Launch from the Baikonur Cosmodrome and
landing 60 km northeast of Arkalyk.
The main goal of the mission was to
repair the faulty
Salyut 7 solar array.
Once in orbit the
Soyuz rendezvous
radar antenna boom failed to
deploy properly. Several attitude control maneuvers at high rates were made but
failed to swing the boom out. (The postflight inquiry later discovered that the
antenna had been torn off when the
Soyuz payload shroud separated.) The crew believed the
boom remained attached to the spacecrafts orbital module, and that it had
not locked into place. Accordingly, they shook the spacecraft using its
attitude thrusters in an effort to rock it forward so it could lock. With FCC
permission, the crew attempted a rendezvous using only an optical sight and
ground radar inputs for guidance. During the final approach, which was made in
darkness, Vladimir
Titov believed that the closing speed was too great. He
therefore attempted a braking maneuver, but felt that the two spacecraft were
still closing too fast. He aborted the rendezvous to avoid a crash, and no
further attempts were made. The abortive docking attempts consumed much
propellant. To ensure that enough would remain to permit deorbit, the
cosmonauts shut down the attitude control system and put
Soyuz T-8 into a spin stabilized mode of the type used
by
Soyuz Ferries in the early 1970s. A premature return
to Earth was needed.
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.
The
deorbit burn lasted about 3 to 4 minutes. 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.
The landing then was
without problems.