Institute for Telecommunication Sciences / September 1962
On September 29, 1962, the world’s first top-side ionospheric sounding satellite was launched from Point Aguella Missile Range in California. Top-side sounding allows researchers to probe the ionosphere from above, in much the same way that researchers have explored it from the ground, using reflected radio waves. These readings improve ionospheric maps, which are essential for radio communications, and help scientists understand the charged layers of the atmosphere that reflect and scatter radio waves. Allouette (French for lark) was constructed at Canada’s Defence and Research Telecommunications Establishment (DRTE) by a team headed by scientist John Chapman. DRTE joined with the UK’s Radio and Space Research Station, NASA, and the Central Radio Propagation Lab (CRPL) in the International Satellites for Ionospheric Sounding program in 1959. The cooperative research group had already launched two American rockets equipped with fixed frequency transmitters to probe the ionosphere as they passed through during their 13 minute flights. Allouette, which was launched on a two stage Thor-Agena rocket and placed into a 1000 km, circular orbit remained in space for 10 years, and sent over one million images back to earth. The satellite passed over CRPL’s headquarters in Boulder, Colorado weekly. CRPL’s analysis of Allouette’s data was instrumental in understanding Spread F, the scattering of radio waves by moving plasma within the ionosphere. ITS’s current research into radio propagation and spectrum utilization relies heavily on data obtained from Allouette and similar projects from the 1960s.