The science instruments aboard Hubble are large, complex
devices. Some are similar in size and shape to a telephone
booth and others are similar to a grand piano. The telescope
was designed to hold four telephone booth-sized instruments
and four piano-shaped instruments. The latter includes three
Fine Guidance Sensors, which can also collect science data.
The instruments take electronic pictures of stars and send
the picture data to the ground where scientists analyze the
information to make discoveries about our universe.
This picture shows an astronaut removing the Goddard High
Resolution Spectrograph in preparation for a new instrument
during the Second Servicing Mission.