Chalet/Vortex was the second generation of United States Air Force SIGINT (signals intelligence) satellites, launched between 1978 and 1989, that superceded Canyon and Rhyolite/Aquacade. The program was renamed Vortex after the code name Chalet appeared in The New York Times. It was superceded by Magnum and Mercury ELINT.


Chalet/Vortex was even larger than Rhyolite, weighing around 1800 kg and having a 38-m diameter antenna. Its primary mission was to intercept communications carried on UHF radio links which used antennae directed towards stationary orbit, or antennae with wide main lobes. There were six launches in total: Chalet-1 (June 10, 1978) and Vortex 1–5 (October 1, 1979–May 10, 1989). The second batch of three Vortex satellites, launched from 1984 to 1989, probably had enhanced sensors. One was stranded in the wrong orbit when its Titan Transstage (transfer stage) malfunctioned. Each Chalet/Vortex satellite had a nominal lifetime of 5 to 7 years.


launch vehicle Titan-3C and -34D
site Cape Canaveral
orbit quasi-GSO
32,940 × 38,330 km × 5.5°
size 38.4 × 36.6 m
mass 1,800 kg