Space
Shuttle Basics
Orbit
After the main
engines shut down, the shuttle is in an egg-shaped orbit that, if
nothing changed, would cause it to re-enter the atmosphere above
the Pacific Ocean, the same as what happens to the external fuel
tank. But, about 35 minutes after the main engines have shut down,
usually when the shuttle has reached the highest point of the egg-shaped
orbit, the two orbital maneuvering system engines, located on the
left and right side of the shuttle's tail, are fired for about three
minutes. The orbital maneuvering system engines use two propellants
that automatically burn whenever they contact one another, and the
three-minute firing circularizes the shuttle's orbit at a safe altitude,
one that will keep it above the atmosphere.
 | | An
orbital maneuvering system engine firing caused this bright
glow at the aft end of the shuttle during STS-7. |
The shuttle
is the only spacecraft ever built that can retrieve large satellites
from orbit and bring them back to Earth. Using the Canadian-built
robotic arm, called the Remote Manipulator System, mounted on the
left-hand edge of the cargo bay, shuttle crews can move large objects
into or out of the payload bay. The arm also can maneuver spacewalking
astronauts into positions for satellite repairs and maintenance,
as have been performed on the Hubble Space Telescope, or space construction,
as is being conducted for the International Space Station.
The largest
shuttle crew ever flown numbered eight people, but the average crew
ranges from five to seven people. Crew members include pilot astronauts,
called the commander and pilot who fly the shuttle, and mission
specialist astronauts who are scientists and engineers trained to
conduct the experiments onboard or perform specific tasks in orbit.
Occasionally, the crew also may include payload specialist astronauts
in charge of the operations of a specific cargo. The shuttle can
launch as much as 28,803 kilograms (63,500 pounds) of cargo into
orbit. It has remained in orbit for as long as 17 days before returning
to Earth.
 | | Upfiring
of the shuttle's reaction control system. |
Eating, sleeping
and personal hygiene equipment are located on the lower deck of
the shuttle, called the middeck. The top deck, called the flight
deck, is the shuttle cockpit, with flight controls located on both
the front and back walls. A small lower "deck," called the equipment
bay, is inaccessible unless the floor panels of the middeck are
lifted up. This under-floor area houses avionics equipment, electronics
equipment and a trash compartment. The crew cabin's total pressurized
volume is about 74.3 cubic meters (2,625 cubic feet). The cabin
includes a circular side hatch, about a meter (3 feet) in diameter,
that is used for entry and exit from the shuttle before launch and
after landing.
The shuttle's
airlock, used to seal spacewalkers off from the rest of the cabin
and depressurize to begin an extravehicular activity, is located
in the payload bay just aft of the main cabin and attached to the
middeck by a short tunnel. An inner airlock hatch can be closed
to seal the lock from the rest of the cabin. An outer hatch can
be opened to exit into space. The airlock's volume is about 4.24
cubic meters (150 cubic feet). A docking mechanism to attach to
the International Space Station is located atop the airlock.
Flight
portrait and post-flight
portrait of the STS-82 crew. The solar arrays of the Hubble
Space Telescope are visible behind the STS-82 crew in their flight
portrait. The shuttle Discovery is directly behind the crew in their
post-flight portrait.
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