Hurtling through space at 24,600mp/h (39589km/h), Comet 67P/Churyumov-Gerasimenko has been following a largely predictable orbit around the sun for the last 3.6 billion years.

At 10:30 GMT on 12 November 2014 however, a man-made landing module called Philae, weighing just 100kg, detached from the Rosetta space probe and began its seven-hour descent towards a soft landing on the surface of the comet – the substance of which was unknown.

Five hundred and ten million km away at the European Space Agency in Darmstadt, Germany, a loud celebratory cheer shot up around the control centre, where scientists had been waiting for this moment for over a decade.

For Monica Grady, Professor of Planetary and Space Science at the Open University – and around 2,000 of the world’s most accomplished space scientists like her – the successful landing of the Rosetta Mission was the culmination of a lifetime’s work.

Smaller than expected, Comet 67P/Churyumov-Gerasimenko was just 4.3 by 4.1km when the Philae landed, likening the Rosetta Mission to landing a pin head on a speeding bullet.

With at least 5,253 comets in our solar system, these ‘dirty snowballs’ are leftover clumps of ice and dust dating back billions of years to the early formation of planets and stars.

It’s thought that once a collision between a comet and the earth delivered the first water to our planet, a catalyst for life and the starting point for millennia of evolution on our planet.

Scientists have long believed that the study of comets holds the key to a better understanding of the origins of our solar system. Now we know it’s possible to land equipment on moving comets, we can start to learn more where life on earth came from.

For more from this series click on the links below:

Alex Honnold: Reaching the peak

Erica Kochi: Tech that saves lives

John Bramblitt: Emerging from darkness