Columbia Encyclopedia World Factbook Columbia Gazetteer American Heritage Coll. Space science draws on the conventional sciences of physics, chemistry, biology, and engineering, as well as requiring specific research of its own. The particular disciplines that are relevant depend on the type of mission being planned. There are four basic categories of space mission. Artificial satellites orbit the earth at altitudes between one hundred and several thousand miles.
Space probes travel to the moon and planets.
The final and most complex category is human spaceflight, of which the Apollo moon landings, the space shuttle , and the Skylab, Mir, and International space stations are the outstanding examples. The problems that space science must deal with include prediction and control of trajectories and orbits, telecommunications between spacecraft and earth, spacecraft design and fabrication, and life-support systems for human spaceflight. The key contribution of physics is celestial mechanics , the laws that govern the motions of bodies moving under the influence of gravitation. By combining Newton's law of universal gravitation and his laws of motion, the path of a rocket in the earth's vicinity can be calculated. This path, known as the trajectory, is strictly determined by the initial thrust imparted to the rocket, the gravitational field of the earth, and the atmospheric drag encountered.