reading science fiction, and the work by Mars probes, including the Viking, searching for life on Mars. The episode ends with the possibility of the terraforming and colonization of Mars and a Cosmos Update on the relevance of Mars' environment to Earth's and the possibility of a manned mission to Mars.

A look at the probes which explored our Solar System, laying the groundwork for a future spacecraft to search for life on a second Earth. That space craft must communicate, it must navigate, it must have power, it must have propulsion. We will have to give it all the intelligence necessary to make its own decisions. In 'The Explorers' the spacecraft Artemis initiates launch sequence and begins its 4.7 light year journey to Minerva B - an Earth-like exoplanet.

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.

'The Coldest War': With the polar ice caps shrinking due to global warming, new trade routes are being exposed, along with billions of dollars' worth of natural-resource reserves. The five nations bordering the Arctic are readying themselves to fight for it. The problem is that there's one non-NATO country that already considers itself rightful owner of the region: Russia. With Vladimir Putin's recent military annexation of Crimea, there's a definite possibility its aggressions will boil over, returning the international community to precarious Cold War footing. We will head north to witness NATO forces participating in the largest polar military exercise in history. 'Heroin Warfare': Since the U.S. occupation of Afghanistan, heroin production in the region has skyrocketed, making the country the number-one producer by a large margin. Though Iran, Afghanistan's neighbor, is an ultraconservative country, Afghan heroin flowing across the border has actually caused Iran to have the worst heroin use problem in the world. Suroosh Alvi gets a rare look inside Iran to meet the suffering heroin addicts, and see how the country is coping with the illegal drug trade.

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.