Exactly ten years ago today, a signal from the Galileo spacecraft caused a bit of a stir. After almost a decade in space, and having sling shot itself around Venus to pick up speed, and dived through the atmosphere of Jupiter a couple of times, the automated probe's message was even more impressive: Europa has water.

Europa, one of Jupiter's many satellites, is slightly smaller than our moon, but a lot more interesting (geologically speaking, at least.)

Imagine a scotch egg. Those breadcrumbs are boulders and mountains of solid oxygen ice. Under that is a crust of more solid ice, at least ten miles thick. That can be the meat.

Now, at the centre of this planet is the yolk. In our case this represents an iron core. And it is in turn surrounded by the white of the egg, which is hard, solid rock.

So what's missing? Well, just as in a scotch egg, there's a gap between the egg and the meat, on Europa there's a gap between the rock and the ice. And what's getting NASA excited is that this area, the no-man's-land between a rock and a hard place, could well contain an unbroken layer of water fifty miles deep.

Let's imagine that they're right. The water is kept from freezing due to tidal forces exerted on it by the weight of Jupiter. Europa, (like most celestial bodies) isn't entirely round, and it generally shows only one side to the planet below (Just like with our own moon – the heaviest side faces earth, which is why we never get to see the other side). But there are other orbiters in Europa's neck of the woods, Other push-pull forces which are dragging at the moon for attention.

This is causing the solid core to rattle – albeit very slightly- inside its casing. The result is like one of those slush-puppy machines you might see at a bowling alley cafeteria : The water is never allowed to solidify because it's kept constantly on the move.

As you can imagine, Europa is high on the list of places we plan to visit. It makes sense. Out of everywhere we've looked in the neighbourhood so far, this looks like the only place we're likely to find the one thing we truly can't live without – water.

There's no shortage of speculation about what might be there. If the geeks are right, it's a salt water ocean, rich in minerals and nutrients. Drinkable, if you like sulphuric acid with your Martini.. I'm sure by now you've made the same connection that they have. Oxygen plus water equals... Life?

Just think about it for a moment. A never ending ocean, deep beneath ten miles of solid ice, fifty miles deep and always as dark as a tomb. It's not a fantasy place, or some made up concept. It's there, right now, whether you can see it or not. Doesn't it make you wonder?

Good. Here's the plan: It's March 2nd now. On March 29th, Sunday Journal will feature a short story about the exploration of Europa. And I would like to invite you to get involved. You know you've always thought you could write a pretty good story, of only you had an idea what to write about? Well, in a maximum of 2,500 words, write us a story based on the exploration of Europa.

Or you could paint a picture. If you like. Email your contributions to me at ArkSanctum by 28th (see the contacts section) and I'll be sure to post them for you. No prizes, no publishing deals. Just a great opportunity to share in a bit of fun.

This competition is open to regular ArkSanctum members but also to casual and one-off visitors. Just have a go and see what you can do. Even if it's just a hundred words. Go on. You know you want to...