A vast improvement

Hubble's eyesight is 20-20 - NASA says repair of optical problem is a glorious success

Showing off crisp new images of distant galaxies as proof, NASA on Thursday declared its dramatic December mission to correct the Hubble Space Telescope's optical flaw a success.

"From our perspective the Hubble Space Telescope is fixed, and it's fixed beyond our wildest expectations," said Ed Weiler, NASA's chief Hubble astronomer. "It's fixed on time and on budget."

Key White House and congressional officials and NASA Administrator Dan Goldin joined Weiler for the announcement, expressing hope the achievement will translate into crucial political and public support for ambitious new endeavors, including the assembly of an international space station later this decade.

"If anything, this underscores the support the administration gives to this kind of can-do scientific and technological leadership," said John Gibbons, President Clinton's science adviser.

"There is now a new confidence that the space station can be built," said U.S. Sen. Barbara Mikulski, D-Md., who chairs NASA's Senate appropriations subcommittee.

"It will take extraordinary resources, and we therefore have to know truly what we are getting into," Mikulski said. "But there will be technical competency and astronaut capability to do that."

Officials gathered at NASA's Goddard Space Flight Center in Greenbelt, Md., the telescope's control center outside Washington, to publicly reveal the first images. The American Astronomical Society has scheduled more releases today.

Elated, space telescope astronomers said Thursday the achievement will enable them to begin a two- to three-year effort to accurately calculate the age of the universe, which they currently estimate began with a tremendous explosion 10 billion to 20 billion years ago.

The rehabilitated observatory will also enable astronomers to search for tangible evidence of planets circling nearby stars and proof that mysterious black holes actually exist, a task that is scheduled to begin this spring.

Those are among the ambitious objectives that disappointed teams of astronomers were forced to postpone following the April 1990 launch of the $1.6 billion space telescope. Within weeks of the launch, the space agency discovered the observatory's 94-inch-wide primary mirror had been manufactured a decade earlier with a small but significant flaw that blurred images and kept them from studying faint, distant phenomena.

Reacting quickly to mounting criticism from lawmakers, the public and influential science groups, NASA promised repairs within four years.

A team of seven astronauts blasted off aboard the shuttle Endeavour on the complex $700 million, 11-day repair mission on Dec. 2. Following a flawless rendezvous at an altitude of nearly 370 miles, the fliers grappled the 13-ton observatory with the shuttle's robot arm and positioned it atop a workbench in the cargo bay.

Spacewalkers Story Musgrave, Jeff Hoffman, Tom Akers and Kathy Thornton then began an unprecedented series of five spacewalks in which they installed two large optical devices -- a new Wide Field/Planetary Camera and an assembly called the Corrective Optics Space Telescope Axial Replacement, or COSTAR.

Both components had been equipped with a collection of tiny, precisely ground mirrors that could be positioned inside the telescope in response to commands from ground controllers to remove the blur in the imagery caused by the flawed mirror.

Additionally, the astronauts replaced the telescope's solar arrays, which caused the telescope to wobble periodically because of a design flaw, installed new gyroscopes and other enhancements to its intricate pointing system and augmented the power of the observatory's flight computer.

On Thursday, Weiler and his colleagues displayed images comparing the capabilities of the Hubble's two major cameras before and after the repair mission. The performance of the Wide Field/Planetary Camera, which has its own set of corrective optics, and the Faint Object Camera, which relies on the new COSTAR optics for its correction, was sharply improved.

"There is only one way to describe these images, and that is absolutely incredible," said Jim Crocker, who coordinated the development of the COSTAR.

So powerful is the telescope's new optical prowess that if positioned in Washington, D.C., it could spot a firefly 8,500 miles away in Tokyo. If the glow was actually two insects, they would be recognized as a pair rather than a single source of light as soon as they separated by 10 feet.

For the 1,200 to 1,500 astronomers who plan to use the most powerful optical telescope ever placed above the grime and distorting influences of the Earth's atmosphere, that kind of resolving power is significant.

The world's best ground-based observatories can see objects 12 billion to 13 billion light years away, but they appear very fuzzy. Objects one to two billion light years away can be resolved with clarity.

Prior to its repair, the Hubble's Wide Field/Planetary Camera furnished clarity to objects three to four billion light years distant.

With the repairs, the space telescope is powerful enough to peer into a realm 10 billion to 12 billion light years away. At those vast distances, the observatory is functioning as a time machine, receiving light emitted by the earliest objects that formed in the early universe.

Officials said they had their first hint of the mission's success on Dec. 18, five days after the Endeavour astronauts landed, as they witnessed the transmission of the first unfocused images of the rehabilitated Hubble to ground controllers.

With difficulty, they contained their enthusiasm while astronomers and engineers raced through a focusing period they originally believed would require six to eight weeks.

Goldin on Thursday expressed only a slight reservation on behalf of ground-control teams who will spend several more weeks evaluating all of the nearly one dozen telescope repairs by the shuttle crew.