ISIS (satellite)

The ISIS satellites, short for International Satellites for Ionospheric Studies, were a series of Canadian scientific satellites developed in cooperation with NASA. Launched between 1965 and 1971, the ISIS program aimed to study the Earth's ionosphere and magnetosphere. The primary goal was to understand the structure and behavior of the ionosphere, a region of the upper atmosphere that plays a critical role in radio wave propagation.

Two satellites comprised the ISIS program: ISIS I and ISIS II.

• ISIS I (Alouette 3): Launched on January 30, 1969, ISIS I carried a suite of instruments designed to measure various ionospheric parameters, including electron density, electron temperature, and ion composition. It also carried experiments to study cosmic noise and radio wave propagation. ISIS I was known for its comprehensive set of instruments and its longevity, operating for over 20 years.

• ISIS II: Launched on April 1, 1971, ISIS II followed ISIS I, building on its predecessor's capabilities. ISIS II was distinguished by its ability to simultaneously observe auroral phenomena from both above and below, using a combination of optical and particle detectors. This allowed for a more complete understanding of the processes involved in auroral formation. It also included instruments to measure energetic particles and plasma waves.

The data collected by the ISIS satellites provided invaluable insights into the physics of the ionosphere and magnetosphere. This knowledge has contributed significantly to our understanding of radio communications, satellite drag, and space weather phenomena. The ISIS program is considered a major success story in international space collaboration and a testament to Canada's contributions to space science. The archived data from the ISIS missions continues to be used by researchers today.