Day Two

‘What is the recipe for gypsum?’

Kathy and I go into the mine to test out the mirrors and the receiver. We were told that there are more than 40 miles of mine tunnels in this area! As the door is opened to the shaft a very cool breeze blows out from the mountain side – it’s almost cold in there!

We play around with a small laser pointer and Kathy discovers that the fine spot of the beam is very good at showing which transmitters (tubes) produces the greatest deviation in the beam when you speak into it – i.e. which tube should be the best transmitter. The small diameter tubes produce the best modulation; but they have the least reflective surface to send back the modulated light!

I play around with trying out a better pre-amplifier to boost the signals and also trying to use more than one detector (transistor with the top removed). The tests in the mine shaft showed the principle but the quality of the transmission was poor. Kathy and I go outside to use the bright sunlight and find that not only does it work but the quality is great. I guess we need light coming from all the surface of the foil rather than one spot of it. So we have a working system but in true RS fashion the range is very limited and the clouds are building up – just what we need!

On the way back from the mine shaft we see the most spectacular rain storm over the valley – at times almost blocking out the view of the mountains in the distance. Swirls of misty clouds with sunbeams coming through like the spokes from the glorious wheel of the desert Sun.

On the way back tonight Mike B, Iain and I discuss what should be on the plaque. There's all sorts of good ideas and I suggest that it should contain the letters H, E , L and P running down the middle but Mike B's suggestion was funny - he said the message to the alien life should read "what is the recipe for gypsum" (because Iain had problems making gypsum.)