Progress 2

Progress 2 (Прогресс 2) was an unmanned Progress cargo spacecraft launched by the Soviet Union in 1978 to resupply the Salyut 6 space station. It used the Progress 7K-TG configuration, and was the second Progress mission to Salyut 6. It carried supplies for the EO-2 crew aboard Salyut 6, as well as equipment for conducting scientific research, and fuel for adjusting the station's orbit and performing manoeuvres.

Spacecraft
Progress 2 was a Progress 7K-TG spacecraft. The second of forty three to be launched, it had the serial number 101. The Progress 7K-TG spacecraft was the first generation Progress, derived from the Soyuz 7K-T and intended for unmanned logistics missions to space stations in support of the Salyut programme. On some missions the spacecraft were also used to adjust the orbit of the space station.

The Progress spacecraft had a dry mass of 6520 kg, which increased to around 7020 kg when fully fuelled. It measured 7.48 m in length, and 2.72 m in diameter. Each spacecraft could accommodate up to 2500 kg of payload, consisting of dry cargo and propellant. The spacecraft were powered by chemical batteries, and could operate in free flight for up to three days, remaining docked to the station for up to thirty.

Launch and docking
Progress 2 was launched at 11:26:16 UTC on 7 July 1978, atop a Soyuz-U 11A511U carrier rocket flying from Site 31/6 at the Baikonur Cosmodrome in the Kazakh Soviet Socialist Republic. The rocket that launched it had the serial number S15000-128. Following launch, Progress 2 was given the COSPAR designation 1978-070A, whilst NORAD assigned it the Satellite Catalog Number 10979.

Following launch, Progress 2 began two days of free flight. It subsequently docked with the aft port of the Salyut 6 space station at 12:58:59 UTC on 9 July. At the time of its docking, Soyuz 29 was docked to the forward port of the station. Soyuz 29 remained docked throughout the time Progress 2 was docked.

Mission
Progress 2 was the second of twelve Progress spacecraft used to supply the Salyut 6 space station between 1978 and 1981. It delivered cargo to the station, including Kristall a kiln used for experiments aboard the outpost. Progress 2 also transferred 600 kg of propellant into Salyut 6's tanks. Whilst Progress 2 was docked, Salyut 6 was manned by the EO-2 crew, consisting of cosmonauts Vladimir Kovalyonok and Aleksandr Ivanchenkov.

On 29 July 1978, whilst docked to Salyut 6, Progress 2 was catalogued in a low Earth orbit with a perigee of 327 km and an apogee of 330 km, inclined at 51.66° and with a period of 91.1 minutes. Progress 2 undocked from Salyut 6 at 04:57:44 UTC on 2 August. It remained in orbit until the early morning of 4 August 1978, when it was deorbited. The deorbit burn occurred at 01:31:07 UTC, with the spacecraft undergoing a destructive reentry at around 02:15 UTC. Less than four days after Progress 2 had been deorbited, Progress 3 was launched to replace it.