We know a great deal about historical climate and its variations from various geo logical studies. There are two points worth remarking on. One is that the climate changes frequently and radically, but that the degree of variation and even sense of variation depends on the time scale which we are considering. Secondly, that this is a most unusual geological period for the Planet Earth; we are living in a period of mountain building and glaciations, whereas during most of the last 250 million years (m.y.) there was little ice and little topography. A good view of climate change of the last...

The publication of this book is extremely timely, for the next major advances in manned space flight after Project Apollo will most likely be made in earth orbital operations. Manned exploration of the moon will certainly continue after the initial landing, but it will be performed essentially with the Saturn V launch vehicles and Apollo spacecraft developed in Apollo, especially in the early phases. Modifications to this basic hardware will increase operating capabilities to permit extensive lunar explo ration during prolonged stay times by the astronauts on the moon's surface. Manned...