Nowadays, many small satellites developed for universities and technology development projects use amateur radio frequencies and AX.25 link layer protocol 3, 4. Radio amateurs have been building and tracking satellites since 1961 2. The radio onboard Longjiang-2 is the first radio communication system operating on amateur radio bands that was placed into lunar orbit. The logic on Longjiang-2 was later patched, and after 113 h of flight since launch, the satellite successfully inserted itself into a lunar elliptical orbit of 357 km × 13704 km, and became the smallest spacecraft which entered lunar orbit independently.īesides the S-band and X-band radios operated by the Chinese Deep Space Network (CDSN), Longjiang-1 and Longjiang-2 were equipped with identical VHF/UHF radios for amateur radio experiments and backup tracking, telemetry, and command (TT&C). Unfortunately, Longjiang-1 was lost because of a malfunction of thruster control logic during the first trajectory correction maneuver (TCM). The satellites, each with a volume of 765 × 420 × 570 mm 3 and a mass of ~47 kg, were launched into a lunar transfer orbit on by a CZ-4C rocket as secondary payloads, together with the Queqiao L2 relay satellite. Longjiang-1 and Longjiang-2 are a pair of lunar micro-satellites for low-frequency radio astronomy, amateur radio, and education, developed by Harbin Institute of Technology, as a part of the Chang’e-4 lunar far side mission 1.
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