The Orbital X-Band Real-Aperture Side-Looking Radar of Cosmos-1500: A Ukrainian IEEE Milestone candidate

We revisit the development and operation of the orbital X-band real-aperture side-looking radar (RA-SLR) onboard the USSR satellite Cosmos-1500 in the historical context. This radar was conceived, designed, and tested in the early 1980s and then supervised, in orbit, by a team of Ukrainian scientists and engineers led by Prof. Anatoly I. Kalmykov (1936–1996) at the O. Y. Usikov Institute of Radiophysics and Electronics (IRE) of the National Academy of Sciences of Ukraine (NASU). It had a magnetron source, a 12-m deployable slotted-waveguide antenna, and an onboard signal processing unit. Instead of preplanned meticulous experiments, only five days after placement into the polar Earth orbit in the autumn of 1983, the SLR of Cosmos-1500 rendered truly outstanding service. It provided a stream of microwave images of the polar sea ice conditions that enabled the rescue of freighters in the Arctic Ocean. Two years later, similar imagery was equally important in the rescue of a motor vessel (MV) in the Antarctic. However, the way to success was far from smooth. Besides the technical problems, Kalmykov had to overcome the jealousy and hostility of his home institute administration, colleagues from Moscow research laboratories, and high-level USSR bureaucracy. Later, Kalmykov’s radar was released to the industry and became the main instrument of the USSR and Russian series of remote sensing satellites Okean and Ukrainian satellites Sich-1 and Sich-1M. We believe that the RA-SLR of Cosmos-1500 is a good candidate for the status of an IEEE Milestone in Ukraine.