Space Navigation

In space a successfully navigated craft must not only reach its intended destination, but must arrive there at the right time for rendezvous, and with a suitable velocity vector. Power limitations impose severe restrictions upon the amount of maneuvering that can be performed. Navigation techniques differ somewhat during the escape phase, in the vicinity of a planet and its natural satellites, during the midcourse phase of an interplanetary flight, and during the terminal phase. The most useful coordinate system is radius from a celestial body and some form of "latitude" and "longitude" on the sphere thus defined. Quantities measured are speed, direction, distance, acceleration, angles, and time. Of these, speed and direction of travel cannot now be measured to navigational accuracy. Position in space can be determined electronically, optically, and by inertial navigation, each under suitable conditions. Use of physical phenomena is not promising. A general-purpsoe digital computer will be needed. No order of magnitude improvement in state of the art is needed to produce a first-generation fully automatic space-navigation system, but considerable development work is required.