The Canadian satellites Alouette 1 and 2 were small ionospheric observatories built as a joint project between Canada's Defence and Research Telecommunications Establishment (DRTE) and NASA. Alouette 1 was also the first Canadian satellite.
Alouette 1 was a small ionospheric observatory instrumented with an
ionospheric sounder, a VLF receiver, an energetic particle detector, and a cosmic noise
experiment. Extended from the satellite shell were two dipole antennas (45.7 m and 22.8 m
long, respectively) which were shared by three of the experiments on the spacecraft. The
satellite was spin-stabilized at about 1.4 rpm after antenna extension. After about 500
days, the spin slowed more than had been expected, to about 0.6 rpm when satellite
spin-stabilization failed. It is believed that the satellite gradually progressed toward a
gravity gradient stabilization with the longer antenna pointing earthward. Attitude
information was deduced only from a single magnetometer and temperature measurements on
the upper and lower heat shields. (Attitude determination could have been in error by as
much as 10 deg.) There was no tape recorder, so data were available only from the vicinity
of telemetry stations. Telemetry stations were located to provide primary data coverage
near the 80 deg W meridian and in areas near Hawaii, Singapore, Australia, Europe, and
Central Africa. Initially, data were recorded for about 6 h per day. In September 1972,
spacecraft operations were terminated.
Alouette 2 was a small ionospheric observatory instrumented with a
sweep-frequency ionospheric sounder, a VLF receiver, an energetic particle experiment, a
cosmic noise experiment, and an electrostatic probe. The spacecraft used two long dipole
antennas (73 m and 22.8 m, respectively) for the sounder, VLF, and cosmic noise
experiments. The satellite was spin-stabilized at about 2.25 rpm after antenna deployment.
End plates on the 73 m antenna corrected the rapid despin that had occurred on Alouette 1,
and which was believed to result from thermal distortion of the antenna and from radiation
pressure. There was no tape recorder, so that data were available only when the spacecraft
was in line of sight of telemetry stations. Telemetry stations were located so that
primary data coverage was near the 80 deg W meridan plus areas near Hawaii, Singapore,
Australia, the UK, India, Norway, and Central Africa. Initially data were recorded about 8
h per day. degradation of the power supply system had, by June 1975, reduced the operating
time to about 1/2 h per day. Routine operations were terminated in July 1975. The
spacecraft was successfully reactivated on November 28 and 29, 1975, in order to obtain
data on its 10th anniversary.
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