An ambitious mission to uncover the past of the Solar System

It's the year 1799. Under the command of general Napoleon Bonaparte, the French have seized Egypt, then part of the Ottoman Empire. Near the coastal city of Rosetta, French soldiers unearth a stele finely covered in ancient writings: hieroglyphic, demotic and classical Greek. After several years of patient work, Briton Thomas Young and Frenchman Jean-François Champollion finally unlock its secret. The language of the ancient Egyptians is no longer a mystery.

Today you can admire the Rosetta stone for free at the British Museum in London, if you manage to get past the wall of people frantically taking pictures as if they'd just dug it up themselves. Or you can just look at the picture below.

©Matija Podhraški

That's indeed a fascinating story, but wasn't this blog about space and rockets and all that?

Of course. Please bear with me.

Languages evolve constantly, new ones are born and old ones wither and die, or change beyond recognition. It is hard to put back in place the pieces of this complicated story, unless... well, unless you find something very ancient that hasn't undergone all these changes.

Do you know what else has changed beyond recognition? Our Solar System did, since it was formed some four and a half billion years ago. Luckily for us, it is full of Rosetta stones that have not changed since those remote times. They are called comets and asteroids. We only have to get out there and grab one, and we may hope to discover a great deal about the history of our home in the Universe.

That's exactly the purpose of the European Rosetta mission, possibly the most ambitious mission ever set up by ESA. The space probe, which you can see in the model below, will get close to a comet and start orbiting it. Scientists on Earth will identify a suitable landing place, after which Rosetta will release a lander called Philae (still something Egyptian, if you must know). Philae will fire off two harpoons to anchor itself to the comet, after which it will perform a wealth of scientific experiments for about one year. A 3D model of the probe is shown below.

©n/a

As if that didn't sound complicated enough, wait to hear the following. The mission was initially scheduled for launch in January 2003 to reach a comet by 2011. About a month before launch, an Ariane 5 rocket blew up, and with it two telecommunication satellites worth 630 million euros.

Back at ESA headquarters they thought there was no rush to launch Rosetta after all.

The mission finally took off in February 2004, to meet comet 67P/Churyumov-Gerasimenko (I did not choose the name) in November 2014.

A trip lasting more than ten years. By that time most of us will have change their car once, their computer three times and their mobile phone too many times to keep count of. But Rosetta will still be the same, and everything on board will have to work as planned.

But why ten years? Why not choose a closer comet? Well, first of all a comet too close to the Sun would not be a safe environment for a lander (just read what happened to the Giotto probe when it flew by the Halley comet). Second, you can't just send Rosetta straight to its comet. This would be too much even for the most powerful rocket. Instead the probe is following a complicated spiralling trajectory, with one close encounter with Mars and three with Earth, meanwhile also paying a visit to a couple of asteroids. The reason is that, by flying close to a planet, a space probe can get a friendly "gravitational kick" and increase its speed for free. If I tried to explain this effect in detail I would probably lose the few readers I've managed to collect, so please just trust me.

In 2014 we will have the Winter Olympics in Sochi and the FIFA World Cup in Brazil. One hundred years after the First World War broke off, most EU member states in Eastern Europe will have adopted the euro as their currency. It will also be two hundred years since Thomas Young finished translating the demotic text on the Rosetta stone. On a faraway lump of dirty ice, a tiny robot will have just begun its quest to uncover a far more distant past.