It was hoped that Comet ISON could be the brightest and most spectacular comet for a generation. After travelling towards the sun for ten thousand years, it appeared to have been disintegrated by the heat and tidal forces of the sun in early December 2013.But ISON's tail of vapourised gas and water, hundreds of millions of kilometres long, may give insights into some of the greatest mysteries of science. It could help explain the origins of the solar system, whether earth's water was delivered on comets and even whether we are alone in the universe.

In the 1950s up to 8,000 people died every year on the roads in this country - a truly horrific figure. Thankfully it has now fallen to around 2,000 a year - still a terrible toll, but a vast improvement, particularly given the increase in cars on the road. Dallas Campbell looks back over decades of Horizon and BBC archive to chart the key scientific breakthroughs that have transformed road safety and saved millions of lives. However, it hasn't all been about innovative engineering and groundbreaking medical discoveries - scientists have also had to act as campaigners, persuading car manufacturers to install their life saving devices and urging the public to use them. (BBC FOUR)

It's a macabre paradox, but almost every advance in aviation safety has been driven by a crash. After every crash, investigators determine its cause and scientists make every effort to ensure the same mistakes never happen again. Dallas Campbell delves into the Horizon archives to chart the deadly disasters that have helped make air travel today the safest it has ever been. (BBC FOUR)

Sex is a simple word for a very complex set of desires. It cuts to the core of our passions, our wants, our emotions. But when it goes wrong, it can be the most painful thing of all. Professor Alice Roberts looks through 45 years of Horizon archive to see how science came to understand sex, strived to solve our problems with it and even helped us to do it better. Can science save the day when sex goes wrong? (BBC FOUR)

Bill Turnbull investigates one of the biggest mysteries in the British countryside: what is killing our bees. It is a question that generates huge controversy. Changes in the weather, pesticides and even a deadly virus have all all been blamed. It is a question that Bill is all too familiar with as a beekeeper himself. He meets the scientists who are fitting minute radar transponders on to bees to try to find answers.

Liz Bonnin delves in to the world of invention, revealing the people and technologies set to transform all our lives. She examines the conditions that are promising to make the 21st century a golden age of innovation and meets some of the world's foremost visionaries, mavericks and dreamers. From the entrepreneurs that are driving a new space race, to the Nobel Prize wining scientist leading a nanotech revolution, this is a tour of the people and ideas delivering the world of tomorrow, today.

Transplant surgery has now reached incredible heights, from achieving full face transplants to growing organs in the lab. This Horizon Guide looks back at the extraordinary odds doctors and patients have had to overcome to achieve these amazing breakthroughs. What we now take for granted has been a hard won struggle, both for the patients who were willing to gamble their lives and the doctors who faced ethical and medical dilemmas in the name of progress. Michael Mosley looks through the Horizon archive, identifying the key turning points for transplant surgery to explore how far science can go in its bid to prolong life.

On a bright, cold morning on 15 February 2013, a meteorite ripped across the skies above the Ural mountains in Russia, disintegrating into three pieces and exploding with the force of 20 Hiroshimas. It was a stark reminder that the Earth's journey through space is fraught with danger. A day later, another much larger 143,000-tonne asteroid passed within just 17,000 miles of the Earth. Presented by Professor Iain Stewart, this film explores what meteorites and asteroids are, where they come from, the danger they pose and the role they have played in Earth's history.