To boldly go where no amateur has before

Once upon a time, science and exploration were the stuff of the obsessive amateur, tinkering in his private laboratory. The glory days of the Victorian gentleman genius messing around with dangerous chemicals - and occasionally discovering something earth-changing - may have long passed.

But now, two Danish engineers are trying to follow in their footsteps. In a disused submarine hangar in Copenhagen, Peter Madsen and Kristian von Bengtson of Copenhagen Suborbitals have been building a space rocket from cork and duct tape (and steel, polyurethane, liquid oxygen and various other, less DIY materials).

The cork will form the heat shield (wood is an excellent ablative material, and rumour has it that the Soviets used it on their early probes), and the pilot's space suit, they told the media this week, is made from "valves and pipes from the hardware shop".

They tested how their brave putative astronaut stood up to G-forces by sticking him on a local fairground ride. They hope that the eight-ton craft will carry a human being into space - the first amateur-built rocket to do so. A hundred years ago, all this wouldn't have seemed so strange. The first few centuries of scientific discovery were led not by corporations or even universities, but by enthusiastic amateurs in garden sheds and garages - or the period equivalent. Albert Einstein himself did his greatest work - the Special and General Theories of Relativity - while employed as a clerk in a Swiss patent office.

The Wright brothers ran a bicycle repair shop, and tested their early flying machines in a home-made wind tunnel, before clambering into their rickety wood-and-linen contraptions and flying them themselves. The Wrights' approach to personal safety was a signature of the amateur scientist. The early Swedish chemist Carl Scheele, the discoverer of no fewer than eight elements (barium, chlorine, fluorine, manganese, molybdenum, nitrogen, oxygen and tungsten), insisted on sampling a small amount of every substance he used in his laboratory. Unsurprisingly, he died in that laboratory, in 1786 at the age of 43. His British successor, Humphry Davy, was just as keen a self-experimenter, dosing himself on his newly discovered nitrous oxide (laughing gas) with the merry abandon of a Glastonbury festival-goer.

Most reckless of all, perhaps, were the outstandingly eccentric father-and-son duo of John Scott Haldane and JBS Haldane. In an attempt to understand the effect of toxic gases on miners, Haldane senior spent some time poisoning himself with carbon monoxide, taking blood samples as he did so, and coming within a few moments of certain death.

His son JBS, who later would be a key figure in blending the findings of Darwin and Mendel into the "modern synthesis" of evolutionary theory, put himself (and, on other occasions, his wife, a former Spanish prime minister, and various others) into a compression chamber. In a remarkable series of accidents, he ended up giving his wife a seizure and himself several crushed vertebrae, perforated his eardrums, made dental fillings explode, and after one experiment with oxygen deprivation was left "without feeling in his buttocks and lower spine for six years".

Yet when not attempting to kill themselves, their friends or relatives, the amateur scientists were making huge strides. The early years of weather records were largely kept by Victorian men with splendid sideburns, recording wind speed and air temperature and pressure, which led to the first meteorological predictions. The scientists weren't all gentlemen, either: in 1811, at the age of 12, Mary Anning discovered the first ichthyosaur fossil (a 200-million-year-old, 17ft-long dolphin-like marine lizard). Over the course of her 35-year fossil-hunting career, she would find the first plesiosaur and an early pterosaur, all in the cliffs between Charmouth and Lyme Regis, Dorset, on what is now known - thanks in large part to her - as the Jurassic Coast.

The greatest of them all was Charles Darwin. His degree was in divinity, but he was a naturalist through and through. Although he is (rightly) best known for his theory of evolution, based on observations built up on an epic five-year round-the-world voyage on HMS Beagle, he spent his later years studying earthworms in his back garden, which he wrote up in his unjustly forgotten work The Formation of Vegetable Mould through the Action of Worms.

Between the return of the Beagle and the publication of On the Origin of Species, he spent the better part of a decade exhaustively studying barnacles ("I hate a barnacle as no man ever did before," he once said). Not every amateur scientist was a great hero, of course. For every Einstein and Darwin there were hundreds of crackpots, such as Percival Lowell, who believed that Martians had built canals to channel water from Mars's icy poles to its equator (although, in his defence, he also funded an astronomical research establishment, the Lowell Observatory in Flagstaff, Arizona, which is still operating today).

"They laughed at Columbus, they laughed at Fulton, they laughed at the Wright brothers," as the astronomer Carl Sagan put it. "But they also laughed at Bozo the Clown." None the less, these men and women in their studies were the engine of science for a long time. This age of the amateur started coming to an end in the 20th century, partly because the process of scientific publication became more formalised, partly because university science departments became better-funded and more organised, and partly, of course, because most of the low-hanging fruit had been picked.

Gregor Mendel could reveal the interaction of genes by carefully breeding pea plants; now, cutting-edge research in genetics often requires X-ray crystallography, or computer sequencing. In the 18th century you could discover a new element by using school lab equipment: now, you'll need a particle accelerator. Even early quantum physicists could do much of their work with electric lamps and thought experiments - but to confirm the existence of the Higgs boson took a multi-billion-dollar international collaboration and the better part of 50 years.

You just can't, on the whole, shake up the scientific establishment from your bedroom in the way that you could a century ago: the edifice is more secure, founded on that much more data. The spirit of adventure of the early years has not died away completely, however. Homer Hickham, a retired Nasa engineer, got his early breakthrough by building rockets in his Virginian coal-mining home town with friends.

Elon Musk (Paypal and Tesla) and Craig Venter (genome sequencing) have turned business success into scientific and technological advances. In 1981, Barry Marshall, an Australian doctor, even followed in the Haldanes' self-experimenting footsteps, drinking a glassful of Helicobacter pylori bacteria to prove that they, rather than stress, were the cause of stomach ulcers. The Danish amateurs, building their rocket from sticky-back plastic and old Fairy Liquid bottles or whatever it is, are unlikely to make any great scientific breakthroughs - although simply by showing that space travel can be affordable and accessible, they may pave the way for others.

But mainly, they are heirs to this tradition - the tradition of exploration, of dedicated amateurs obsessed with doing something, whether to show it can be done, to understand the world, or just because it is there. The Wright brothers would have understood.