Astronautics and Guided flight section

Extract

I shall discuss two examples of possible future deep space missions but first of all let me fill in a little of the scientific background in order to give you some idea of the kind of questions that we would aim to answer by undertaking these projects. It is now rather more than twelve years since the first spacecraft were placed in independent orbit round the sun. These were Lunik I and Pioneer IV which were the first satellites to make measurements in space outside the earth's gravitational field. In these twelve years as a result of the succession of space probes which has followed we have learned a great deal about the physics of interplanetary space where the situation is dominated by the solar wind and magnetic fields which it carries out from the lower corona. Let me remind you of the salient facts.