Rama was first picked up by radar as asteroid 31/439 while still outside the orbit of Jupiter; and it was only when it was realised that it had a diameter of some twelve miles and that its course might completely upset the delicate balance of the solar system that scientists became at first intrigued and then worried. A space-probe was launched on a high-speed trajectory to intercept the mysterious intruder and to photograph it. Seven weeks after the probe’s launch, the pictures it transmitted brought to a halt the activities of most of mankind…