Astronauts began to leave
the comfort and safety of their spacecraft and began floating in
space in 1965. This activity has been termed "space walking."
This activity is always risky because the astronauts have only a
few thin layers of fabric and plastic between them and the lethal
Surface space walking took
place on the moon during the Apollo missions of the late 1960's
and early 1970's. The astronauts wore self-contained
spacesuits and roamed across the lava plains and rugged highlands
of the Moon. On the last three missions that had a wheeled
transport vehicle called a Moon buggy.
In July 1990 Soviet Union
cosmonauts made two long space walks on the space station Mir to
check and repair their ferry craft and close a faulty reentry
Since the space shuttle was
introduced, many scheduled and a few unscheduled space walks have
taken place. Scheduled walks were made to repair satellites
that have been captured from orbit. Walks have also been
scheduled to support experiments taking place in the cargo
bay. While working in the cargo bay, the astronauts are
usually tethered to a safety line or "ride" on the
orbiter's robot arm. They wear a jet-propelled backpack know
as the manned maneuvering unit (MMU).