Castaway with no soap and a flatulent boffin

They can split atoms and clone sheep, but maroon scientists on a desolate island minus their gadgetry and can they conjure up a bar of soap? The BBC sent the Open University's Mike Bullivant and four others to find out.

Imagine waking up on a Mediterranean island. It is the height of summer and you have nothing else to do but spend the day with jaw-droppingly attractive Top Gear presenter Kate Humble. What is more, there is no way off the island for three weeks. You are stuck there. This is not some sad male fantasy - it actually happened to me last summer. I still pinch myself when I think about it.

Admittedly I had to share Kate's company with four other scientists, but so what? We were filming a new TV series to be broadcast later this month. The four parter - called Rough Science - finds the six of us marooned on the tiny island of Capraia in the Tuscan archipelago, with little more than our scientific wits, a few low-tech tools and the island's natural resources. Our resourcefulness was tested to the limit as Kate confronted us with a number of seemingly simple, yet teasingly difficult science-based challenges.

From the outset, Rough Science was never meant to be a survival series, nor is it entirely a docu-soap. Its aim is to explain the science behind some of the everyday things that we take for granted: soap, electricity, medicines and colour, to name just a few. What makes the series different is that the viewers are shown the science as it happens, and when things go wrong (as they frequently did) no attempt is made to hide the fact. This, after all, is the way science progresses. The scientific process is more about failure than success, as any practising scientist will tell you. Rough Science may also serve to shatter a few other popular misconceptions about science, in that it actually shows scientists enjoying what they are doing.

So, who were these intrepid scientists prepared to sell their self-respect and make idiots of themselves on prime-time television?

The Rough Science team comprised physicist Jonathan Hare from Sussex University, Mike Leahy, a molecular biologist from Oxford, ethno-botanist and freelance writer Anna Lewington, marine biologist Vanessa Griffiths from the Field Studies Council, and me, a chemist from the Open University. We were the survivors of an audition process that had taken the BBC production team months to complete. I guess they were looking for individuals with a good knowledge of science, an ability to communicate that knowledge with enthusiasm, a sense of fun and, above all, little sense of shame.

Our home for the three weeks' filming was to be Capraia's derelict prison complex. The first challenge Kate threw at us on our arrival was to work out where on earth we were - the production team had made sure our destination was kept secret.

On arrival, Jonathan and Mike L had no problem working out the island's latitude, but calculating its longitude proved to be a little more demanding, particularly as we had all been deprived of our watches at the airport. This was not going to stop Jonathan though, as he set about improvising a radio from a broom handle, half a saucepan and other assorted bits of junk that littered the prison yard and outbuildings. Luckily for him, Kate had very thoughtfully brought with her an earpiece and a galena crystal (the only bit of "cheating" we were allowed over the entire three weeks).

While Mike L and Jonathan beavered away at the longitude problem, Anna set off to investigate the island's flora. Filmed at the height of summer, we desperately needed something to keep the island's midges at bay. She returned with armfuls of plant material, from which we ended up extracting not only an insect repellent (rosemary oil), but antiseptics, analgesics, hair restorers and, most important, something for Mike L's flatulence.

As will become apparent to viewers, interpersonal relationships were sometimes stretched to breaking point, but we could always rely on Anna's pharmaceutical remedies.

In the meantime, Vanessa and I explored Capraia's coastline to see what we could plunder from the sea. You would be amazed at the 101 things you can do with seaweed. Making photosensitive film for one, which is just as well, because this was the particular gauntlet that Kate threw down at my feet.

Seaweed is rich in iodine, and treated in the right way it is a useful source of iodide ions. Force these to react with metallic silver (a bracelet purloined from Vanessa) in a home-made electrolytic cell driven by a bank of seawater batteries, and, hey presto, you have photosensitive silver iodide. It sounds easy, but the process required three other ingredients - blood, sweat and tears.

Over the three weeks of filming, Kate would come up with ever more demanding challenges. Later programmes see Vanessa, Jonathan and Mike building two types of generator in a quest to produce electricity.

My greatest challenge proved to be the manufacture of soap (thank you, Kate). I knew that you needed an oil of some kind, and that this had to be treated with an alkaline chemical. The former presented no problem as Capraia was covered in olive trees. But the alkaline chemical? Well, our forebears would have soaked the ash from their wood fires in water to produce potassium hydroxide solution. So that is what we did.

It was this constant revisiting the past that excited me most about the project. Without access to the simple reagents that any laboratory chemist would take for granted, we were forced to turn to methods of making them that were used centuries ago. Did I succeed in making any soap? You will just have to tune in and find out.

Mike Bullivant is a chemistry course manager at the Open University. Rough Science starts its four-week BBC2 run at 7.30pm on Friday, May 26. A website (www.open2.net) will set viewers a different virtual challenge each week. For those who want to take this interest further, the OU's science faculty has produced three new short courses. Details from www.Open2.NET/science.