The Galileo spacecraft sends us amazing images of other worlds -- erupting volcanoes, giant
icebergs, and furious storms. The images of Jupiter and its moons -- as well as other scientific
information -- are sent out from the spacecraft as digital code.
The onboard computer converts information from the scientific instruments into binary code ---
zero's and one's --- called bits. A flow of digital data -- a bitstream -- is sent from the spacecraft's
radio transmitter to the Deep Space Network
antennas.
But the signals carrying the information to Earth are very faint, and the farther they travel,
the weaker they get. Millions of miles away, the giant antennas of the Deep Space Network
capture the faint whisper of the bitstream. There is a background of natural radio noise that
threatens to drown out the spacecraft signal, so the Deep Space Network uses sensitive receivers
and powerful amplifiers to separate the radio signals from the noise.
The signals are converted into data for image-processing experts to reassemble them into
pictures of faraway, mysterious worlds.
