ROANOKE TIMES
Copyright (c) 1997, Roanoke Times
DATE: Sunday, February 9, 1997 TAG: 9702100118
SECTION: NATIONAL/INTERNATIONAL PAGE: A-3 EDITION: METRO
DATELINE: HOUSTON
SOURCE: Houston Chronicle
Whether it's exposing a mind-boggling conflict over the age of the universe or gathering compelling evidence of black holes, the Hubble Space Telescope has come light years from the days when critics dismissed it as a cosmic boondoggle.
``The Hubble is turning my generation's science fiction into today's reality,'' said the National Aeronautics and Space Administration's Ed Weiler, the telescope's chief astronomer. ``Not only is it delivering answers to long-standing questions, it is also starting to shake some of our most cherished beliefs.''
This week, spacewalking shuttle astronauts plan a $795 million make-over that will begin a new chapter in the Hubble saga.
Once refurbished, the $3.8 billion telescope should enable astronomers to probe deeper into the universe than ever before, perhaps revealing the processes by which galaxies form and pinning down the age of the cosmos with new precision.
It will be the first human encounter with the Hubble since a December 1993 shuttle mission. Astronauts then conducted five spacewalks to correct the infamous optical flaw that escaped NASA's detection before the observatory was launched seven years ago.
That difficult mission proved a watershed, transforming the telescope from an object of ridicule to one that inspires awe in scientific circles. All told, the Hubble has been trained on more than 10,000 objects, from Mars to energetic quasars.
Its findings have dramatically challenged physical theory. The imagery reveals a universe rife with billions more galaxies than previously believed, pillars of energetic gases condensing into new stars and mighty pinwheel-shaped star systems in the midst of cataclysmic collision.
Some observations have raised profound questions for astronomers.
For instance, some of the oldest stars in the heavens, believed to be 15 billion to 20 billion years old by classic methods of measurement, now appear to be much older than the universe itself. As implausible as finding a daughter older than her mother, that circumstance threatens to undermine decades of theoretical work on how objects interact to shape the cosmos.
Using the Hubble's powers to view distant objects, astronomers believe they can accurately gauge the age and size of the universe.
``The numbers are coming out pretty consistently in the 9 to 12 billion range,'' Weiler said of the universe's age. ``That really gives us a problem.''
The new observations point to the possibility that either estimates of the early mass of the universe are inaccurate or longer-held tenets of stellar evolution are in error.
In other arenas, the Hubble has peered into the fast-moving whirlpool of gas and dust swirling at the heart of a galaxy 100 million light years away. Measurements of the velocity suggest the presence of a behemoth at the core with a mass 1.2 billion times that of the sun.
The observations fit the classic definition of a black hole, a theoretical concept until the Hubble observations.
Efforts are also under way to detect black holes at the heart of quasars, distant objects that radiate incredible amounts of light for their compact size.
However, that and other advances are limited by the current optical capability of the space telescope. Experts envisioned such obstacles and designed Hubble so that shuttle astronauts could make ``servicing missions'' every three years.
The first service flight - the 1993 mission - turned into a do-or-die repair effort after NASA ground controllers were unable to properly focus the telescope after its April 1990 launch. The difficulty was traced to the Hubble's 94-inch-wide primary mirror, the optical device that collects and focuses the starlight fed into the telescope's collection of cameras.
The fuzzy focus was corrected by spacewalking astronauts who installed a pair of large new components equipped with small corrective lenses.
The second service mission is scheduled to begin Tuesday with the shuttle Discovery aiming for liftoff from the Kennedy Space Center in Florida at 3:56 a.m..
The crew plans to rendezvous with Hubble early Thursday and do four six-hour spacewalks to work on the observatory.
The astronauts plan to remove a pair of telephone booth-sized instruments that analyze the ultraviolet radiance that stars emit.
A widely held theory suggests that the universe was once condensed infinitesimally before it burst explosively in an event known as the Big Bang. Astronomical observations reveal an expansion still under way, with the most distant regions of the universe accelerating away at the greatest velocity.
With an infrared instrument, astronomers expect to extend their current vision with the Hubble from a time when the universe was one-third its current age to a time when it was one-tenth.
What scientists hope to see are the building blocks of galaxies that now exist. Theories that galaxies formed from clouds of gas and dust condensing after a Big Bang are giving way to ideas that they grew from smaller clusters of stars that collided.
``Will there be any objects there?'' pondered Rodger Thompson, a University of Arizona astronomer who will lead the observations. ``The fact we can detect something doesn't necessarily mean there is anything there.''
LENGTH: Medium: 98 linesby CNB