On Salyut 6, each two-man crew had used up 20 to 30 kilograms of consumables per day. For a station to be continuously inhabited, the logistical system would require to deliver 1 tonne of consumables per month, which meant one Progress flight every two months. However, the longer life of the Soyuz-T would reduce the need to send up crews on brief visits to exchange ferries, which meant that the pace of operations should be considerably less hectic than that which had been sustained while Salyut 6 was occupied. One objective of the next station would be to have one crew hand the station over to its successor. This could have been done on Salyut 6 if a retiring crew had departed in its own ferry and left the new residents with their own. A handover in orbit would eliminate the time wasted in powering down and then reactivating the station, and would facilitate a lengthy period of occupation without requiring a single crew to endure the stress of an extended flight. And, if the life-support system could sustain three people, it would also facilitate partial crew exchanges, and even allow a research cosmonaut to serve with successive crews to carry out an extended study of adaptation to weightlessness.