Be Prepared!
BY ADRIAN BERRY
Posted: June 14, 2008

WHEN astronauts travel to Mars, there is an ominous possibility that they will all die during the voyage from poisoning by cosmic rays from distant parts of the Galaxy.
This could occur because the designers of their ship may have underestimated the difficulties of protecting its inmates from these energetic particles from far off in space that will crash into the hull at almost the speed of light and penetrate their bodies.

It has all happened before. The architects of ships have often made errors, and travellers have died from them. Time after time in the 19th century, mariners failed to reach the North Polar regions because their ships, although seemingly of brilliant design, were unsuited for the ferocious environments they would meet.

In 1844 the British Admiralty put Sir John Franklin in charge of three of the new propeller-driven steamships, believing that these at last gave them the means of breaking the ice to penetrate the North West Passage.

The propellers could be pulled clear of the ice if necessary, and – a then unheard-of luxury – a system of hot-water pipes warmed the cabins. But none of these preparations did any good. All three ships were crushed by the ice, and none of the officers or crew returned to civilisation.

Some thirty years later, another determined effort to get through the ice was made by the energetic owner of the New York Herald, James Gordon Bennett.

At the cost of the then huge sum of $100,000, he had a polar exploration ship, the Jeannette, built with extraordinary defences. Its bow was bolstered by 10 feet of solid oak and pine. Its sides were thickened by planking to a depth of more than 20 inches. And solid oak beams, 12 by 14 inches, were laid athwart-ships to withstand any conceivable pressure.

When the Jeannette cleared San Francisco bay on July 8, 1879, its crew was as optimistic as Sir John Franklin's men had been. But the splendid carpentry proved to be of no use. Soon after entering the ice, the bow buckled and the seams opened. The ship tilted crazily and had to be abandoned.

And these problems have never really been solved. Even with the current melting of ice, the best way to the North Pole is still either by flying or by submarine.

Like a trip into deep space, these were voyages that nobody knows in advance how to survive. 

A manned spaceship on its way to Mars obviously has to be covered with some substance that will repel cosmic rays. But what substance? There are several candidates.

The obvious one is lead. This heavy metal will absorb almost any radiation, but it is just too heavy. To coat the inhabited parts of a spaceship with lead would make the vessel so much harder to propel that it would make the voyage intolerably expensive.

Another solution is to cover the crew quarters with a layer of water, since water absorbs radiation. But water is difficult to control. Such a plan is complicated and could easily go wrong.

A more sure solution is a covering of some kind of plastic. Plastic is much lighter than metals such as aluminium, and the number of possible plastics, like the possible number of compounds of carbon, is immeasurably huge.

At all events, if a catastrophe is to be avoided, the problems of protecting the crew from radiation must be fundamental to the ship's design, not put on at the end as an afterthought. Unlike the polar mariners of two centuries ago, Mars voyagers must be truly prepared for danger.

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Visit Adrian Berry's website at www.adrianberry.net He is Consulting Editor (Science) of the Daily Telegraph.