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Exteme Makeover Science Edition
Exteme Makeover Science Edition

Who's getting made over, I hear you ask. Well - you might have heard of him. Alvin. No, not one of the chipmunks but a submarine.

Alvin was the first Deep Submergence Vehicle (DSV). It is a tiny submarine designed to dive to incredible depths, over 2400 meters or 8000ft. This is not an easy job to ask any vehicle to do. At that depth the pressure of water trying to crush it is about 2.5Ktonnes per square metre. In many ways it is easier to keep people alive in space than at such depths.

DSV Alvin

How does Alvin survive such conditions?

On the surface Alvin looks like a rather squashed tin can with bits sticking out. These bits are really just the add ons that disguise the clever bit underneath. The part that really does the business is a 50mm thick sphere of pure titanium. It makes for uncomfortable living but a sphere is the best possible shape for withstanding pressure.

Whate makes the sphere so strong?

Liquids under pressure push equally in all directions. A sphere is the only shape that is really strong in all directions. Nature knows this and tries to make things that need to be strong in this way as close to spherical as possible within the limits of other design parameters. Even the human skull has a pretty spherical brain chamber!

Drawing of DSV Alvin

The really tricky part is keeping the sphere intact when it has holes in it. It's a bit pointless have strong structure if you can't get into it through a hatch or see out of it through windows. Alvin has a hatch 48 cm across and three small windows through which some of the world's great discoveries have been made.

Why would I have heard of Alvin?

Well, Alvin has many feathers in his bow, some of them being that Alvin was the first craft to see the 'black smokers' around hydrothermal vents. These are the outpourings of heat around underwater volcanoes. Everyone thought that these deep dark places would be deserts. But they were in fact absolutely teemed with life. Many kinds of which were completely new to science.

Alvin at Sea

It was also one of the first vehicles to map the wreck of the Titanic.

Alvin is in the process of a complete refit. It will soon be able to dive to more than 6.5 KM. At this depth it will be able to visit more than 98% of the ocean floor. At the moment it can only access about 68% of what's down there. More discoveries are sure to follow.

The Reveal

The new Alvin will be altogether better. Its new crew sphere will be bigger and have five portholes instead of three. It has already been cast out of 15.4 tonnes of pure titanium. It will be powered by new lithium ion batteries, like those used in mobile phones. These will allow it to stay down much longer. At the depths Alvin works it cannot be linked to the surface. You would need a cable 6.5 Km long! This means Alvin must fly free like a spacecraft. In fact many of the problems associated with deep sea exploration are similar to space exploration. You need to carry your own oxygen and power and are effectively beyond the range of rescue. Any serious failure runs the risk of proving fatal. Systems need to be engineered very carefully! You also have the same toileting problems. (Take a bottle and don't have a Balti the night before!)

Inside a Submarine

The new Alvin will represent the cutting edge in Earth exploration. Huge tracts of the ocean are as unexplored as the outer solar system. It will be years before we can say we have truly explored the surface of our home planet. Alvin will still be a big part of that quest.

Big Questions

How can we study the deepest parts of the ocean?

How can a submarine survive the huge pressures when it is diving miles deep?

Why explore so deep?