Voyage to Mars

Abstract

This book is not concerned with a journey to Mars. The method of travel has not yet been chosen, and the hardware has not yet been planned or defined. Mars is a near-neighbour of Earth, and there are times when Mars approaches relatively close to us (though still not as close as Venus); but the problem is that a spacecraft cannot just ‘zip’ across the intervening gap between the worlds. It might be thought that a launch could be timed to coincide with the close approach of Mars to Earth, and that a rocket could be launched from Earth’s surface and aimed at Mars, and then fire its engines all the way until it arrives. But it is not that simple. The distance from Earth to Mars is 56 million km even at such favourable times, and no current rocket can carry enough fuel and oxidiser (propellants) to sustain continuous engine-firing. The planets are also moving around the Sun, and are moving at different speeds. The spacecraft becomes another body orbiting the Sun, and has to go where the Sun’s powerful gravity will allow it.