Repairman In Space
FRANK CEPOLLINA TALKS ENTHUSIASTICALLY ABOUT HIS favorite subject. “Someday we’ll be doing this in orbit around Mars,” he says. This is the technology of satellite servicing, which is his specialty. You probably haven’t heard his name, but you certainly have heard of some of his projects; they include the historic mission to correct defects in the Hubble Space Telescope back in 1993. Finding ways to do meaningful work in the hostile environment of space has been the focus of Cepollina’s career. His successes are the reason he is one of this year’s inductees into the National Inventors Hall of Fame.
The amount of engineering and exertion required to do work in space came as a surprise in the early days of the manned space program. For instance, when the astronauts Eugene Cernan and Thomas Stafford launched into space aboard Gemini 9 on June 3, 1966, they had no way of knowing that a nightmare would begin as soon as Cernan began a space walk.
The plan called for him to take some photographs and enjoy weightlessness for a few minutes before working his way to the rear of the capsule and donning a backpack stored there called the Astronaut Maneuvering Unit, which had thrusters designed to let him zip around in space like Buck Rogers. There was no zipping that day. From the moment he emerged from the capsule, everything Cernan did was much harder than he’d expected. He said his space suit felt like a “rusty suit of armor.” Every weightless movement triggered an equal, opposite reaction, and he found himself repeatedly flying out to the end of the umbilical cord connecting him to the Gemini capsule and then rebounding in an unexpected direction.
Medics on the ground were alarmed when his heart rate increased to 155 beats a minute. He perspired enough to fog his helmet visor, and sweat pooled in his eyes. His struggles split the seam of an insulating layer in the back of his suit, whereupon he instantly felt scalding heat from the fierce, bare sunshine; he would return to earth with painful burns.
Stafford finally ordered Cernan to forget about the $10 million backpack and return to the capsule. Doing so turned out to be the most alarming part of the space walk, as Cernan discovered that his pressurized suit wouldn’t flex enough to allow him back inside. “I fought [the umbilical] for about 30 minutes before deciding that this snake was perhaps the most malicious serpent since the one Eve met in the Garden of Eden,” he wrote in his autobiography.
Then the struggle to close the hatch was so prolonged and difficult that Stafford decided he needed to lie so the ground crew wouldn’t panic. “Coming in, no problem,” he fibbed as he and Cernan improvised a lever to force the latch into position. It finally closed. Stafford said nothing at the time, but afterward he revealed that he’d worried about being forced to return to earth alone, leaving Cernan’s body in orbit.
The experiences of NASA’s first space walkers—Cernan was the second of them—gave birth to the field of satellite servicing. “They pioneered a lot of the technologies we use today,” Cepollina says. First of all, they made clear the need for a change in space-suit design. The Gemini astronauts wore suits inflated to 14 pounds per square inch because that’s about normal pressure on earth. NASA cut the level to 4 PSI, reducing the feeling of working inside an overinflated balloon.
Next the agency had to develop methods for moving about in space. Cernan recommended rigorous practice sessions underwater, where the effects of weightlessness could be mimicked. Today all space walks are rehearsed repeatedly in a huge 6.2-milliongallon pool in the Neutral Buoyancy Laboratory at the Johnson Space Center in Houston.
The main challenge was conquering the exhaustion that Cernan had encountered. “Fatigue was the limiting factor. Our solution was to come up with power tools they could use to reduce fatigue,” says Cepollina. The best known of these is a pistol-grip device that looks like a battery-powered hand drill on steroids. An engineer named Paul Richards designed it while working on Cepollina’s team; he later became an astronaut and got to use his invention on the International Space Station in March 2001. The tool accepts dozens of interlocking accessories that allow astronauts to perform a wide range of tasks.
Cepollina’s own contribution had a longer gestation. At 66 he is now manager of the Hubble Space Telescope Development Project. Gregarious and often smiling, he walks quickly from place to place at the Goddard Space Flight Center and points to landmarks like the world’s largest clean room and a full-size training model of the space shuttle (now not used). He works in a large corner office stuffed with spacecraft models, drawings, and paraphernalia, including several items retrieved from orbit. “I love when we can bring a piece of hardware back from space, refurbish it, and fly it again,” he says.
He earned a B.S. in mechanical engineering at Santa Clara University in 1959 and went to work for NASA in 1963. From the beginning he specialized in designing satellites and spacecraft and looked for engineering solutions that would make satellites more robust. So he was well placed to deal with a problem that emerged in the late 1960s.
“It started in the 1967–69 time frame, when we were losing a lot of brand-new satellites that we put into orbit,” he says. As satellites became bigger, more complicated, and more expensive, NASA and its commercial customers grew increasingly concerned about satellite failures. “There was a push at NASA to look for lower-cost ways to conduct science in orbit.” In 1970 Cepollina was tapped to lead NASA’s effort to design what was called the Multimission Modular Spacecraft. “The idea was that we should design modular spacecraft that came apart and went together very easily,” he says. By 1976 it was clear that NASA would soon fly a space shuttle, making it possible for space-walking astronauts to swap defective components, replace old batteries, or even retrieve whole satellites so they could be repaired on the ground. “So we designed systems that could be serviced by the Shuttle, either on the ground or in space,” Cepollina says.
The first modular craft to fly was the Solar Maximum satellite, which was launched in 1980 to conduct astronomical observations of the sun. Some NASA authorities, Cepollina recalls, thought the idea of satellite servicing was a waste of time and money and that satellites should just be considered disposable. But they changed their minds when Solar Max began to fail, in 1980.
“After less than a year in orbit, we began losing fuses because of a design problem,” Cepollina remembers. Rather than abandon the $120 million satellite, NASA appointed him project manager for the Solar Maximum Repair Mission, and he launched a servicing mission in 1984. The astronaut George “Pinky” Nelson failed in his attempt to grapple Solar Max and, a day later, it was grabbed by the robot arm and hauled aboard the Shuttle, where the defective module was replaced. NASA officials watched closely to see how the new technology performed. “Everybody was standing on the periphery, looking to see if it was going to work,” Cepollina says. “Sure enough, they changed out the defective module in 40 minutes.”
With the grapple-and-repair concept proven, owners of communications satellites began signing contracts for NASA to retrieve and fix their own expensive units. Cepollina was named satellite-servicing project manager and led a team that designed a number of generic components suitable for use in a wide variety of spacecraft, including the Hubble Space Telescope.
The Hubble itself provided the next hurdle for satellite servicing. As space buffs remember, soon after it was launched, in 1990, NASA officials were appalled and embarrassed to discover that the contractor responsible for grinding the almost 8-foot primary mirror had miscalculated in a way that made the telescope incapable of coming to a sharp focus.
This unexpected problem was too serious to fix by simply swapping out a defective module, so Cepollina became project manager of a hurriedly assembled team charged with repairing the telescope. “The first Hubble repair mission took us to the next level of servicing,” he says. His team had to design from scratch new optical elements that could correct the Hubble’s flawed vision yet fit in with the modular instrument design philosophy.
Astronomers around the world were relieved when shuttle astronauts were able to install corrective optics on the Hubble in December 1993. Soon crisply focused images of deep-space objects were being beamed to earth, leading to a series of rapid new discoveries in astrophysics and cosmology.
After the Hubble repair mission, Cepollina was appointed manager of the Hubble Space Telescope Development Project, which is charged with finding ways to use satellite-servicing technology to upgrade the Hubble to perform beyond its initial design requirements. Twice astronauts have replaced the telescope’s solar panels with higher-performance ones. A new, more powerful refrigeration unit is cooling the instrument that detects infrared light, and faster transmission equipment has boosted the Hubble’s data transfer rate from 5 gigabytes a month in 1993 to 180,000 gigabytes a month today.
Most impressive, however, is the installation of a new camera to record the images seen by the Hubble. In March 2002 astronauts put in a radically improved instrument called the Advanced Camera for Surveys. Its higher resolution and improved sensitivity make it 10 times as powerful as its predecessor, and it has produced dramatically sharper images, some of them of stars and galaxies that were invisible to the old Hubble. “After 13 years in orbit, we can still produce a crescendo of discoveries about our universe and as long as we can apply the human design ingenuity to future servicing missions, the pace of discoveries about our universe will continue,” Cepollina says.
Satellite servicing continues to head onward and upward—literally. So far all servicing missions have been conducted in low earth orbit. NASA doesn’t now have the capability to send astronauts to geostationary orbit, 22,000 miles above the equator, but that’s where most of the large, powerful communications satellites are deployed. This high frontier needs attention, Cepollina says, so NASA may eventually develop advanced unmanned spacecraft that can dock with high-orbit satellites to install new batteries, replenish fuel tanks, and boost the satellites to different orbits. These space tugs will likely be robotic, controlled remotely by an operator on the ground.
“I see this as the future of satellite servicing,” Cepollina says. “Ultimately this will provide a way for humanity to do useful work throughout the solar system.”