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DE 1 VLF observations during Activny wave injection experimentsWe report on coordinated high-altitude satellite observations in support of one of the first space-based very low frequency (VLF) wave injection experiments, namely the USSR Aktivny mission. The Aktivny satellite (A) was designed to carry a VLF transmitter (nominal frequency approximately 10 kHz, transmitter power approximately 10 kW) coupled to a 20-m-diameter loop antenna in a nearly polar orbit (83 deg inclination, apogee approximately 2500 km, perigee approximately 500 km). We focus our attention on conjunction experiments between the Aktivny and DE 1 satellites. Because of problems in the deployment of the loop antenna, the radiated power capability of the antenna was significantly reduced. Although this substantially reduced the expectation of receiving detectable signal levels on the satellite, the DE 1/Aktivny conjunction experiments were nevertheless carried out as a means of possibly placing an upper limit on the radiated power. During the period November 1989 through April 1990, a total of 10 DE 1/Aktivny wave injection sessions were conducted. During each session the Aktivny transmitter operated at 10.537 kHz with 1 s On - 1 s Off format, for a period of 6 min centered around the conjunction time. During three conjunction periods (December 12, 26, and 27, 1989) both DE 1 and Aktivny were in the southern hemisphere, and DE 1 was at relatively low altitudes (ranging from 6211 to 14,810 km), thus providing the best conjunction possibilities according to the ray tracing criteria developed above. On most days, Omega transmitter signals as well as commonly occuring natural wave phenomena such as whistlers (0(+)) and hiss were clearly seen well above the background level, but there was no evidence of the Aktivny 1 s On/ 1 s Off pattern. Though no Aktivny signals were detected by the LWR on the DE 1 satellite, the experimental constraints allow us to place an upper limit on the total power radiated by the Aktivny transmitter in the whistler-mode. Using experimental parameters, and the minimum detectable signal level of 0.05 muV/m for LWR, we find the upper limit on the total power radiated by the Aktivny satellite in the whistler-mode to be approximately 10 mW. Several recommendations for future space-based wave injection experiments are presented.
Document ID
19950029569
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Sonwalkar, V. S.
(Stanford Univ. Stanford, CA, United States)
Inan, U. S.
(Stanford Univ. Stanford, CA, United States)
Bell, T. F.
(Stanford Univ. Stanford, CA, United States)
Helliwell, R. A.
(Stanford Univ. Stanford, CA, United States)
Molchanov, O. A.
(Russian Academy of Sciences Moscow, Russia)
Green, J. L.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
August 16, 2013
Publication Date
April 1, 1994
Publication Information
Publication: Journal of Geophysical Research
Volume: 99
Issue: A4
ISSN: 0148-0227
Subject Category
Geophysics
Accession Number
95A61168
Funding Number(s)
CONTRACT_GRANT: NAG5-476
Distribution Limits
Public
Copyright
Other

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