Adjusting Man’s Eyes on Heavens : Astronomy: The Hubble Telescope will improve scientists’ view of space from 20/200 to 20/20.
Charles F. Bolden, 43, who served as a combat pilot with the Marine Corps in Vietnam, knows exactly what he will be doing as the world’s most pampered piece of hardware is lifted slowly out of the shuttle Discovery’s payload bay this week.
“I will just sit there and hold my breath,” says a man who flew more than 100 missions over Vietnam, Laos and Cambodia in the early 1970s.
As the Discovery’s pilot, Bolden’s main job will be to look over everybody else’s shoulder--”choreographing,” as he puts it, the delivery to space of the most sophisticated and most expensive satellite ever built, a jewel of a telescope that was created out of the desire to probe the deepest secrets of the universe.
The Discovery is scheduled to lift off at 5:47 a.m. Tuesday (PDT), and the telescope is to be deployed about 23 hours later.
The $2-billion-plus instrument, named for Edwin P. Hubble, the astronomer who, in the 1920s, discovered that the universe is expanding, is destined to forever change “humankind’s perception of itself and its place in the universe,” said Lennard Fisk, chief scientist for the National Aeronautics and Space Administration.
That’s a tall order, but “The Hubble,” as it is called, is no ordinary piece of equipment. The satellite is a nearly perfect testament to engineering excellence and a window onto worlds never seen before.
And it’s not just for the scientists.
“Everybody who has ever looked up at the nighttime sky and seen a star or a planet can relate to this thing,” observed Bolden.
“The Hubble is a half billion times more sensitive than the human eye,” Fisk said.
Free of atmospheric interference, it will see objects billions of light years away with up to 10 times the sharpness of ground-based telescopes.
“It’s as though we currently have 20 over 200 vision and we are about to be given a pair of glasses that brings the universe to 20/20 clarity,” Fisk explained.
The Hubble, years behind schedule, has already been assigned a long list of astronomical targets, but most experts predict that the orbiting telescope will turn up a few surprises.
“You can be sure that what we anticipate today will not be the fundamental discoveries of Hubble,” Fisk said. “Nature is much more imaginative, and very much more clever than we are, and it is bound to amaze us.”
But before all that happens, the Hubble must first be delivered to space 380 miles above the Earth, and that’s no simple task.
The entire mission, for example, would be jeopardized if the Discovery failed to reach that record high orbit. But beyond that, the deployment of the 25,000-pound telescope is an extremely delicate operation fraught with potential problems: The huge solar arrays, or panels, that will supply the telescope with the power to run its instruments could fail to open, or the lens cap that is designed to protect the delicate telescope from solar radiation could jam. And there is always the possibility that the 43.5-foot-long satellite could bang against the side of the shuttle during deployment.
These or other problems could require Discovery’s astronauts to venture outside the shuttle for telescope repairs. It would be America’s first “spacewalk” since 1985.
The telescope, which is about the size of a school bus, will have to be lifted gently out of the Discovery’s cargo bay by the shuttle’s remote manipulator arm. Astronaut Steven A. Hawley, 38, must perform the difficult task of running the arm perfectly because there is very little clearance between the precious cargo and the sides of the payload bay.
The difficulty of Hawley’s task stems in part from the fact that the telescope will block his view as he lifts it out of the payload bay, forcing him to rely on remote television cameras to guide him through his chore. Furthermore, the robotic arm is like a giant extension of the human arm, except it doesn’t always work perfectly.
Hawley will have to manipulate two hand controls simultaneously, one to lift the telescope and the other to keep it from yawing or pitching back and forth. He will have to move it very slowly, because tolerances are about one inch on each side in the early stage.
“The complexity arises because with large payloads and slow rates the arm doesn’t really give you pure motion,” Hawley said. “You get some cross-coupling because it’s a mechanical device and it doesn’t do purely what it is supposed to do.”
Some of the arm’s joints will slip slightly, and the telescope is so massive that it will tend to drift as Hawley lifts it out of the cargo bay. So if he doesn’t know exactly where it is, and if he doesn’t compensate for any drift, he could bang the instrument into the side of the shuttle as he lifts it up.
“The part that is tricky for me is to make sure that I am able to monitor which way it is going rather than the direction I am asking for, and if necessary correct that,” Hawley said. “But the tolerances are very tight when it is down low (in the cargo bay)--I mean an inch.”
It is fitting that this job should fall to Hawley. He is an astronomer by training, and he spent years at the UC Santa Cruz, studying the distant celestial objects that will be the Hubble’s richest playground.
“I’m not an objective observer,” Hawley said during a recent interview in Houston.
Many of the scientists at the Space Telescope Science Institute in Baltimore were classmates of Hawley’s.
“I know these guys, and they will be watching me,” Hawley said. “I will confess to more nervousness about this” than anything he was asked to do on his two previous flights “because I feel so close to it. I have the opportunity to do this right or not. That bothers me a lot more than the other things I have done.”
Hawley’s role should end--if all goes according to plan--after he has lifted the telescope up to the point where it can be released, a chore that should take about an hour.
But that doesn’t mean the Discovery’s crew will be finished.
Astronaut Bruce McCandless, 52, one of NASA’s most respected engineers who has been working on the space telescope for 12 years, and Kathryn D. Sullivan, 38, the first American woman to do a “spacewalk,” will be ready to lend a gloved hand if they are needed. Their job, if anything goes wrong, will be to go outside and fix it.
McCandless, who was the first man to do an untethered spacewalk in 1984, is a celebrated bird watcher and he admitted he would like to venture outside the spacecraft and try his wings.
“But I would not like the reason for it to be that there is a failure with the telescope,” he said in an interview.
Over the last several years McCandless and Sullivan have spent many hours in a wet tank at the Johnson Space Center in Houston, practicing every maneuver that is likely to be required if the deployment encounters difficulties that can only be solved by sending someone outside.
The training has prepared McCandless and Sullivan for a possible spacewalk, and it has paved the way for future generations of astronauts who will be asked to return to the telescope many times over the next 15 to 30 years to do everything from changing its batteries to adding major instruments.
The Hubble is the first satellite designed to be maintained on orbit by shuttle crews, but the working environment in space is quite different than it is on Earth. So these two veterans have spent years making sure that if something does go wrong, somebody can fix it.
“We have been doing the unselfish job of making sure that someone other than ourselves gets a good setup when they are assigned to a maintenance mission,” said Sullivan, of Woodland Hills. “We have taken a look at everything that isn’t welded on.”
As a result, a number of features, including the electrical connectors, were modified to make the Hubble “user-friendly” for future astronauts.
“We’ve tried to make it so that when some future crew goes up there they will not find any showstoppers,” McCandless said.
This week, however, Sullivan and McCandless could be called upon to make sure there aren’t any showstoppers themselves.
Once the telescope clears the cargo bay, experts around the world will sit on the edge of their seats until the next crisis is passed.
During its trip to orbit aboard the Discovery, the telescope’s batteries will be charged by the shuttle’s electrical system, but the “umbilical” connecting the telescope to the shuttle will have to be disconnected so that the instrument can be deployed.
When it is on orbit, the telescope will use solar panels to collect energy to keep its batteries charged, but the solar arrays must be folded alongside the telescope when it is in the shuttle. So while it is still dangling from the end of Hawley’s robotic arm, the arrays are to unfurl and lock in place, and there are many things that could go wrong during that period.
Experts believe they will have no more than about six hours to get the solar arrays deployed and oriented toward the sun before the batteries run too low. Low batteries could endanger some of the instruments aboard the telescope.
“I’ll be wringing my hands” during that period, said William Taylor, the telescope’s chief engineer.
McCandless and Sullivan will be partially suited so they can leave the relative safety of the shuttle quickly if the solar arrays fail to deploy. They could also be asked to do a number of other chores, like manually remove the telescope’s “lens cap,” called the aperture door.
Once the telescope has been successfully deployed, the Discovery’s commander, Loren J. Shriver, 45, a former Air Force test pilot, will fire the shuttle’s smaller maneuvering jets and drop slowly back from the satellite. The Discovery’s larger jets cannot be used because they might contaminate the area around the telescope, thus negating one of the main reasons for putting it on orbit.
The Discovery will drop back about 40 miles and baby-sit the telescope for a couple of days, just in case it should have to rendezvous and make emergency repairs.
But in Shriver’s view, by that time he will be able to rest a little easier. He is more concerned about the earliest phase of the mission.
“The most disappointing thing for me would be if we couldn’t reach the minimum altitude to set the telescope out and would have to bring it back,” Shriver said in an interview.
Scientists want the telescope to be in an orbit 380 miles above the Earth, thus forcing the shuttle to fly higher than it has ever flown before. That will leave the telescope within reach of future missions, but far enough in space to minimize the contamination from Earth’s atmosphere.
But what if, for any number of technical reasons, the shuttle doesn’t get that high? There is no way for the telescope to boost itself to a higher orbit because it does not carry rockets, which would contaminate its environment.
Scientists say they could live with a lower orbit, about 310 miles, that would allow them to maneuver the telescope and use it scientifically while waiting for a future shuttle mission that could push it higher.
Shriver has argued, however, that any orbit that would keep the telescope up for at least a year would be preferable to bringing it back and trying again later. Re-entry would severely contaminate the telescope, he said, and the delicate instruments could be damaged on landing.
“The scientific community tends to think in terms of the kind of data they want,” Shriver said, “but if they could get an altitude where the Hubble could survive, and if they could get up another flight within nine months to a year, I suspect they would leave it there.”
“Are they going to risk bringing it back and maybe never getting it back up there again?” he asked. He suspects, however, that such a decision would be made only at the level of the White House.
Such is the nature and importance of this extraordinary instrument on which so many careers now depend.
When it is all over--the telescope is projected to operate for 15 to 30 years-- Hawley expects the Hubble to have accomplished “things that are unique.”
“It will be nice,” he said, “to be able to say, ‘gee, I helped do that. I had a role to play in that.’ ”
He said that as an astronomer the mission has special significance for him and he does not rule out the possibility that when his days as an astronaut are over, he may return to astronomy.
But that depends on what happens this week, he quipped.
“The opportunities that will be presented to me will be profoundly different depending on how the flight goes.”
THE HUBBLE SPACE TELESCOPE The Hubble Space Telescope, the most sophisticated satellite ever built and the first designed to be serviced on orbit by astronauts from the space shuttle will usher in a new era in astronomy. The $2-billion telescope, which has the finest mirror ever made, is to be deployed the day after the shuttle Discovery blasts off from the Kennedy Space Center, now set for Tuesday. Astronomer Steven Hawley will lift the schoolbus-sized telescope out of the Discovery’s cargo bay with the shuttle’s robotic arm. If anything goes wrong during the deployment, astronauts Bruce McCandless and Kathryn Sullivan will go outside the Discovery to do whatever is necessary.
Hubble Statistics Mission: The telescope is expected to provide the sharpest images of any telescope ever built because it will be above the distorting effects of the Earth’s atmosphere. Scientists hope it will tell them much about the evolution of the universe and aid in the study of such exotic objects as black holes, quasars and pulsars. And many believe it will discover celestial objects that no one has ever dreamed of.
Length 43.5 feet Diameter 14 feet Weight 25,500 pounds Primary Mirror 94.5 inches Orbit 380 miles
