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National Aeronautics and Space Administration

Goddard Space Flight Center

Astrophysics Science Division | Sciences and Exploration

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THE HUBBLE SPACE TELESCOPE
OVERVIEW HUBBLE NEWS OPERATIONS TECHNOLOGY SERVICING MISSIONS HUBBLE MULTIMEDIA PRODUCTS

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ABOUT NASA
HUBBLE TECHNOLOGY SUMMARY
SPACECRAFT SYSTEM
HUBBLE OPTICS
Pointing Control System
SCIENCE INSTRUMENTS
HUBBLE'S OPTICS
Optical Assembly
Hubble's optical telescope assembly consists of two mirrors, support trusses, and the focal plane structure. This system is a Ritchey-Chretien design in which two aspheric mirrors serve to form focused images over the largest possible field of view.
ROLLOVER  text (below left) to view light path segment on graphic (below right)

Light enters Hubble's aperture
and travels down the main baffle. A
baffle is a surface which eliminates
stray light.

Light is reflected by the primary
mirror
which measures about 8
feet (2.4 meters) in diameter.
Because of the concave shape, the
primary mirror converges the light
to the secondary mirror through a
secondary baffle.

The secondary mirror, measuring
about 1 foot (0.3 m) in diameter
receives the light. It in turn reflects
the still-converging light back
toward the primary mirror through
a central baffle.

The light travels through a hole in
the primary mirror, to reach the
focal plane, where the science
instruments examine the light.