PBS America

Every day, hundreds of asteroids fall towards Earth. Small asteroids cause no harm, but large asteroids can have major consequences. There is no doubt that a killer asteroid will one day cross paths with the Earth… and that we will need to be ready to act. Knowing this threat is coming, the world's space agencies have set up specialist departments for detecting and exploring asteroids. For the first time in history, they are even planning on changing an asteroid’s orbit to protect the planet. Will we be able to avoid global catastrophe?

Her 60 years on the throne make her the second longest-serving sovereign in history, and in 2012 all eyes are on Queen Elizabeth II as Britain marks her Diamond Jubilee. In this fascinating series, veteran newsman Sir Trevor McDonald looks not only at the traditions and institutions surrounding the monarchy, but at the fabric of British life and history. From Changing the Guard at Buckingham Palace to the collection of Historic Royal Palaces; from a privileged glimpse at the making of a royal portrait to 600 years of counting royal swans on the River Thames; from a potential change to the rules of succession to the pomp and circumstance of a state visit, this is truly a showcase for a queen and her country.

They operate out of hiding and lurk in the depths of the oceans: submarines. When the 'submersibles' were first used over 100 years ago, hardly anyone believed in their usefulness. That changed during the First World War. For the first time, submarines operated militarily in larger numbers, and what were reconnaissance vessels quickly became hunters that sank enemy ships. The new weapon became a symbol of treachery, and submariners glorified as heroes by propaganda.

On the Battlefields of the World Wars: Since its invention at the start of the 20th century, the tank has served as a symbol of political power as well as military strength. These huge vehicles have long since found their way into global culture - whether as a monument, in films or on billboards. Tanks have made history and have themselves become part of the story.