Earth-observation cameras

The work compartment was dominated by the Agat-1 Earth-observation telescope, which had a focal length of 6.375 metres and an optical resolution better than three metres, according to post-Soviet sources;^[9] NASA historian Siddiqi has speculated that given the size of the telescope's mirror, it likely had a resolution better than one metre.^[10] The telescope was used in conjunction with a wide-film camera and primarily for military reconnaissance.^[11] The cosmonauts are said to have observed targets set out on the ground at Baikonur. Secondary objectives included the study of water pollution, agricultural land, possible ore-bearing landforms, and oceanic ice formation.^[8]

The cosmonauts were able to develop film while on the station. Important or interesting images were printed and then scanned by a TV imaging system for broadcast to Earth.^[8] They needed as little as 30 minutes to shoot, develop, and scan a photograph.^[8] Less important images were packed into a small Earth-return capsule, which could be ejected from the station.^[8]

In addition to the Agat-1 camera, other cameras on board included a topographical camera, a star camera, and a Volga infrared camera with a resolution of 100 metres.^[1] Cosmonaut Pavel Popovich, who visited the station as the commander of Soyuz 14, recalled that the station was equipped with 14 cameras.^[1]

On-board gun

The Salyut 3, although called a "civilian" station, was equipped with a "self-defence" gun which had been designed for use aboard the station, and whose design is attributed to Alexander Nudelman.^[1] Some accounts claim the station was equipped with a Nudelman-Rikhter "Vulkan" gun, which was a variant of the 23 mm Nudelman aircraft cannon, or possibly a Nudelman NR-30 30 mm gun.^[12] Later Russian sources indicate that the gun was the virtually unknown (in the West) Rikhter R-23.^[13] These claims have reportedly been verified by Pavel Popovich, who had visited the station in orbit, as commander of Soyuz 14.^[12] Due to the potential shaking of the station, in-orbit tests of the weapon with cosmonauts in the station were ruled out.^[1] The gun was fixed to the station in such a way that the only way to aim would have been to change the orientation of the entire station.^[1][12] Following the last crewed mission to the station, the gun was commanded by the ground to be fired; some sources say it was fired to depletion,^[12] while other sources say three test firings took place during the Salyut 3 mission.^[1]

Launch

The station was launched on 25 June 1974 by a three-stage Proton launch vehicle.^[2]

Salyut 3 was the first space station to maintain its constant orientation relative to the Earth's surface.^[1] To achieve that, as many as 500,000 firings of the attitude control thrusters had been performed.^[1] Its initial orbit was 219 km by 270 km above mean sea level, which was considered low.^[3] The suspicions of Western observers were raised by the low altitude, combined with the choice of a crew from the Soviet Air Force, and the use of radio frequencies normally designated for military use.^[3]

Soyuz 14

On 4 July, a little over a week after Salyut 3 was launched, the crewed spacecraft Soyuz 14 docked with the station, having been launched the previous day.^[14] The crew of Soyuz 14 consisted of commander Pavel Popovich and flight engineer Yury Artyukhin. The crew spent 15 days aboard the station.

On 9 July, it was reported that the crew activated the Earth-observation cameras, and spent several days taking photos of various locations, including central Asia.^[1] They placed some film in the Earth return capsule.^[1] After undocking, Soyuz 14 safely landed on 19 July.^[14]

Soyuz 15

The spacecraft Soyuz 15 was launched on 26 August 1974, carrying a two-man crew consisting of commander Gennadi Sarafanov and flight engineer Lev Demin.^[1] They were intended to be the second crew to man Salyut 3, but failed to dock. The Igla rendezvous system on their Soyuz spacecraft malfunctioned, and the crew was unable to dock manually.^[15] Due to the limited battery life of their Soyuz spacecraft, they de-orbited and landed two days after launch.^[15] At the time of the spaceflight, Demin was 48 years old, earning him the record for the oldest person to fly in space up to that point.^[16] This record was broken the following year, with Deke Slayton's spaceflight as a part of the Apollo–Soyuz Test Project.^[16]

Uncrewed operations

Following the failed docking of Soyuz 15, it was decided that the Igla docking system needed significant modifications.^[16] Due to the amount of time needed to make the changes, and the limited time Salyut 3 had left in orbit due to orbital decay, the next planned mission to the station was cancelled.^[16] The spacecraft which would have been used on the third mission to Salyut 3 was later used for the mission Soyuz 20 to Salyut 4 (a civilian space station).^[16]

Following this decision, on 23 September 1974, the station's Earth return capsule was released. The ejected capsule was deorbited by small engines. NASA sources report that the parachute of Salyut 3's capsule opened at an altitude of 8.4 km.^[8] Other sources say the main parachute did not open, and the capsule was deformed upon landing, but that all the film was recoverable.^[17]

Also following the decision to not send any more cosmonauts to the station, the on-board gun was commanded by the ground to be fired; some sources say it was fired to depletion,^[12] while other sources say three test firings took place at the end of the mission.^[1]

The station was deorbited on 24 January 1975 over the Pacific Ocean.^[1]