HUBBLE SPACE TELESCOPE

Donald Savage
Headquarters, Washington, DC              April 24, 1995
(Phone:  202/358-1547)

Tammy Jones
Goddard Space Flight Center, Greenbelt, MD
(Phone:  301/286-5566)

Ray Villard
Space Telescope Science Institute, Baltimore, MD
(Phone:  410/338-4514)


RELEASE:  95-56


FIFTH ANNIVERSARY OF HUBBLE LAUNCH OBSERVED TODAY

       Today is the fifth anniversary of the launch of 
NASA's Hubble Space Telescope.  Celebrated throughout the 
world as the finest astronomical instrument ever built, 
Hubble has provided remarkable new views of the universe 
which have revolutionized astronomers' thinking about a 
variety of current astronomical mysteries.  

       "The Hubble Space Telescope is truly a national 
scientific treasure," said Dr. Wesley Huntress, Jr., NASA's 
Associate Administrator for Space Science.  "With a rate of 
discovery that is unprecedented for any modern observatory, 
Hubble not only has revolutionized astronomy, it has 
engaged the interest and imagination of the public more 
than any space science satellite has done before.

       "And that may be its most far-reaching and important 
legacy -- getting a new generation of young people excited 
about science," Huntress said.

Launch and First Three Years

       Launched April 24, 1990, on the Space Shuttle 
Discovery's STS-31 mission, the Hubble Space Telescope, 
with a resolving power calculated to be ten times better 
than any telescope on Earth, was poised to open a new era 
in astronomy.  Within a few months, however, a flaw was 
discovered in Hubble's main mirror which significantly 
reduced the telescope's ability to focus.

       The focusing defect was due to spherical aberration, 
an optical distortion caused by an incorrectly shaped 
mirror.  Instead of being focused into a sharp point, light 
collected by the mirror was spread over a larger area in a 
fuzzy halo.  Images of objects such as stars, planets and 
galaxies were blurred.  However, on relatively bright 
objects, Hubble's cameras were still able to provide images 
far superior to any telescope on the ground.  

       Program and project management officials, working 
with the scientific community, developed a plan to take 
advantage of the telescope's instruments that were not 
affected by the aberration, such as ultraviolet and 
spectrographic observations.

       During its first three years of operation, Hubble 
provided significant new information and discoveries about 
the universe, including astonishing images of supernova 
1987A and a disk of cold gas fueling a black hole.

       The team also began developing a corrective optics 
package that, together with a new camera already scheduled 
for installation in Hubble in 1993, would restore Hubble to 
its intended imaging capabilities.  

       The two major instruments planned for installation, 
the Wide Field/Planetary Camera (WF/PC-II) and the 
Corrective Optics Space Telescope Axial Replacement 
(COSTAR), were designed to correct the aberration.  WF/PC-
II was designed so that the light reaching each of the 
instrument's four cameras was corrected by relay mirrors 
polished to a prescription compensating for the incorrect 
figure produced by Hubble's primary mirror.  

       COSTAR routed properly focused light to three of 
Hubble's five instruments.  Ball Corp. built Hubble's 
corrective optics for the Goddard Space Flight Center, 
Greenbelt, MD.

       The seven astronauts selected to service Hubble 
practiced for nearly a year-and-a-half.  They spent 
hundreds of hours practicing and learning the uses of more 
than 100 different servicing tools.  This mission would be 
one of the most challenging missions NASA had ever 
attempted.  

Servicing Mission Opens New Era

       On December 2, 1993, the STS-61 crew launched on 
Space Shuttle Endeavour for an 11-day mission with a record 
five spacewalks planned.  Watched by millions worldwide on 
live television, the astronauts endured long hours of 
challenging spacewalks to install instruments containing 
the corrective optics and replaced the telescope's solar 
arrays, gyroscopes, and other electronic components.  

       They installed WF/PC-II and replaced the High Speed 
Photometer with the COSTAR instrument.  They also installed 
a new computer co-processor to upgrade the telescope's 
computer memory and processing speed, the Solar Array Drive 
Electronics unit and the Goddard High Resolution 
Spectrograph Redundancy Kit.  

       The crew completed everything it set out to do and 
the mission was declared a success.  After five weeks of 
engineering check-out, optical alignment and instrument 
calibration, the confirmation of success came as the first 
images were received on the ground from the space 
telescope.  

     NASA Administrator Daniel Goldin was joined in 
announcing the successes by Dr. John Gibbons, Assistant to 
the President for Science and Technology, and Sen. Barbara 
Mikulski (D-MD), at a press conference at Goddard.  

       "This is phase two of a fabulous, two-part success 
story," Goldin said at the press conference.  "The world 
watched in wonder last month as the astronauts performed an 
unprecedented and incredibly smooth series of space walks.  
Now, we see the real fruits of their work and that of the 
entire NASA team."

       Not only has Hubble advanced science's understanding 
of the universe, it also is making direct contributions 
through a variety of technological spinoffs.  During 1994 a 
new, non-surgical breast biopsy technique was developed 
using imaging Charge Coupled Devices, originally developed 
for Hubble's Imaging Spectrograph.  This technology now 
enables doctors to precisely locate a suspicious lump in a 
woman's breast and use a needle, instead of a scalpel, to 
extract a sample of tissue for study. 

Looking Ahead

       The Hubble Space Telescope was designed to work on 
orbit for 15 years, providing an unparalleled observatory 
for astronomers well into the next century.  To keep Hubble 
running smoothly, three additional servicing missions are 
planned, similar to but probably not as extensive as the 
first servicing mission in 1993.

       During the next servicing mission, scheduled for 
February 1997, astronauts will install two new instruments 
-- the Space Telescope Imaging Spectrograph and the Near 
Infrared Camera and Multi-Object Spectrograph.  The third 
servicing mission, scheduled for November 1999, will see 
the installation of the Hubble Advanced Camera for 
Exploration, which will greatly enhance the telescope's 
imaging capabilities.

Hubble's Ten Most Important Scientific Discoveries 

       Hubble program and project scientists selected the 
following "top ten" list of discoveries from hundreds of 
findings made over the past five years by scientists using 
Hubble.  The selections were based on their scientific 
merit and long-term importance in advancing the field of 
astronomy.  Since it became operational in 1990, NASA's 
Hubble Space Telescope:

  *  Offered the first conclusive evidence for the 
existence of immense black holes, millions or billions of 
times the mass of Earth's Sun. 

  *  Showed that the universe might be much younger than 
had been previously thought.  This was accomplished by 
calculating the universe's expansion rate based on an 
accurate Hubble distance measurement to a remote galaxy.

  *  Gave the first direct visual evidence that the 
universe is evolving as predicted in Big Bang cosmology, by 
resolving the shapes of the farthest galaxies ever seen. 

  *  Discovered that quasars, very distant and remarkably 
bright objects, are even more mysterious than commonly 
thought because many do not dwell in the cores of galaxies, 
but are isolated in space.

  *  Suggested that dark matter in the universe is more 
exotic than previously thought, by finding that nature 
doesn't make enough of the extremely small Red Dwarf stars 
that were once a leading candidate for the universe's 
"missing mass."

  *  Supported the Big Bang theory by refining estimates of 
the amount of deuterium in space, an element created in the 
initial cosmic fireball that gave birth to the universe.

  *  Solved the mystery of intergalactic clouds of hydrogen 
by showing that they are really gigantic halos of galaxies.

  *  Implied that planets, and presumably life, might be 
abundant in the universe by discovering disks of dust that 
might be embryonic planetary systems around young stars. 

  *  Provided important details and surprising findings of 
the spectacular collisions of comet Shoemaker-Levy 9 with 
Jupiter last year.  

  *  Revealed dynamic weather changes on nearly all the 
planets with a clarity once attainable only with spacecraft 
flybys.  Scientists found that most planets' atmospheres 
are much more active than previously believed, and the 
ability of Hubble to 'revisit' the planets allows frequent 
monitoring similar to Earth weather satellites.

A Photo Gallery Of The Universe:  The Best Of 
Hubble Images 1990-1995

       Hubble Space Telescope's dramatic images evoke a 
sense of awe and wonder.  The following is a selection of 
Hubble's ten most spectacular and important images, 
selected on the basis of scientific value as well as 
aesthetic content.

       The images are available in color or B&W prints or 
via the Internet in a special Hubble 5th Anniversary Home 
Page.  See Editor's Note following this release for 
information on obtaining images or accessing the home page.  

SUPERNOVA 1987A - HALO FOR A VANISHED STAR
       An eerie, nearly mirror-image pair of red 
luminescent gas "hula-hoops" framing the expanding debris 
of a star was seen as a supernova explosion in 1987.  April 
1994.
NASA photo number:   94-HC-39

THE ORION NEBULA - STELLAR BIRTHPLACE
       An immense wall of glowing gases forms a colorful 
backdrop to dozens of newborn stars, many of which have 
dust disks -- as revealed by Hubble -- that might be 
embryonic solar systems.  January 1994.
NASA photo number:   94-HC-163

THE RING GALAXY - RESULT OF A BULL'S-EYE COLLISION
       A spectacular head-on collision between a spiral 
galaxy and a smaller intruder sends out a ripple of energy 
that triggers a firestorm of new star birth, forms a 
dazzling ring-like structure.  January 1995.
NASA photo number:  95-HC-23 

COMET P/SHOEMAKER-LEVY 9 BOMBARDS JUPITER
       Hubble followed unexpected and dramatic changes in 
Jupiter's atmosphere caused by collisions with comet 
fragments.  The titanic blasts left Jupiter with a 
temporary "bruised" appearance, caused by black debris that 
was tossed high above the giant planet's cloud tops.  July 
1994.
NASA photo number:  94-HC-188

SPIRAL GALAXY M100
       A majestic pinwheel formed by hundreds of billions 
of stars harbors rare pulsating stars that can yield clues 
to the size and age of the universe.  The galaxy is so far 
away, Hubble sees it as it appeared at about the time 
dinosaurs roamed the Earth.  January 1994.
NASA photo number:  94-HC-280

SATURN STORM
       A rare storm, large enough to swallow Earth, appears 
near Saturn's equator.  High altitude winds give the storm 
a distinctive arrowhead shape. 
January 1994.
NASA photo number:  94-HC-556

RING AROUND A SUSPECTED BLACK HOLE IN GALAXY NGC 
4261
       The gravitational pull of a suspected super-massive 
black hole forms a Frisbee-like disk of cool gas, at the 
core of an energetic galaxy.  Subsequent Hubble 
observations of yet another active galaxy confirmed the 
reality of monstrous black holes -- gravitational "sink 
holes" that trap everything, even light.  November 1992. 
NASA photo number:  92-HC-708

PLANETARY NEBULA NGC 6543, GASEOUS COCOON AROUND A 
DYING STAR
       Mysterious stellar fireworks create expanding gas 
shells and blowtorch-like jets which form a spectacularly 
intricate and symmetrical structure.  The nebula is a 
fossil record of the late stages of the star's evolution.  
January 1995.
NASA photo number:  95-HC-24

CYGNUS LOOP - BLAST WAVE FROM A STELLAR TIME-BOMB
       High speed gas from a supernova explosion slams into 
dark cooler clouds of interstellar material.  Shocked and 
heated by this tidal wave of energy, the clouds glow in 
bright, neon-like colors.  February 1995.
NASA photo number:  95-HC-77

WEATHER FORECAST FOR MARS 
       Wispy clouds, a melting polar ice cap, and a dust-
storm free surface all indicate a cool, clear spring time 
in the Martian northern hemisphere.  Hubble also is serving 
as a weather satellite for studying the climate on other 
planets.  February 1995.
NASA photo number:  95-HC-115

       The Space Telescope Science Institute is operated by 
AURA (the Association of Universities for Research in 
Astronomy, Inc.) for NASA, under contract with the Goddard 
Space Flight Center, Greenbelt, MD.  The Hubble Space 
Telescope is a project of international cooperation between 
NASA and the European Space Agency.

   - end -

EDITOR'S NOTE:   The HST Top Ten Images are available to 
news media representatives by calling the Headquarters 
Broadcast & Imaging Branch at 202/358-1900, the Goddard 
Space Flight Center at 301/286-8956 or 286-7277, or the 
Space Telescope Science Institute at 410/338-4562 (use the 
NASA photo number listed for each image).  


       The "Top Ten Images" also are available via the 
Internet in a special Hubble 5th Anniversary Home Page in 
GIF, JPEG and TIFF formats.  Users can access this page 
using the following protocol:

  *  Anonymous ftp to ftp.stsci.edu:

GIF files are in /pubinfo/gif, with extension ".gif"
JPEG files are in /pubinfo/jpeg, with extension ".jpg"
TIFF files are in /pubinfo/tiff, with extension ".tif"

  *  WWW -- follow links in http://www.stsci.edu/pubinfo/BestOfHST95.html

 or browse directories using 

http://www.stsci.edu/ftp/pubinfo and links to gif, jpeg and tiff

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