VLF electric and magnetic fields observed with the Javelin 8.45 Sounding Rocket

A rocket VLF experiment flown from Wallops Island to an altitude of 763 km is described, and the experiment results are discussed. A noise band between about 7.5 and 30 kHz was observed with both the electric and magnetic receivers. The field geometry of this noise suggests that the noise is propagating perpendicular to the geomagnetic field and that the lower cutoff frequency may be the lower hybrid resonance frequency. Intense noise bursts below 1 kHz were observed on the electric antennas below 500-km altitude during both the upgoing and downgoing portions of the flight, but not on the loop antennas. The precession and spin modulation of this noise is not consistent with an interpretation of these noise bursts as being due to long wavelength electrostatic waves in the surrounding plasma. We suggest that this electric antenna noise may be generated by the motion of the payload. The magnitude of the electric antenna impedance varied from a minimum of about 150 kilohms at 350-km altitude to about 600 kilohms at apogee. A large phase perturbation, usually inductive, was observed at altitudes below about 500 km whenever the antenna was aligned nearly parallel to the geomagnetic field. The electric field signal from the nosecone transmitter was attenuated much more rapidly than the magnetic field.