Abstract
The design and construction of a complete system for the accurate determination of the earth's magnetic field in a rocket vehicle are described. The flight equipment utilizes the principle of proton-free precession to produce a frequency analogue of the intensity of the geomagnetic field; this frequency is independent of the attitude of the rocket. Some special features of the instrument which are necessary to make it perform satisfactorily in the severe environmental conditions of a rocket flight are discussed in detail. During play-back of the telemetered and recorded precession signals the ground equipment described improves the quality of the data and converts them to a form more suitable for analysis and interpretation.The results of the first instrument-proving flight are presented and briefly discussed