By 1983 a full-size prototype was completed

By 1983, a full-size prototype was completed.A spacecraft pulled by a solar sail - a large metal sheet, microns thick, that converts the momentum of sunlight into thrust - would be a very useful space vehicle. A sail of four square kilometres deployed from the Space Shuttle in Earth orbit could take a cargo-bay of payload to Mars before returning to Earth for more. An ordinary rocket motor would get the equipment there sooner, but would need up to three times as much fuel. It would also have to be lifted out of the Earth's "gravity well".A "sunjammer" solar sail vehicle could carry any amount of cargo; the only difference would be to the journey time. Permanent bases on other planets such as Mars would be delighted to receive such provisions. Sunjammers could therefore form a bridgehead and lifeline for such colonists.The Voyager 2 spaceprobe, now heading out of our solar system, will take some 80,000 years to travel the 4.3 light years (about 25 million million miles) to the nearest star - though it is not heading in the right direction.

A conventional solar sail could perhaps reduce this to about 15,000 years because it would keep accelerating while the sun was behind it. In interstellar space, there would be nothing to slow it down. That time seems an eternity when compared with an individual's lifespan, but some scientists have suggested that we could speed sunjammers up by firing lasers or microwave beams at them.Studies indicate that a solar sail 3.6 kilometres in diameter, trailing a one-tonne probe, could be powered by a 65 billion-watt laser fired from Earth orbit. Such energies are far higher than any yet obtained, but could conceivably be developed during the next century. Although the laser light would be a tight beam, it would tend to spread out over vast distances of space.

For this reason, a large Fresnel lens 1,000 kilometres wide, located at a stationary point between Saturn and Uranus, would be used to focus the laser beam on the receding probe. Three years of such acceleration would give it a velocity 10 per cent that of light, meaning that it would reach the nearest star system - the Alpha Centauri group - in about 40 years.Such ideas, although fascinating, are still deep in the realm of speculation. Other propulsion technologies may be better at propelling the first exploration trips to the stars, but it is not too fanciful to think of future space mariners plying the trade routes between the planets on sails of gossamer that ride the sunlight.Surprisingly, perhaps, Tennyson saw it - or something like it - in the last century: For I dip't into the future/ far as human eye could see./ Saw the vision of the world,/ and all the wonder that would be,/ Saw the heavens fill with commerce,/ argosies of magic sails,/ Pilots of the purple twilight,/ dropping down with costly bales.The writer is the BBC's science correspondent.. Catherine `She said well it's your body, don't blame me if it goes septic.

I got it done and showed her and she went, "Ooh, how could you?" ' Last summer I saw this lady on the beach with a sarong on and she'd had her navel pierced and I thought it looked really nice. I was in my science class with a group of friends, and one of them said to me that she was going to have her belly button pierced and she was really nervous about it. I'm one of these people who likes to prove that they're not nervous, and I'm quite outgoing, so I said I'll come along with you. My friend had it done, and I went home and asked my mum if I could get mine done First she said definitely not. Every time my friends came round she said: "Tell not to get her belly button pierced, because she'll regret it when she's older." Then I persuaded her. She said well it's your own body, don't blame me if it goes all septic. I went and got it done and showed my mum, and she went, "Ooh, how could you?" She didn't ground me, she just said, "Take care of it, but I don't agree with it and don't show it to me."It took about five minutes It didn't hurt because he numbed it up first with ice.

I said can I watch how you do it, but he wouldn't let me in case I fell off the stool. The bloke who did it had his tongue pierced, an eyebrow pierced, and he had a big feather going through his ear.My friend's bled a lot, but mine didn't. I had to clean it night and day and every time I had a bath I put antiseptic cream on it. My friend's went septic because she didn't clean it, and she had to have it removed - the skin grew through it.I asked my mum, a while back, if I could have a tattoo, and she didn't like the idea at all.