Examination of very low frequency records of the Alouette 1 satellite has revealed the presence of an unusual band of noise. This band shows several features that distinguish it from other VLF emissions which are observed both in the satellite and on the ground. It is suggested that this noise is generated in the immediate vicinity of the satellite as a result of a resonance in the plasma surrounding the satellite. From a knowledge of the resonance frequency and the ambient plasma and gyrofrequencies, an inverse mean of the ionic mass can be determined.