3000mm to 4000mm. This could give a resolution of 0.5m, although there is some evidence that the lens diameter was only 420mm, which would reduce the ground resolution to only 0.7m. The lens was retractable and had a cover which only opened when the camera was taking photographs. The film type is unknown but might be the same as in the Zenit, which had 300mm x 300mm frames. The camera was developed by the Krasnogorsk Optical-Mechanical Plant (KMZ). The satellite de-orbited by retracting the lens into the special equipment module. The other two modules and the lens shade separated and burnt up in the atmosphere. The reentry vehicle then landed on the ground. The computer and camera were designed to be reusable. The craft contained a self-destruct mechanism. Operation The first test launch of a Yantar-2K was on 23 May 1974 which ended in launch failure and the loss of the satellite. The second flight, on 13 December 1974, was successful and Kosmos 697 landed after 12 days. After seven test launches the satellite was taken into service with the first one on 5 August 1978. There were thirty launches in total, including test launches, with the last one on 28 June 1983. Yantar-2K was replaced by the similar Yantar-4K1, named Oktan. It had its first test launch on 27 April 1979 and had its first operational flight in 1982. References Yantar (satellite)