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Shenzhou 5 reentry capsule
A reentry capsule is the portion of a spacecraft which returns
to Earth following a space flight. The shape is determined partly
by aerodynamics; a
capsule is aerodynamically stable falling blunt end first, which
allows only the blunt end to require a heat shield for atmospheric
reentry. Its shape has also been compared to that of an
old-fashioned automobile's headlight. A manned capsule contains the
spacecraft's instrument panel, limited storage space, and seats for
crew members. Because a capsule shape has little aerodynamic lift, the final descent is via
parachute, either coming
to rest on land, at sea, or by active capture by another aircraft.
In contrast, the development of spaceplane reentry vehicles attempts to
provide a more flexible reentry profile.
Shenzhou
The reentry capsule is the "middle" module of the three-part
Soyuz or Shenzhou spacecraft – the orbital module is located at the
front of the spacecraft, with the service or equipment module attached to
the rear. A feature in the landing system allows the use of a
single parachute and "braking rocket,"
thus the heatshield is dropped from the spacecraft similar to the
landing bag deployment on the U.S. Mercury spacecraft. Like the Command Module of the Apollo
spacecraft, the Shenzhou reentry capsule has no reusable
capabilities; each spacecraft is flown once and then "thrown away"
(usually sent to museums).
Few details are known about the Shenzhou reentry capsule, except
that it uses some technology from the Soyuz TM design. The new
Soyuz TMA spacecraft, now used solely for International Space Station
flights, had its couches modified to allow for taller crewmembers
to fly, and features "glass cockpit" technology similar to that
found on the Space
Shuttle and newer commercial and military aircraft.
Although no Chinese casualties have occurred on the few flights
of the Shenzhou reentry capsule, the former Soviet Union suffered
two disasters, and one near-disaster, all three involving the
capsule during the de-orbit and reentry. Soyuz 1 ended in disaster when the parachutes
failed to deploy and the capsule smashed into the earth at speeds
over 300 mph, killing cosmonaut Vladimir Komarov. Soyuz 5 almost ended in
disaster, when the reentry capsule entered the atmosphere on the
wrong end – attributed to a failure of the equipment module to
separate similar to that on the Vostok 1 flight. Luckily, the equipment module
burned off the descent module and the capsule righted itself.
Soyuz
Soyuz 11 ended in
disaster in 1971 when an equalization valve, used to equalize air
pressure during the Soyuz final descent, prematurely opened in the
vacuum of space, killing the three crew members, who were not
wearing spacesuits. Subsequent flights, from Soyuz 12 to Soyuz 40, utilized a two-man
crew because the third seat had to be removed for the pressure suit
controls. The Soyuz T version restored the third seat.
List of
reentry capsules
-
This list is incomplete; you can
help by expanding it.
References
See also
Apollo Command Module
Orbital
Vehicle
Shenzhou re-entry module
Soyuz reentry module
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