It's the last round-up for the people's telescope. Next August, after 20 years of hype, disappointment, blunders, triumphs and peerless glittering vistas of space and time, and four years after NASA decided to leave the Hubble Space Telescope to die in orbit, setting off public and congressional outrage, a group of astronauts will ride to the telescope aboard the space shuttle Atlantis with wrenches in hand.

That, at least, is the plan.
“It's been a roller-coaster ride from hell,” Preston Burch, the space telescope's project manager, said in his office at the Goddard Space Flight Center of the controversy and uncertainty.

In a nearby building, the Hubble's astronaut knights - dressed as if for surgery, in white gowns, hoods and masks - swarmed through a giant clean room to kick the tyres, so to speak, of new instruments destined for the Hubble and to try out techniques and tools under the watchful eye of the Goddard engineers.

They practiced sliding a new wide-field camera, suspended in air like a magician's grand piano, in and out of its slot on a replica of the telescope that is mechanically and electrically exact down to the tape around the doors. “We have to train their minds and bodies,” said Michael Weiss, the deputy project manager of Hubble, adding that when the astronauts see the real telescope in orbit, “they say they've seen it before.”

Spacewalking astronauts have refurbished the Hubble four times in the last two decades. But the trip planned for August, almost everybody agrees, really will be the last service call. The shuttles are scheduled to stop flying in 2010, and without periodic maintenance, the telescope's gyroscopes and batteries are expected to die within about five years.

Astronauts, engineers and scientists here say they are resolved to pull off the most spectacular rejuvenation of the telescope yet, one, they say, that will leave it operating at the apex of its abilities well into the next decade.
“It will be a brand new telescope, practically,” said Matt Mountain, the director of the Space Telescope Science Institute on the Johns Hopkins campus in Baltimore. He added, "We want to return crackerjack science we can be proud of."

The coming visit, Mountain said, is unique. "You don't have to do routine maintenance," he said. "It's like a car you're only going to keep another 20,000 miles. You don't buy new tyres."
Engineers and project managers are busy mapping out five days of spacewalks.

If all goes well, the astronauts will install a new camera and spectrograph and change out all the gyroscopes that keep the Hubble properly pointed and the batteries that keep it running.

They are also planning to repair a broken spectrograph and the Hubble's workhorse, the Advanced Camera for Surveys, which had a severe short-circuit last winter and was pronounced at the time probably beyond repair.
Drastic turnabouts have characterised the Hubble telescope, hailed before its launching in April 1990 as the greatest advance in astronomy since Galileo invented the telescope.

In space, the Hubble would be able to discern details blurred by the turbulent murky atmosphere. But its 94-inch-diameter mirror turned out to have been polished to the wrong shape, leaving it with what astronomers call, a spherical aberration. The Hubble became branded as a "technoturkey."

In 1993, astronauts fitted the telescope with corrective lenses, and the cosmos snapped into razorlike focus.
Three more visits by astronauts kept the Hubble running and, by replacing old instruments, actually made it more powerful.

Along the way, the astronauts graduated from yanking equipment fitted with large astronaut-friendly handles to operating on instruments never meant to be repaired by people wearing the equivalent of boxing gloves in space.

In 2002, after an infrared camera unexpectedly ran out of coolant, the astronauts attached a mechanical refrigerator to run coolant through its pipes. A year later, the Hubble's astronomers used the rejuvenated camera along with the advanced survey camera to record the deepest telescopic views ever obtained of the universe. The images captured galaxies as they existed a few hundred million years after the beginning of time.

“When you have an instrument that reaches so far beyond what you've ever had before, you make discoveries that nobody ever thought of before," said John Grunsfeld, who will be the payload commander on the Atlantis mission. "And we see things that nobody ever saw before. As a result, you know, Hubble became not just an observatory, but an icon for all of science. And Hubble has become part of our culture." That status did not come cheaply.

Edward Weiler, the director of the Goddard center and formerly the associate administrator for science at NASA, estimated that over the years the Hubble had cost $9 billion. "There are few people, especially Americans, who won't say it was worth it," he said.

All this seemed doomed to a premature end after the shuttle Columbia disaster in 2003 that killed its crew of seven. Sean O'Keefe, who was then the NASA administrator, declared that a shuttle flight to the telescope was too risky because, unlike the space station, it offered no safe haven if anything went wrong with the shuttle. The public was appalled. Schoolchildren even offered to send their pennies to NASA to keep the telescope going.

Some astronomers and engineers challenged the reasoning of O'Keefe, whose background was in public administration, not engineering. Others in the space science community, noting that the science budget was being squeezed by President Bush's Moon-Mars initiative, suggested that it was time to move on and that the Hubble repair money might be better spent on other science projects.

In February 2005, however, O'Keefe resigned to become the chancellor at Louisiana State University. His successor, Michael Griffin, who has a doctorate in aerospace engineering, instituted a rigorous risk analysis, culminating in a two-day meeting of experts that concluded it was no riskier to fly to the telescope than to go to the space station. In fall 2006, after the shuttles had begun flying again, Griffin approved the Hubble mission to a standing ovation from scientists and engineers.

"We all agree the risks are acceptable," Leckrone said. "Griffin led us through that process with a good deal of intellectual vigor. He didn't fake it."

Asked whether the astronomers were tempted to run the rejuvenated instrument frugally to prolong its life beyond its anticipated 2013 demise, Mountain said the idea was to go for broke.
"We don't want to trade science for false longevity," he said.


Dennis Overbye
New York Times