Salyut 5
Expedition 2

Launch from the Baikonur Cosmodrome and landing 36 km northeast of Arkalyk.

Following a one-day solo flight Soyuz 24 docked with the space station Salyut 5 on February 08, 1977. However, the crew did not immediately enter the station, atypically having a sleep period first and delaying their entry by some 11 hours. Observers speculate that problems with fumes which may have caused the Soyuz 21 crew to leave were resolved or dealt with by the new crew. They entered the station wearing breathing apparatus and made numerous tests of the atmosphere before apparently concluding conditions were safe and removing their breathing devices.

The crew brought repairing tools and equipment for changing of cabin atmosphere. This special apparatus was designed to allow the entire station to be vented through the EVA airlock. Because of this the planned EVA was cancelled. On February 21, 1977, the crew performed an air-changing experiment, shown on TV, slowly venting air from one end of the station to the other while releasing 100 kg of air from tanks in the docked Soyuz orbital module. This was a test of the future air replenishment techniques to be carried out with Progress transports in subsequent space stations. The cabin air was not toxic, so the changing of cabin atmosphere was performed as a scientific experiment.

The crew continued the research started by the Soyuz 21 crew, performed Earth resources work, biological and materials experiments. But, being a part of the Almaz military Salyut program, other unrevealed projects were likely carried out. The flight would prove to be not only the final flight to a military Salyut station, but also the final all-military crew to be launched by the Soviets.

The Soyuz spacecraft is composed of three elements attached end-to-end - the Orbital Module, the Descent Module and the Instrumentation/Propulsion Module. The crew occupied the central element, the Descent Module. The other two modules are jettisoned prior to re-entry. They burn up in the atmosphere, so only the Descent Module returned to Earth.
Having shed two-thirds of its mass, the Soyuz reached Entry Interface - a point 400,000 feet (121.9 kilometers) above the Earth, where friction due to the thickening atmosphere began to heat its outer surfaces. With only 23 minutes left before it lands on the grassy plains of central Asia, attention in the module turned to slowing its rate of descent.
Eight minutes later, the spacecraft was streaking through the sky at a rate of 755 feet (230 meters) per second. Before it touched down, its speed slowed to only 5 feet (1.5 meter) per second, and it lands at an even lower speed than that. Several onboard features ensure that the vehicle and crew land safely and in relative comfort.
Four parachutes, deployed 15 minutes before landing, dramatically slowed the vehicle's rate of descent. Two pilot parachutes were the first to be released, and a drogue chute attached to the second one followed immediately after. The drogue, measuring 24 square meters (258 square feet) in area, slowed the rate of descent from 755 feet (230 meters) per second to 262 feet (80 meters) per second.
The main parachute was the last to emerge. It is the largest chute, with a surface area of 10,764 square feet (1,000 square meters). Its harnesses shifted the vehicle's attitude to a 30-degree angle relative to the ground, dissipating heat, and then shifted it again to a straight vertical descent prior to landing.
The main chute slowed the Soyuz to a descent rate of only 24 feet (7.3 meters) per second, which is still too fast for a comfortable landing. One second before touchdown, two sets of three small engines on the bottom of the vehicle fired, slowing the vehicle to soften the landing.