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This
photo shows an astronaut holding a reel-to-reel
tape recorder prior to stowing it for return to
the ground. Hubble originally used reel-to-reel
tape recorders to store data that could not be
sent to the ground in real time. The on-board
recorders would record the engineering or science
data, and then the ground controllers would command
a playback or tape recorder dump at a later time
when communications permitted it.
During
the Second Servicing Mission, the first solid-state
recorder was installed, replacing one of the original
reel-to-reel recorders. A second recorder was
installed during Servicing Mission 3A. The new
recorders have no reels or tape and no moving
parts to wear out and limit lifetime. Data is
stored digitally in computer-like memory chips
until the ground controllers command the recorders
to play the data back to the ground.
The
new recorders are the same size as the reel-to-reel
tape recorders, but they store over 10 times more
data than the old recorders. The new recorders
can record two data streams at one time, so both
engineering and science data can be recorded.
In addition, data can be recorded and played back
at the same time.
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