Day Two

We go off to the mine to try out what we have - the exposed light-sensitive diodes from the radio, the laser pointer and a multitude of different reflectors. It's deliciously, amazingly cool inside the mine. A blast of cold air comes racing at you just on opening the doors. It feels too good to be true in the heat of the desert! You can't believe it will continue to keep blowing.

It takes AGES, just ages, to work out and to film. We do find that smaller tubes make the tin foil vibrate more. That may be good - we may need to maximise the response. But maybe we just need to use bigger reflectors - casting a light beam over a distance is harder than I'd imagined. Using a wider light beam may be necessary just to be able to see the damn thing to be able to line it all up. At least we've learned something and Jonathan's detector worked.

I tried out different options outside the mine - a bit of mirror stuck on a rubber diaphragm (a bit of old car tyre) compared with a tube with tin foil stretched over it. Jonathan tweaked his diodes, I played with my reflectors, then we set it all up outside - and it all felt quite promising. It actually worked. Everyone was delighted.

The challenge now is to make it work over a distance of more than 15 metres. In fact, Kate now tells us we have to get a signal across the length of the mine. Hmmm! Thanks, Kate!