June 2002: Ask John Charles, STS-107 mission scientist in NASA’s Office of Biological and Physical Research (OBPR), for an early memory of space exploration, and he recalls his disappointment when he wasn’t able to watch the astronaut-carrying Mercury missions on television. Charles didn’t get home from elementary school in time to see them. But he could, he says, pretend to be astronaut (later Senator) John Glenn during recess while lying on his back in the playground dust, looking up at the sky and imagining himself on a rocket roaring into orbit around the Earth.
Charles never did become the astronaut he fancied he might. Instead, he found another way to stay connected to space. By combining his interests in physics and physiology, Charles would pursue a career in biophysics, researching how spaceflight affects the body and helping NASA conduct experiments in space. Now he is the coordinating scientist for the OBPR experiments on the STS-107 space shuttle flight, one of the most science-packed of recent shuttle missions.
“This flight allows scientists to do what scientists do best: ask the kind of questions that we don’t yet have complete answers for,” Charles says. “This mission is yet another example of the kind of investigations that we as researchers are capable of and that we as a society should expect of NASA. All are important in answering the questions inquisitive people have about the universe and our place in it.”
And there are a lot of questions to be asked. Thirty payloads with a total of roughly five dozen experiments will fly aboard STS-107 this summer. A superficial glance at the studies planned for the flight first reveals a diverse array of research with seemingly little commonality. Among the investigations scheduled are ones involving solar radiation, gas viscosity, condensed matter and particle physics, and communications technology. Take a closer and more detailed look at this “mixed manifest” mission, though, and the interrelations are more apparent. Because the majority of the experiments slated during the shuttle Columbia’s 16-day orbital sojourn planned to begin July 19 are of the applied-science kind, the bulk of the research results gleaned are likely to have significant practical impact for taxpayers on the ground.
Eighteen of STS-107’s 30 payloads relate to or involve biology and biotechnology. Several studies, for example, will grow protein crystals, crucial to the creation of enhanced medications with fewer side effects. Others will look at the mechanisms involved in gene transfer and gene expression, while a set of medical experiments (some conducted in flight and others when Columbia lands) will study how calcium is added to and removed from bone. Two studies will determine how viruses spread and are shared within closed environments. A rotating bioreactor, the Biotechnology Demonstration System, will suspend and nurture cells for three-dimensional tissue growth under conditions impossible to replicate on Earth. And, to better understand how sleep is disrupted in space, STS-107 astronauts will wear specialized wrist accelerometers to track disturbed sleep-wake patterns that will likely aid in finding means of minimizing sleep disruption on Earth as well as in space.
“Spaceflight factors – weightlessness, radiation, rapid day/night cycles – give us valuable insights into normal biology on Earth and human health in space,” Charles says. “They enhance our understanding of physiological processes using space as the newest research venue. On Earth, gravity is always present, even during bed rest or [water] immersion studies. Beyond the surface of the Earth, weightlessness will be an important parameter.”
While it is common to refer to the weightlessness of space, in reality those on a spacecraft orbiting 100 to 300 miles above the planet experience from one-thousandth to one-millionth of Earth’s normal gravitational pull as they freefall around the globe. Reduced gravity affects the ways components within complex systems interact, making microgravity an essential parameter for experiments in both the life and physical sciences. Researchers can observe changes to phenomena such as those involved in fluid dynamics and combustion. For instance, in the absence of a strong gravitational field, surface tension becomes more evident while convection-related processes are minimized.
One of Columbia’s physical science payloads is a rugged chamber for conducting studies that will examine the physics of combustion, soot production, and (in a commercial payload) fire-quenching processes in order to provide insight into new means of fire suppression. Another investigation involves the compression of granular materials to further understanding of soil behavior in order to improve prediction of earth movements in areas where earthquakes, floods, and landslides are common. STS-107’s astronauts will also oversee the formation of zeolite crystals, which can speed the chemical reactions that are the basis for industrial and biomedical processes. In addition, mission specialists will conduct research on the properties of xenon as it goes from a gaseous to a liquid state, a transition during which many thousands of its atoms exhibit behavior known as long-range ordering.
According to Charles, NASA selected the life and physical sciences investig9!U=ns for the mission with an emphasis on crew health and safety in preparation for extended orbital stays on the International Space Station (ISS). An independent panel of experts evaluated submitted research proposals for scientific excellence. Ultimately, proposals were competitively selected based upon scientific merit as determined by peer review, programmatic need, and funding availability. In the case of STS-107, scientific experiments were chosen from a queue of research that had already passed NASA’s rigorous and competitive peer-review process. Commercial research followed a separate selection process, with emphasis on the willingness of business and industry to underwrite the experiment, potential market strength, and investment returns from the development of new products.
“STS-107 is an example of a research mission that represents a very productive use of shuttle resources for experiments that have been peer-reviewed and approved in a large number of areas,” Charles says. “All of these investigations have been waiting in line for this opportunity. The space station will be the ultimate venue for these kinds of investigations.”
For many members of the STS-107 science team, the mission’s manifest represents a milestone in careers that often included or even began with dreams of traveling in space. Imagination can pay off – benefits derived from their research could have far-reaching impacts.
Perchance to Dream
The STS experiment led by Principal Investigator Charles Czeisler to study astronaut sleep patterns has allowed Laura Barger to realize two aspirations at once. “STS-107 is a good way to combine my interest in sleep and circadian rhythms with spaceflight,” says Barger, a research fellow in medicine at Harvard Medical School and Brigham and Women’s Hospital in Boston, Massachusetts.
After a 10-year stint as an Air Force navigator on a KC-135, a refueling airplane, Barger entered a graduate program and toyed with the idea of becoming an astronaut. But a specific kind of research interest would take priority and, eventually, lead her to space in a less direct route. “I did a lot of traveling across time zones in the Air Force,” Barger says. “I experienced jet lag firsthand. That’s when I became aware of the importance of circadian rhythm research.”
Circadian rhythms are biological patterns that oscillate within a 24-hour period. Most organisms experience a pattern of rest and activity that repeats every day. Disruption to these patterns can have a profound effect on the sleep-wake cycle in earthbound individuals and astronauts alike. Too little slumber can lead to mental and physical impairment, interfering with concentration and potentially affecting immune system functioning.
Research suggests that sleep-deprived individuals can become, and remain, sicker (usually with garden-variety viruses and, perhaps, with more serious diseases, like heart attacks and cancer) than those who sleep normally. Certainly, sleep deprivation and/or disturbance is a chronic issue for shift workers. Those who work alternate shifts have repeatedly complained that sleep, even when obtained, is usually of shorter duration and not as restful as that experienced on a regular schedule.
The research team at Harvard Medical School and Brigham and Women’s Hospital has designed a “sleep actigraphy” experiment that will examine the degree and extent to which sleep is disturbed or interrupted for the STS-107 mission astronauts. Barger says that astronauts don’t sleep all that well before a mission because of excitement, anticipation, shifting of sleep times to accommodate the launch schedule, and the increased pace of preflight operations. Once in orbit, sleep is hard to come by as well; previous studies have shown astronauts sleep one to two hours less per 24-hour period in space than on the ground. Part of that disruption may be due to novel surroundings, spacecraft noise, workload, and high adrenal activity, but a more significant part may also be due to the misalignment of circadian rhythms normally set on Earth by the 24-hour light-dark cycle.
“During shuttle flights, the light-dark cycle is about 90 minutes long,” Barger explains. “Seeing a sunset and sunrise every 90 minutes can send potentially disruptive signals to the area of the brain that regulates circadian rhythmicity. Additionally, the lighting onboard the space shuttle might not be sufficiently intense to maintain circadian alignment. Consequently, sleep could be disturbed. If the astronauts sleep one to two hours less per night, over a 16-day mission, that can add up to a 32-hour sleep deficit.” Such a deficit may have performance consequences, possibly affecting the monitoring of experiments. Barger also points out that the consequences for long-term space travelers are unknown. “If we’re to go any farther, say, on missions to Mars,” she adds, “we have to understand how the human body will cope for extended periods.”
STS-107 astronauts have volunteered as test subjects for the sleep study. Researchers want to know if light levels inside the shuttle are inappropriate for maintaining normal circadian rhythms, if astronauts have a harder time falling asleep, wake more frequently, and are not as satisfied by the quality of their sleep. Ninety days before launch, astronauts’ sleep patterns were monitored to establish a baseline of what “normal” sleep is like for each individual; in orbit, the astronauts’ sleep will be compared to their baseline measurements.
Each volunteer astronaut will wear a watch-sized actigraph, essentially a computerized accelerometer that records wrist movement in any direction. Increased wrist activity indicates that an individual is awake; thus, by monitoring wrist activity, sleep-wake patterns can be established. A light-sensitive diode on the device will track and record light levels, so that activity and sleep can be correlated with light exposure. Placing the actigraph directly on a specialized reader downloads its stored data wirelessly to a computer. Researchers will then be able to correlate objective criteria with astronauts’ subjective experiences, recorded in a daily sleep log, in order to evaluate the degree of sleep disruption.
This is the third time this experiment has been conducted, with three more sleep-disturbance studies planned for upcoming shuttle missions. Repeatability is key; having multiple test subjects increases the likelihood of obtaining meaningful data while eliminating the role of chance in outcomes. “It’s a relatively simple experiment that we’re hoping will generate a lot of valuable information,” Barger says. “We hope to be able to recommend countermeasures that will help astronauts sleep soundly.” Eventually, anyone whose sleep is disturbed could also benefit.
Vascular Health in Space
Principal Investigator Michael Delp, an associate professor in Texas A&M University’s Department of Health and Kinesiology, has also designed an experiment that may bring answers to health problems for astronauts and earthbound individuals alike – as well as an opportunity to participate in the “camping trip” of his dreams. As a child, Delp wanted to be either a park ranger or an astronaut. “It was that sense of adventure,” he says. “I always liked camping and being in the outdoors. To me, microgravity is the ultimate outdoor adventure.” Delp hopes his research in vascular health will help to make the adventure of space travel safer for those who do take their sleeping bags into orbit and beyond.
As one of the designers of an STS-107 experiment to measure blood vessel response in gravity’s near-absence, Delp will directly gauge some of the detrimental effects of spaceflight. Because the human cardiovascular system is well-adapted to the constant gravitational force of the Earth – vessels in the legs, for example, constrict to prevent blood from collecting in the lower extremities – its absence causes physiological dysfunction. Blood vessels are made up of smooth muscle, which atrophies unless challenged by gravity. In reduced gravity, smaller vessels lose the ability to either dilate or constrict. The effect is intensified by duration; the longer the time without sufficient gravity, the weaker the circulatory system becomes.
Microgravity also decreases head-to-foot arterial blood pressure gradient, shifting fluids from the lower to the upper portions of the body. In turn, this triggers adaptations within the cardiovascular system to accommodate the new pressure and fluid gradients. By the time the subject returns to normal gravity, blood vessels have become “deconditioned” for Earth living, losing the ability to push blood to the brain. Without adequate blood supply, the brain shuts down, and the individual faints. Upon returning to Earth after missions of more than a few days, most astronauts become dizzy when standing upright. Sixty percent cannot pass a 10-minute stand test without losing consciousness, a condition known formally as orthostatic intolerance. With stays on the ISS lasting for months, and potential interplanetary travel expected to last two years or longer, ways must be found to compensate. First, however, circulatory mechanisms must be precisely understood in order to develop effective countermeasures.
“Gravity pulls blood down to the feet normally. Arteries resist that pull,” Delp explains. “In microgravity there’s no weight bearing. The body responds to the lack of force by remodeling itself. Look at what happens if a weightlifter stops
working out. If a muscle is no longer stressed, it loses mass.”
In an effort to understand the mechanisms of these cardiovascular adaptations at the cellular and vascular levels, Delp will intensively analyze the postflight tissue of rats flown on the July shuttle flight. His hypothesis is that, in microgravity, blood vessels in rat hind limbs become thinner and weaker and constrict less in response to pressure changes and to chemical signals essential to vascular health. The physiological alterations should be apparent. Because rats react more quickly than humans to space-induced physical change, Columbia’s 16-day mission is the human equivalent of several months in microgravity.
The rats will be housed in special enclosures that have been used successfully on a number of prior shuttle flights. The crew will make daily health checks and will replenish the water supply as needed. Following landing, the small blood vessels in hind limb skeletal muscles that provide blood-pressure resistance will be analyzed for their responses to chemical signals and pressure changes, and for changes in vessel structure and gene expression.
Delp expects the experiment to yield crucial information on the basic physiological responses of individual blood vessels involved in blood flow and pressure regulation. Data derived from the examinations should eventually result in the development of treatments or countermeasures to improve crew health and performance following their return to Earth. The study is also expected to aid the elderly, who can be injured as a result of vascular deterioration.
“There are similarities to what happens in microgravity and what happens in old age,” Delp points out. “When the elderly go to the emergency room, the reason is likely due to orthostatic intolerance, either directly or indirectly. They can’t stay upright, and when they do go down, they injure themselves.”
The eventual goal, he believes, is to develop devices or procedures for space travel that will pull blood down to the feet so that vessels will experience a rough equivalent of gravity levels at Earth’s surface. In the short run, though, he hopes the experiment will provide information that can be used to counter microgravity’s effects for astronauts living on the space station, who face longer periods of vascular recuperation after returning from extended station assignments. And for Delp, there is the personal satisfaction of understanding that which was unexplored and unknown.
“For me, this has been a great personal experience. It’s been one of the highlights of my life,” he says. “I like research so much because I love the sense of discovery. You get that with NASA.”
On Less Than Solid Ground
The promise of discovery from the STS-107 mission has made Buddy Guynes delay his retirement “several times,” as he awaits results from the flight of the Mechanics of Granular Materials (MGM) experiment. Guynes is a researcher at NASA’s Marshall Space Flight Center, where he also serves as MGM project manager. “The possibility of retirement is appealing to me, but I want to work for a good while yet,” Guynes says. “I’m expecting exciting results from the mission and would like to have a hand in getting the good news out to the public.”
The physical phenomenon that MGM investigates can be experienced firsthand by anyone who buys a rock-hard package of vacuum-packed coffee at the local supermarket. Rip it open, says Guynes, and what was brick-solid suddenly becomes a soft and easily shifted mass of ground coffee beans. A straightforward change in environmental conditions – in this case, inrushing air that releases the contents from their confinement – drastically changes the properties of a bulk granular material. Once the vacuum is gone, the grains move about freely, almost like a liquid. What affects ground coffee can also affect saturated, loose soils during earthquakes, collapsing structures previously thought strong and stable.
“Before that air comes in, you can almost use that coffee [package] like a hammer,” Guynes says. “As soon as you let air in, it gets real loose. The soil [effects] you see in an earthquake can be similar, especially if there’s water around. Water is a lubricant between the grains. When they’re shaken, they also get loose.”
The principal strength of soils beneath a house or sand under a rover’s wheels on Mars is the friction and geometric interlocking between the faces of individual grains. But this geometry can also cause weakness: the grains’ craggy surfaces stick and form small voids, making soils or powdery substances behave like a liquid when moisture and air are trapped within and particular conditions or stresses are encountered. Stresses can build faster than entrapped fluids can escape. As outside pressures increase, intergranular pressures decrease, weakening and softening the material. When the external loading equals the internal pressure in the spaces between the grains, the material liquefies. During liquefaction, soil-water composites momentarily become viscous, causing buildings to sink and tilt, bridge piers to move, and buried structures to float.
During the STS-107 flight, the MGM experiment will use microgravity to test sand columns under conditions that cannot be mimicked on Earth. In orbit, the weight of the specimen sand is no longer a factor, and stresses are uniform. This yields measurements that can be applied to larger problems on Earth. MGM scientists will study load, deformation, and fluid pressures, as well as changes in soil structure, including the formation of shear bands and changes in density.
The heart of MGM is three specimen cells containing columns of sand held in a latex sleeve and squeezed between metal plates made of tungsten. The specimen assembly is contained and compressed for more than one hour in a water-filled jacket made of an exceptionally strong plastic known as Lexan. A load cell measures forces, and three cameras videotape the experiments. The flight crew controls the experiment through a laptop computer. In all, nine experiments will be conducted on the trio of cells.
After return to Earth, epoxy will be injected to stabilize the sand columns for handling. The edge profiles will be photographed. Computer tomography scans then will produce a series of finely pixilated images rendered in three dimensions for detail. Finally, the columns will be sawed into 1-millimeter-thick disks for even closer inspection under an optical microscope.
MGM has flown on two earlier shuttle missions (STS-79 in September 1996 and STS-89 in January 1998). Those findings are already helping scientists test a number of hypotheses about soil behavior. Scans of earlier MGM specimens, for instance, have revealed internal features and patterns not seen in specimens tested on the ground.
Knowledge derived from the STS-107 MGM study will help scientists design models of soil movement under stresses. The models can then be applied to strengthening building foundations, managing undeveloped land, and handling powdered and granular materials in chemical, agricultural, and other industries. Eventually, scientists should better understand the geophysics of wind and water erosion of soil, slope development and decay, and the deposit of volcanic materials. Specialists may also improve techniques for the storage, handling, processing, and management of coarse-grained materials and powders, including those used in silos, powder feeders, conveyors, and systems for processing coal, ash, limestone, cement, grain, pharmaceuticals, and fertilizers. Also affected will be coastal and offshore engineering, and off-road vehicle engineering.
“This series of experiments could improve foundations for houses, protect buildings during earthquakes, and even prevent clogging in grain elevators. We might end up changing our building techniques,” Guynes asserts. “This is one of the things that NASA is doing that has a very strong application for the guy on the street.”
While Guynes dreams of solving some of the practical
problems of builders on Earth, Michael Jacox, deputy director of Texas A&M’s Commercial Space Center for Engineering, hopes STS-107 results will help point us to the stars. Jacox, who is the program manager for the mission’s StarNav experiment, has been looking to the distant points of light since he was a boy. A self-described fan of Star Trek, Jacox says since youth he was intrigued by space exploration. “I grew up thinking I’d be Captain Kirk,” he says. “I always had a fascination with the stars. I was an amateur astronomer as a kid.” He remains an avid star-watcher and, as a father of five, has been known to take his children stargazing on clear Texas nights.
His stellar avidity has come in handy, as Jacox is directing the deployment onboard STS-107 of a next-generation navigation and tracking device, StarNav-1. StarNav began with a project, led by professors John Junkins and Tom Pollock, in the aerospace engineering department at Texas A&M University. NASA has utilized Junkins’ algorithms, mathematical models, and control logic in a number of space missions, beginning with the Apollo missions to the Moon. Since founding Texas A&M’s Center for Mechanics and Control in 1992, Junkins has concentrated on the creation of sophisticated devices, including patented laser sensing tech-nology for applications in navigation, machine vision, and multimedia.
StarNav pinpoints stars as reference points to determine the attitude and position of a spacecraft. The device takes pictures of stars, matches them with a star catalog, and then uses those pictures to identify in which direction the craft – in this case, Columbia – is pointed. If the StarNav experiment on STS-107 proves its mettle, spacecraft could one day navigate autonomously, without human intervention. StarNav is relatively small, roughly the size of a shoebox, weighs much less than conventional star trackers, and when commercialized, is expected to retail for perhaps half the $1 million per-unit cost of conventional navigation devices.
The StarNav project is involving groups of elementary school students, who will be able to track stars on classroom computers during part of the mission. The collaboration is a result of a joint effort coordinated by the Society of Mexican American Engineers and Scientists with the participation of the engineering center. “The whole project is a combination of advancing a key technology for spacecraft systems while motivating kids to go into careers in space and engineering,” says Jacox. “The innovation is the algorithm. The software we call LISA, for Lost-in-Space Algorithm.”
There are particular challenges putting together a tracking camera that will perform well while holding up to the harsh environment of space. Special kinds of thermally stable steel were used to hold the lenses in place, and care was taken to isolate the interior microprocessors to protect them from the vibration of launch. Plastic components were coated to resist off-gassing – in the absence of atmospheric pressure, organic compounds will evaporate into space – and copper wiring was installed to channel heat to cooler areas.
Two StarNav versions are under development. StarNav-1 will fly on STS-107, and an upgraded successor version, StarNav-2, is slated to fly on a NASA Earth-observing satellite scheduled for launch in late 2004.
“Our goal here is to commercialize space technology. There are real opportunities in space,” Jacox says. “More fundamentally, I think human beings need to explore. Space is the real frontier. Exploration doesn’t just open up new opportunities. It also provides us with hope.”
Web Links
/sts-107/ – Space Research and You — OBPR’s Special Feature on the STS-107 Shuttle Research Mission: Experiment Information, Articles, and Mission Resources.
http://peer1.nasaprs.com/cfpro/peer_review/ltb1_00.cfn?id=417 – 2000 OBPR Research Taskbook — For a summary of the sleep research being conducted by Czeisler, Barger, and other team members see their reports in the 2000 OBPR Taskbook.
http://research.hq.nasa.gov/taskbook/search/retrieve_task.cfm?task_id=147 – 2001 OBPR Research Taskbook — To read about Delp’s ground research on blood vessels conducted in preparation for STS-107 their reports in the 2001 OBPR Taskbook.
http://www.asgsb.org/factsheets/cardiovascular.html – American Society for Gravitational and Space Biology — Information on how NASA cardiovascular research is benefiting science in space and on Earth.
http://jap.physiology.org/ – Othostatic intolerance after spaceflight — For more information on the Spacelab orthostatic intolerance studies see: Buckley, J., et al (1996), Journal of Applied Physiology, 81, 7-18.
http://mgm.msfc.nasa.gov/mgm.html – Mechanics of Granular Materials — To find out more about the Mechanics of Granular Materials experiment visit the project Web site.
http://jungfrau.tamu.edu/~html/StarNav/index.html – StarNav — To find out more about the StarNav experiment visit the project Web site.
http://engineer.tamu.edu/tees/csce/ – Texas A&M’s Commercial Space Center for Engineering — To find out more about the Texas A&M’s Commercial Space Center for Engineering visit their Web site.
