WEBVTT FILE

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!!musiC@!!!musiC@!

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!!musiC@!!!musiC@!

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!!musiC@!!!musiC@!

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!!musiC@!!!musiC@!

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!!musiC@!!!musiC@!

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!!musiC@!!!musiC@!

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-In 1923, Hermann Oberth,
a German scientist,

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in a book entitled

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"The Rocket into
Interplanetary Space,"

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put forward a dream --

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if we could look at the heavens

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with an astronomical
telescope in orbit,

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unhindered by the shielding
sea of atmosphere

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that blankets the Earth,

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think of the discoveries
we would make,

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the clear vision of the universe
we would have in quiet space.

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!!musiC@!!!musiC@!

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!!musiC@!!!musiC@!

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!!musiC@!!!musiC@!

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!!musiC@!!!musiC@!

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The telescope -- an instrument
for collecting more light

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than would normally
enter the human eye.

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For over 300 years, light,
optics and the human imagination

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have sculptured our
perception of the universe.

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Today, large telescopes such
as those at Palomar Mountain

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and Kitt Peak

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carry out detailed
investigations

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of very faint objects

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at the limits of perception.

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The naked eye has been
replaced by spectroscopes,

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photographic plates, computers,

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yet a fundamental challenge,

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a link between past and present,
remains ever constant.

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The quest for more light --

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to see fainter
and more distant objects,

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to construct better
light collectors.

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-This is a photograph
of the galaxy in Messier 33,

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a nearby galaxy,
a rather common type,

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and quite illustrative
of the type of image

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that we obtain with telescopes

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that are based on
the surface of the Earth.

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This type of information,

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together with spectra

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like the plate
that I'm holding here,

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form the largest part
of the information obtained

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and used by
ground-based astronomers.

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It's quite good, but nowhere
as good as it might be.

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Astronomers themselves and many
in the lay public

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don't appreciate at times
the enormous distances

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that they're dealing with.

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When we look at the photograph
of a cluster of galaxies

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like this,

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it's hard to appreciate
that these images

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that we obtain now
are from galaxies

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that are probably
a billion light-years away.

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With space telescope,

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we'll be able to look
to much greater distances

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and therefore much
further back into time,

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in fact, much closer to the
creation of the universe itself.

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In order to understand how
the Space Telescope works,

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we really need to understand
how the astronomer

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and the astrophysicist
work with light.

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-Almost all the information
we have about the universe

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reaches us in the form
of electromagnetic radiation,

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which objects either radiate,
absorb or reflect.

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The spectrum disperses
this radiation

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into its separate colors --

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visible light,
infrared radiation,

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radio waves at one end to x-rays
and gamma rays at the other.

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Now, each element in nature

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has a characteristic
spectral signature,

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a fingerprint of light,
if you will.

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Because common Earthly
elements have been found

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in the Sun and stars,

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we can determine through
a star's own unique

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stellar spectrum
the speed of an object,

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its temperature, density,
chemical composition.

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Each band of light becomes
a window into the universe

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with a unique view.

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!!musiC@!!!musiC@!

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But many wavelengths are
permanently inaccessible

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to astronomers
using earthbound telescopes

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due to the Earth's atmosphere

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which, enshielding us

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from most of the biologically
harmful radiations,

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allows only visible light and
varying amounts of ultraviolet,

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infrared and radio
to reach the ground.

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We are given a very incomplete
picture of the universe

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in these wavelengths.

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Our stellar fingerprint
is difficult to analyze.

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The atmosphere also frustrates
ground-based

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optical observations.

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100 miles deep. it is
filled with dust particles,

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water vapor and other
obscuring materials.

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Constantly shifting layers
of air of different densities

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bend light back and forth.

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Atmospheric turbulence imposes
a fundamental limitation

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on the telescope's ability

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to see clearly two objects
close together in the sky.

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At times of bad seeing,

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stellar images waver like candle
flames in a gentle breeze.

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The Space Telescope

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will be out where the images
are completely quiet,

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where the full spatial
and wavelength resolution

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powers of the telescope
can be used.

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It will peer far into
the ultraviolet

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and infrared regions
of the spectrum.

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A galaxy, seen through
the Earth's atmosphere

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as a big, shimmering
fuzz ball in space,

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will be brought
into sharp, clear

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and steady view
for study and analysis.

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We will see it 10 times
clearer than we see it now.

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We will see 50 times
further into the universe

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than the best ground-based
telescopes can see --

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all this from a telescope
no different in principal

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than the reflecting telescope
of Newton and his descendants.

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-Every optical telescope

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operates in essentially
the same manner.

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It gathers a part of the light
produced by or reflected

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from an object,

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concentrates this light
in a single area,

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the focal plane,

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and then magnifies
the image formed there.

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!!musiC@!!!musiC@!

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-So in space, as on Earth,
we must begin with a mirror,

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in this case,
polished to within one

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half a millionth
of an inch in accuracy.

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As light enters from space,

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something must catch
the reflection

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of our primary mirror.

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A secondary mirror
is set into place.

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An image must now be fed
into a variety

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of auxiliary instruments,

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so we provide a package of five
major scientific instruments

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which will convert telescope
images into useful data.

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The scientific instruments
and optical assembly

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must then be encased
in a shell,

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which protects them from dangers
in the space environment

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such as stray light
or micrometeoroids.

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To power our telescope,
we tune to the sun for energy

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and attach solar array panels.

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In the Earth's shadow,

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we will power
our telescope by batteries.

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Finally, we must have a means
of communicating

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with our telescope,

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so we obtain
two high-gain antennas.

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Data which these antennas
beam back to Earth

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will be converted to pictures.

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!!musiC@!!!musiC@!

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-200-inch telescope here
at Mount Palomar in California

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is only about twice as big
as the Space Telescope will be,

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yet it's very much more massive

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because of course it has to work
in the Earth's gravity.

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Our own telescopes,

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including this one
and the Space Telescope,

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are essentially the same.

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They gather light so that
we can analyze it

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with various instruments.

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The Space Telescope will have
five such instruments.

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There will be two
wide-field cameras,

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which take pictures of the sky,
one over a wide region

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and another over
a smaller region.

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The smaller-region camera
will have much higher resolution

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than the other.

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There will also be
two spectrographs

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aboard the Space Telescope.

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One will be used on
fairly bright objects

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and take the
highest-resolution spectra.

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The other will be used
for quite faint objects

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such as galaxies and
far-away quasi-stellar sources.

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There will also be on the
Space Telescope an instrument

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that utilizes the fine guidance
system of the telescope.

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This is the system that
keeps the telescope

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pointed quite accurately
at the stars during an exposure.

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This instrument will allow us
to measure the distance

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between stars quite
accurately on the sky

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and also their motions
over a short period of time.

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-The Space Telescope,
due to be launched in the 1980s,

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will be hoisted into orbit
some 500 miles above the Earth

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by the space shuttle.

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Fitting into the shuttle's
cargo bay,

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the telescope will be latched
to a tilting mechanism

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and rotated into a 90-degree
position for checkout.

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It will then be placed
in a vertical angle,

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released and its power and
communication systems deployed.

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The periodic revisit
of the shuttle will allow

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for the replacement
of components

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and routine maintenance.

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Every 5 years, the telescope
will be returned to Earth

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for major ground refurbishment.

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This ability to service the
telescope through human care

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will extend its life-span
up to 20 years.

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-It will orbit above
our murky atmosphere

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and obtain images of objects

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that are incredible
distances away,

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perhaps a galaxy's 14 billion
light-years' distance,

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so far away that when the light
first set out towards us,

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there was no Earth,
no Sun, no Milky Way Galaxy.

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We will be probing the time
of the earliest history

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of the universe.

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The Space Telescope is,
in a way,

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a little like Galileo's
first telescope.

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Wherever
Galileo pointed his telescope,

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he made major new discoveries.

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Look at the moon.
You find mountains and craters.

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Look at Saturn.
You find rings.

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Look at the Milky Way.

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You find it is littered
and composed of stars.

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Every one of these discoveries,

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things that people
had not known before.

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I think it's going to be
very similar

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with the Space Telescope.

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It will illuminate celestial
objects that we know about.

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It will discover celestial
objects never before guessed.

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It will provide insights into
the most important questions

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such as stellar evolution,

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such as the search for planets
going in and out of the stars

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and the grandest cosmological
questions of the origin,

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nature and fate of the universe.

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The Space Telescope is a kind of
grand intellectual adventure

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for all of us,

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which will cast light
not just on the cosmos

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but also on ourselves.

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-It's impossible to predict
what Space Telescope will bring

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in terms of its results,

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but we do know the results
will be exciting.

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When the first radio
telescopes were built,

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we did not know that we would
find quasars and pulsars,

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or when the first x-ray
telescopes were built,

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we did not know that
we would discover x-ray stars.

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With Space Telescope,
we will find many new things.

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We'll find exciting things.

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-Stretching the mind of
humankind to the very beginning

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and end of space and time,

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the Space Telescope may tell us

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at last whether the universe
will expand forever

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or whether that
expansion is slowing.

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!!musiC@!!!musiC@!

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!!musiC@!!!musiC@!

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It may help us learn more
about the violent events

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of the universe --

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pulsars...

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quasars...

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the gravitational implosions

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that produce black holes.

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!!musiC@!!!musiC@!

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It may also tell us
how the universe began

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and how it will end.

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But ultimately, as is the case
with all voyages of discovery,

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its greatest contribution will
be the unexpected breakthrough

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that brings completely
new knowledge.