Alouette-2 was a small space based ionospheric observatory instrumented
with a sweep-frequency ionospheric sounder (radio transmitter), a VLF radio
receiver, an energetic particle detector experiment, ... a cosmic radio noise
experiment, and an electrostatic plasma probe.
EXTERIOR ANTENNAS: The spacecraft used two long dipole antennas
(73 meter and 22.8 meter, respectively) for the sounder, VLF, and radio
cosmic noise experiments.
SPACECRAFT ROTATION (SPIN): The satellite was spin-stabilized at
about 2.25 rpm after antenna deployment. End plates on the 73 meter
antenna corrected the rapid despin that had occurred on the predecessor
spacecraft, Alouette 1, and which was believed to result from thermal
distortion of the antenna and from radiation pressure.
DATA ACQUISITION: There was no onboard tape recorder, so that data
were available to the ground receiving station only when the spacecraft
was in direct line of sight of telemetry stations. Telemetry stations
were located so that primary data coverage was near the 80 degrees
West meridan plus areas near Hawaii, Singapore, Australia, England,
India, Norway and Central Africa. Initially data were recorded about
8 hours per day. Degradation of the power supply system had, by June
1975, reduced the operating time to about 1/2 hour per day. Routine
operations were terminated in July 1975. The spacecraft was also
successfully reactivated on November 28 and 29, 1975, in order to
obtain data on its 10th anniversary.