I was 6,500 feet above sea level in the mountains of Inyanga in what was then known as Southern Rhodesia, lying on my back on the grass and looking up at the stars. They were always unbelievably clear and bright up there, and the first rains of the season had rinsed the dust and the smoke of bush fires from the sky. As always the Southern Cross and Orion’s shimmering sword belt dominated the heavens, but tonight I was looking for something else – something no one had ever seen before. Eventually I saw it – a tiny speck of light, smaller than many of the stars, travelling across the midnight sky. It was October 1957, and the Russians had just successfully launched Sputnik 1, the first artificial satellite.