In December 1968, Apollo 8 was the first Apollo mission to use the Saturn V rocket. DU alumnus Doug Krouse (BA '50) was on the team that designed the rocket.
DU’s Joel Williamsen peers at a ragged, gaping hole in the metal sheet he is holding. “This,” he says, “is what a two-centimeter object can do to the hull of a spaceship.”
The hole is several inches across — almost big enough to put a fist through. Metal peels back from the edge like sections of banana skin. A hole of this size could cripple a spacecraft and endanger the entire crew.
So it was no laughing matter when a one-millimeter object — probably a chip of paint from the defunct Mir space station, Williamsen says — struck the International Space Station last May at about 15,000 miles an hour. But the ship sustained no damage and the three astronauts aboard remained safe because the projectile slammed into a protective shield designed by Williamsen and others at NASA. The paint flake blasted clean through the station’s guard plate, but the impact dispersed the object’s energy, breaking the chip into a spray of tiny fragments that clanked harmlessly off the hull. Houston, we don’t have a problem.
Williamsen, who directs the Center for Space Systems Survivability at the University of Denver Research Institute (DRI), can’t guarantee that his shields will deflect every cosmic torpedo. But he can reduce the odds of a spacecraft sustaining a disabling blow and increase the chance that, if it does, the occupants will live to tell the tale.
He helped design the space station shielding in the mid-1990s during an 11-year stint as a NASA engineer. Since setting up shop at DRI in 1998, Williamsen has worked on an array of advanced safety systems, including an emergency patch kit, a depressurization sensor and a computer modeling program to isolate the most vulnerable areas of a spacecraft.
And the International Space Station is vulnerable — like a sitting duck in a shooting gallery. So is every satellite or spaceship in low-Earth orbit. That trajectory is cluttered with thousands of pieces of space junk —bolts, screws, mounting pins, coils of wire — left over from 40 years of human space exploration and satellite deployment. At any given time, Williamsen estimates, there are three million kilograms of this garbage whizzing around the Earth at velocities 10 times faster than the fastest terrestrial bullet.
Ironically, much of that material reflects the work of Williamsen’s predecessors at the University of Denver. Since the formation of the National Aeronautics and Space Administration (NASA) in 1958, DU faculty, researchers, and alumni have been active participants in the U.S. space program in areas ranging from engineering to computer science to defense systems to deep-space astronomy. As NASA’s mission has evolved, so too has the role of the DU community. DU-trained engineers helped build the Apollo rockets. Astronomers and physicists have worked on the space shuttle, the Hubble telescope and deep-space probes. And a new generation of specialists, Williamsen included, is tackling challenges like comet flybys and the search for new planets.
Making space survivable
About 30 years before Joel Williamsen brought the Center for Space Systems Survivability to DRI, William McClain, BA ’52, PhD ’69, made his own contributions to spaceship safety.
Read more about the resurgence of the University of Denver Research Institute.
McClain worked at DRI in the 1960s while pursuing his doctorate in chemical engineering. NASA was leading the nation’s headlong rush toward the moon, and the agency was working with scores of manufacturers and scientists to assemble the Apollo rocketry. A specialist in real-time spectroscopy, McClain won a contract to examine a critical problem.
“They were testing the attitude control engine, which makes very small thrusts to control the positioning of the spacecraft,” McClain recalls. “NASA had test-fired the engine 300,000 times, and it detonated three times — once every 100,000 firings. On a lunar mission, they would need to fire that engine 800,000 to 900,000 times, so statistically speaking it was a near certainty that they would have a explosion.”
McClain traced the problem to a residue left by one of the two chemical agents that fueled the engine. Because they burned on contact, the two agents had to be released with split-second precision; a lag of one-thousandth of a second, even one ten-thousandth, would deposit a speck of unburned matter. Over the span of several hundred thousand firings, a critical mass of this material might build up, and the intensely high pressure in the system could cause it to explode.
“One of those detonations would crack the capsule wide open,” McClain adds. “Not real sanitary when you’re going back and forth to the moon.”
A simple reduction in pressure ratios eliminated the risk of explosion, clearing the way for the moon shots. McClain, though, believes the Apollo 11 crew remained nervous about this particular problem.
“One of the first things the astronauts did on the moon was to look at the back of their motor,” McClain says. “I always wondered whether they were looking for that residue.”
McClain’s work helped prevent a catastrophic accident. The work of another DU alumnus, Harold Secrist, BA ’62, helped NASA to recover from one.
Secrist, who passed away last year, played a key role in developing the Apollo Mission Simulator, a training instrument that helped astronauts prepare for lunar flights. When Apollo 13 suffered a devastating explosion en route to the moon in 1970, the simulator proved crucial in the effort to rescue the crew. It allowed ground personnel to troubleshoot and piece together solutions that they relayed to the imperiled astronauts. Without the simulator, it’s unlikely the crew could have been saved.
The moon missions, says Doug Krouse, BA ’50, were the golden age of the U.S. space program. He witnessed every phase of the program’s development during his career as a mechanical systems engineer working on NASA projects for Boeing, Chrysler, Martin Marietta, North American Aviation and other major contractors. “An aerospace engineer is sort of a high-paid migrant worker,” he jokes. “You go wherever the contracts are.”
In 1965 North American Aviation held the contract to develop the second stage of Saturn V — the booster rocket used in the Apollo missions — and Krouse joined the test-firing team. A year later he took a job with Boeing to help develop the first stage. “In those days each unit had to be test-fired individually,” he recalls. “We blew up the very first stage we tested.”
The kinks were ironed out, and Krouse and a co-worker decided to sneak onto a beach near Cape Kennedy for a close-up look at an Apollo launch. “It was a closed area,” he says. “We could never have done it with the security they have nowadays, but back then things were looser. We could see the rocket on the pad, and then it lifted off and the thing flew right over us. Oh my God. It shook us so hard it made us nauseated. It was so bright you couldn’t look at it. You couldn’t block out the noise. We had to jump into our car and put our hands over our ears; that was the only way we could stand it.”
Krouse also worked on the boosters for Skylab — the 1970s-era space station — and the space shuttle before retiring in 1996. He helped develop a system for applying polyurethane insulation to protect the fuel tank of the space shuttle’s rocket, but he remains most proud of his achievements with the Apollo program.
“Those astronauts, they were fearless,” he says. “We’d design a system, and NASA would call a briefing for their engineers; the astronauts would be there, too. And they would always ask the most incisive questions, always be the first to notice where you didn’t have enough backup. They were not only brave but also intelligent. I really respected them. They were risking their lives, and you felt you owed it to them to do your best.”
“When you have that much at stake,” adds McClain, “you need to know what you’re doing.”
Probing the firmament
“I had the privilege of working at NASA with some of the giants of the space program,” says DU astronomy professor Robert Stencel. “Some of the administrators of the 1960s were still there, and they had accomplished amazing things. There was a culture of pride and determination to make things happen.”
Stencel joined NASA in 1978 while it was in the midst of a transitional period. During his seven years there, the agency shed its single-minded focus on moon landings and embraced a wide range of new initiatives including the space shuttle, the Hubble telescope and Mars landing probes. Stencel himself served as the scientific program manager for two shuttle missions in the 1980s, selecting and preparing astronomical experiments for the flight crew to conduct. On one mission, he sent up two telescopes to measure ultraviolet background radiation and resolve competing theories about the level of this radiation in the Milky Way. The following year, Stencel scheduled a payload of three telescopes to beam back pictures of Halley’s Comet, but that mission was scrapped after the space shuttle Challenger exploded.
Stencel spent most of his NASA years tracking and gathering data from a small fleet of astronomical satellites, and since joining the University in 1993, he has continued to work on NASA projects. He provided critical ground support for Galileo, an unmanned probe that flew past Jupiter in the mid-1990s; project leaders relied in part on Stencel’s infrared images of the giant planet to program the probe’s observations. His current research revolves around the Space Infrared Telescope Facility, which Stencel describes as an infrared version of the Hubble telescope. Set to launch next year, it will be used to look for planets outside of our solar system and to develop theories about star evolution and aging. Stencel and DU astronomy doctoral student Colby Jurgenson also are developing a ground-based version of the infrared telescope.
“We already have a pretty good idea about how stars are born, live and die,” Stencel says. “This new device will help us piece together a more complete scenario of what happens to them as they age, and what will someday happen to our own sun.”
Michelle Creech-Eakman, PhD ’97, one of Stencel’s former doctoral students, conducts similar research with the Keck Interferometer, a ground-based star gazing instrument now in development atop Mauna Kea in Hawaii. Its primary charge will be to develop a catalog of solar systems near to our own, with particular emphasis on finding Earth-like planets.
“I would not say exploration of those planets is an immediate goal,” Creech-Eakman says. “Certainly not for many years. The far more important thing in the short term is to develop a better understanding of our own solar system by comparing it to other ones.”
Such purely scientific objectives have always been an important part of NASA’s mandate, Stencel points out. “If you go back to the National Space Act of 1958, it set forth a variety of missions, and one of them is technology development and transfer,” he explains. “We’re trying to solve impossibly tough problems, and in the course of solving those problems we develop highly skilled scientists and engineers, some of who go on to achieve remarkable things that benefit society as a whole. We are also developing a fabulous archive of basic data. Unfortunately, we don’t have enough people chewing on that data to extract every ounce of value.” But over time, Stencel believes, it may spin off new technologies or theories with far-reaching effects on people’s day-to-day lives.
That sort of knowledge migration has already happened many times over, Krouse says. “The space program is where you push the margin. That’s where you get to the next step. You have to push your computers to greater speed, push all the materials you’re using, push your people. Today we’re all used to microcomputers, micromedicine, satellite communications. Well, NASA’s the one that pushed all that stuff.”
“The most important thing NASA can do,” Stencel adds, “is to inspire people, especially young people. It has to do remarkable things, things which tap into the innate curiosity people have about space. For example, we now know about the possibility of an asteroid collision with the Earth. I think we should be conducting maneuvers on near-Earth asteroids, practicing landings and flybys. It would be very exciting, as well as a gigantic engineering challenge.”
Not to mention a multimedia spectacular. “Imagine the streaming video from that spaceship,” Stencel laughs.
Engineering the future
NASA’s Deep Impact project may have just the inspiration factor Robert Stencel talks about.
Set to launch in January 2004, it will produce the first-ever look inside the head of a comet. A small, unmanned probe will fly out to meet comet Tempel 1 and crash a 750-pound spacecraft onto the surface at a velocity of 7 miles per second. The resulting crater, about the size of a football stadium, will reveal some of the oldest matter in the solar system, and, it is hoped, yield new insights about how our planet and its neighbors formed.
“But here’s the tricky part,” says Joel Williamsen, who will design the shields for the probe. “The ship has to get very close to this comet to deliver its payload. It will actually fly through the tail of the comet. While it’s going through the comet, it’s taking pictures the whole time but also getting sand blasted by the tail, which is just a long stream of cosmic dust particles. Our job is to protect the crucial instruments — the camera, the batteries, the thrusters — while they fly through the tail. And we’re only allotted 25 kilograms of shielding. That’s not very much.”
He smiles broadly. “For about five minutes there, we’re going to have a real wild ride.”
The ship will drop its spacecraft “bomb” on July 4, 2005, and the explosion will be visible from Earth. If Williamsen’s shielding is successful, the probe will beam back pictures in near real-time, and a live television broadcast is planned. “It’s going to be the greatest fireworks show you’ve ever seen,” Williamsen says.
Between now and then, he and his five-person team at the Center for Space Systems Survivability — Hilary Evans, Bill Bohl, Tim Gordon, Don New and Ron Miller — have more than enough to keep them busy. They have already begun work on a new heat shield for the space shuttle. The current version is made up of ceramic tiles, which get chipped or otherwise damaged during re-entry and have to be repaired before the shuttle can fly again. The repairs are costly and cause long lag times between missions. Williamsen’s new shield, which incorporates layers of metal and foam, is designed to be far more resistant to damage.
Williamsen also has proposed to design shielding for the Hubble 2 telescope, slated for a 2008 launch. The telescope will be stationed about a million kilometers away from earth — twice as distant as the moon — and far above the flurry of man-made debris that floats in low-Earth orbit. However, it will still be exposed to meteor showers, solar storms and other natural hazards. Williamsen’s primary task will be to protect the telescope’s sun shade, a giant visor that keeps solar rays from heating up Hubble’s enormous mirrors. Even a small penetration of the sun shade could impair the telescope’s performance.
He also remains heavily involved with the International Space Station, which, despite its coat of protective shielding, stands about a 20 percent chance of a penetrating impact.
“If an object is 10 centimeters or larger,” Williamsen explains, “it shows up on radar and the space station can navigate around it.” (The space station has already taken two such evasive actions.) “If it’s about two centimeters or smaller, the shields will stop it. But it’s those objects between 2 and 10 centimeters that we still have to worry about.”
Accordingly, Williamsen has turned his attention to developing tools and procedures that can be used in the event of a penetration. One of his survivability center associates, Research Engineer Don New, MS ’93, is developing a hand-held sensor that will enable flight crews to pinpoint the damage in short order and seal off that portion of the ship. DRI research engineers Bill Bohl and Hilary Evans are developing a computer-modeling program that will assess which portions of the space station are at the highest risk of an impact. Williamsen and Bohl also devised an emergency patch that can be applied from outside the ship during a space walk, temporarily plugging the hole; the crew can then re-pressurize the cabin and make a more permanent repair from inside. This process was featured in the 2000 film Mission to Mars in a sequence based on DU’s patch technology.
The Center for Space Systems Survivability promises to become a training ground for the next generation of NASA scientists. Williamsen already has one DU graduate student, Brooke Myers, in the fold. Funded by NASA, she is examining the effects of temperature on the International Space Station’s shields.
“In the sun, the surface of the shield may get up as high as 200 degrees Celsius,” says Myers, who is pursuing a master’s degree physics and astronomy. “In the dark, it may drop down to 20 below. The question I’m trying to answer is whether those temperatures have any effect on the likelihood of penetration.”
To gather data for the study, Myers has been using a .32-caliber light-gas gun — dubbed “the fastest gun in the West” — to simulate space-debris impacts. Housed at DRI’s East Test Range facility on the prairie near Watkins, Colo., the gun fires pellets at speeds of about 4 miles per second—roughly the velocity of a piece of orbiting space junk.
“This has been my dream since I was about 8 years old,” Myers says. “I’ve always wanted to be a part of the space program — maybe even the astronaut corps. I have a strong interest in going to Mars, but I’d settle for any extraterrestrial mission.”
This August, space shuttle astronaut Christopher Loria presented Joel Williamsen with a Silver Snoopy Award. Voted on by astronauts themselves, the rare honor recognizes “outstanding performance contributing to flight safety or mission success.” Hilary Evans, who is stationed at a NASA facility in Huntsville, Ala., received a Silver Snoopy in 1998. The citations symbolize the many achievements of DU students, researchers and alumni in support of efforts to better understand the universe. They show that, even after 40 years, the spirit of space exploration remains alive and well at the University of Denver.