Progress 7K-TG

Progress 7K-TG (Russian: Прогресс 7К-ТГ, GRAU index 11F615A15), was a Soviet uncrewed spacecraft used to resupply space stations in low Earth orbit.

The descent module of the Soyuz spacecraft was replaced with a new section designated Otsek Komponentov Dozapravki, or OKD.

Early spacecraft had a design life of 33 days, including three in free flight, and the rest docked with a space station.

Later spacecraft flew longer missions, with the longest, Progress 38, spending almost 75 days in orbit.

Officially this was done to preserve the rocket's aerodynamic properties, however it was reported that on several flights the tower was used to support tests of the K-36M ejection seat under development for the Buran programme.

Mockup of Salyut 7, with a docked Progress 7K-TG (right) and Soyuz 7K-T (left).