S1, E3: The Earth has become a dangerous place to live in the Universe. It's only a matter of time before a cosmic force will annihilate the planet. At this very moment, NASA's top brass and other scientists are arming themselves with the latest technology to pre-empt an apocalyptic attack. And the enemy won't be terrorists launching nuclear weapons, but something possibly more deadly. This UNIVERSE episode - End of the Earth will investigate the bizarre, unexplained and terrifying End of Earth scenarios. Scientists from around the world race against the clock to develop technology to detect and defend our planet from apocalyptic demons. The prime suspects: asteroids, comets, gamma ray bursts, the sun and the Big Rip - a mysterious phenomenon called "dark energy" may eventually rip apart everything in the Universe.