Short answers, pulled from the story.
Salyut 5, also known as OPS-3, was a Soviet military space station launched in 1976 as the third and final Almaz station. Its primary purpose was to conduct military experiments, including Earth observation using the Agat camera, though scientific research such as crystal growth and microgravity studies was also performed.
A fuel leak aboard Salyut 5 released nitric acid fumes into the station's atmosphere, degrading the physical and psychological condition of cosmonauts Boris Volynov and Vitali Zholobov. They made an emergency landing on the 24th of August 1976, roughly 200 kilometres southwest of Kokchetav, cutting short a mission that had been planned to run longer.
A faulty sensor falsely reported lateral motion during the approach on the 15th of October 1976. The automated Igla docking system fired the spacecraft's maneuvering thrusters to correct the non-existent motion, burning too much fuel for a manual docking attempt. Soyuz 23 returned to Earth on the 16th of October without completing its objectives.
Salyut 5 launched at 18:04:00 UTC on the 22nd of June 1976 from Site 81/23 at the Baikonur Cosmodrome, carried by a Proton-K rocket. It was deorbited on the 8th of August 1977, burning up on reentry after roughly fourteen months in orbit.
Two crewed missions successfully docked with Salyut 5: Soyuz 21 in July-August 1976 and Soyuz 24 in February 1977. Soyuz 23 attempted but failed to dock in October 1976, and a fourth planned mission was cancelled due to a propellant shortage aboard the station.
The spacecraft constructed for the planned fourth mission, which would have been designated Soyuz 25, was repurposed and flew instead as Soyuz 30 to the successor station Salyut 6. The cancellation was caused by Salyut 5 running low on propellant for its main engines and attitude control system.