The Penguin Prophylactic Body-Loading Suit, in use from 1978-present, looked like the standard Russian blue inflight suit, but had additional elastic bands and pulleys that created artificial force against which the body could work, ameliorating the deterioration of muscles and bones that occurs in long-term zero gravity. The Penguin suit was routinely worn during all long-term flights.

• 1971 March 21 - DOS communications tests at Baikonur - Program: Salyut. Flight: Soyuz 10, Soyuz 11, Soyuz 12 / DOS 1.

  Due to problems with the electrical system aboard the station, the crews are unable to start their training aboard the actual station until 22:00. So after breakfast they work on their flight plans and logs and test the training suits to be used on this flight for the first time. This includes the Penguin suit which has elastic bands sewn into it to simulate the strain of gravity. At 17:00 the crews go to the MIK and start communications tests on the DOS. All proceeds normally. On the bus back, the crews discuss the new tracking ship Yuri Gagarin. It has a displacement of 45,000 tonnes and cost 120 million roubles. It will expand the time communications are possible with the ground during the long station flight.

• Kamanin, N P, Skritiy kosmos, Infortext, Moscow, 1995. The diary of the Commander of the Soviet Cosmonaut Team in the 1960's - a source of great insights into the space program. Four volumes issued to date.