Bound for the moon

The next rover to roam the moon’s surface

may come not from nasa and its rocket scientists

but from college students and

private companies working on a shoestring

By Michael Belfiore

On a muddy, rubble-strewn field on the banks of the Monongahela River in Pittsburgh, a five-foot-tall pyramidal robot with twin camera eyes slowly rotates on four metal wheels, its electric motors emitting a low whine. In a nearby trailer, students from Carnegie Mellon University huddle around a laptop to watch the world through the robot’s eyes. In the low-resolution grayscale images on the laptop’s screen, the rutted landscape looks a lot like the moon, which is the robot’s ultimate destination. Carnegie Mellon robotics professor William “Red” Whittaker and his students built Red Rover to win the Google Lunar X PRIZE, a competition designed to boost the role of private companies in space and inspire innovation in spaceflight technology. The winning prize is $20 million, which will go to the first nongovernment team that lands a robot on the moon, gets the robot to travel half a mile or so, and sends high-definition video back to Earth—all by the end of 2015. A second-place prize of $5 million, along with bonuses for other achievements such as reaching the site of an Apollo landing, brings the total purse to $30 million. Although 26 teams are competing, Whittaker’s team is a clear leader. His firm, Astrobotic Technology, was the first team to make a down payment on a rocket that will carry its spacecraft and rover to the moon. Whittaker has also proved himself to be a champion builder of autonomous vehicles that can navigate extreme environments. The Google Lunar X PRIZE comes at a major turning point for the U.S. space program. In 2010, following the recommendations of the Review of U.S. Human Space Flight Plans Committee, President Barack Obama directed NASA to encourage privately owned and operated spaceships to replace the retiring space shuttle. With input and seed money from NASA, the reasoning goes, private companies can design and construct ships more quickly and more affordably than the usual big contractors can produce vehicles for the government agency. In the same spirit, the Google Lunar X PRIZE seeks to foster a new class of private planetary missions, one that does not depend on expensive one-off spacecraft and political commitments that may not last beyond one administration. Instead researchers would pay private companies to launch their rovers and instruments. NASA has added its own incentives—an additional $30.1 million, split among six teams for surmounting technical feats that have stumped many government rovers, such as surviving the lunar night. The fate of private spaceflight companies after the Google Lunar X PRIZE is far from certain, and not everyone is convinced that a market exists for their services, but many researchers are excited about the prospect of commercially funded space science. TEST LAUNCH the contest has a precedent in the $10-million Ansari X PRIZE, which ended in 2004, when SpaceShipOne became the first privately manufactured manned vehicle to leave the atmosphere. SpaceShipOne was a rocket plane built by Mojave, Calif.–based Scaled Composites, with funding from Microsoft billionaire Paul Allen. Virgin Galactic is now financing SpaceShipTwo. It has received more than $60 million in deposits from individuals who are willing to pay $200,000 each for the chance to float in microgravity and see Earth from a distance. NASA has contracted Virgin and six other private companies to fly scientific equipment onboard SpaceShipTwo and other spacecraft to conduct experiments on challenges such as transferring fuel without gravity. Now the organizers of the Google Lunar X PRIZE hope to duplicate this success for robotic planetary missions. Few people are as qualified to get a robot on the moon as Red Whittaker. The 63-year-old may have done more than any other individual in developing the discipline of field robotics— taking robots out of controlled environments such as automobile factories and releasing them to do useful work in the wild. In the 1980s he designed and built the robots that explored damaged and dangerously radioactive areas of the partially melted-down Three Mile Island nuclear power plant. As founder and head of the Field Robotics Center at Carnegie Mellon, Whittaker has since made a career of breaking new ground in autonomous vehicles. He has created robots that hunt meteorites in the ice fields of Antarctica and robots that climb into the craters of active volcanoes in Alaska and Antarctica. Whittaker began planning for the Google Lunar X PRIZE in 2007 while in the midst of a different competition: the Defense Advanced Research Projects Agency’s Urban Challenge, held at the former George Air Force Base in Victorville, Calif. Under the team name “Tartan Racing,” Whittaker and his students partnered with General Motors, Continental and other sponsors to create a driverless Chevy Tahoe named “Boss.” Even as he won a first-place victory in the world’s first autonomous vehicle race through city streets, Whittaker wasted no time in finalizing plans for a class at Carnegie Mellon called Advanced Mobile Robot Development. The class’s modest objectives, as described in the course catalogue, are to “detail, analyze and simulate a robotic lunar lander, field-test a lunar rover prototype, tackle enterprise challenges, and communicate mission progress through writing, photography and video.” The course is open to Carnegie Mellon students of any field at any level. Around the same time, Whittaker established Astrobotic Technology as a for-profit company with long-time space entrepreneur David Gump at the helm. Gump aggressively pursues corporate sponsorships and potential customers, whereas Whittaker contributes deep knowledge accumulated over more than 29 years of research at the Field Robotics Center. Among Astrobotic’s sponsors is Pittsburgh-based Alcoa, which has donated the aluminum required for the spacecraft that will carry the rover to the moon. Whittaker, an ex-marine and the son of a chemist and an explosives salesman, says that landing one of his team’s creations on the moon would represent the fulfillment of a career path that has seen his robots on land, water, underwater, underground, and in just about every environmental extreme here on Earth. Winning the moon doesn’t just mean the first prize; in his mind, Astrobotic won’t be successful until it meets every one of the bonus objectives as well. “If you haven’t done everything,” he says, “you haven’t done anything.” ROCKET SCIENCE whittaker’s vision for getting Astrobotic’s spacecraft and rover on the moon begins with the SpaceX Falcon 9 rocket. Established with the goal of dramatically reducing the cost of space access, SpaceX may be the key enabler of the Google Lunar X PRIZE competition. Whittaker believes that the SpaceX rocket will be the vehicle of choice for all the teams in the competition. “As far as I’m aware, every U.S. contender is targeting SpaceX,” he says. Even so, the cost of launch will be the single greatest expense for any team. Though less expensive than other rockets in its class, the published price of a Falcon 9 launch is still $54 million— more than twice the top prize. SpaceX’s competitors are reluctant to discuss their own launch arrangements, but it is clear that SpaceX has already upended the market with the single biggest commercial launch contract in history—a $492-million deal with Iridium, a satellite communications company. After Red Rover leaves Earth’s atmosphere atop its Falcon 9, the Astrobotic spacecraft-and-rover stack will jettison its protective nose fairing, and the rocket’s second-stage engine will push the spacecraft and rover on a course to the moon. The transit will take five days. Guidance, navigation and control software developed at Carnegie Mellon will keep the rocket on the right path. The software is a direct descendant of the code that enabled Tartan Racing to win the Urban Challenge. The computational challenges of autonomous driving and spacecraft piloting are not so different—the same kind of math solves both problems, which is why the software is so similar. The main difference, says Astrobotic team member and Ph.D. candidate Kevin Peterson, is the lack of GPS to guide the vehicle. Instead the craft will plot its trajectory to the moon by referencing stars, the moon and Earth. Once in orbit, the spacecraft and rover must descend to the moon’s surface. In 1969 astronaut Neil Armstrong piloted the lunar module from orbit to a specific location on the moon, while avoiding local hazards such as boulders and craters. But the 250,000-mile distance between our planet and its satellite imposes a time lag that precludes real-time control by a pilot on Earth, so the spacecraft’s software will have to accomplish autonomously what Armstrong did by hand. A primary descent engine will burn to slow the spacecraft down as it approaches the moon, while small thrusters will keep the vehicle stabilized. Touching down two days after lunar dawn, the lander will deploy two ramps (the second is a spare, in case a rock or crater obstructs the first). The bolts that hold the ramps folded against the ladder are rigged to break apart under intense heat. After the ramps fall from the spacecraft to the ground, the rover will roll down one of them to the moon’s surface, binocular eyes scanning the ground ahead. Moon dust is too slippery to permit an accurate reading of distance traveled based on how many times the rover’s wheels have turned. Instead the rover’s onboard computer will calculate distance by comparing the changing appearance of surface features as the robot moves. Radiation- hardened components will protect the computer from the unfiltered solar and cosmic radiation with which the airless moon is bombarded. Back in Pittsburgh, Astrobotic team members at mission control will work 24-hour shifts through the long lunar day, using a steady stream of low-resolution images to guide Red Rover to interesting features (including, it is hoped, an Apollo landing site). The rover will avoid hazards on the moon’s surface autonomously. It will beam high-definition video as blocks of encrypted data, at least one immediately after landing and one later in the mission to meet X PRIZE requirements. The rover will also send e-mail, tweets and Facebook posts. A major technical challenge for the team is making sure Red Rover survives the extremes of lunar day and night, each of which lasts two Earth weeks. During the two-week lunar night, the temperature at the moon’s surface where the team plans to land plummets from a daytime high above 248 degrees Fahrenheit to around −274 degrees F. Any components that contained traces of water, such as the batteries, would suffer irreparable damage as the water froze and expanded. The only rovers ever to have survived the extremes of day and night were the Soviet remote-controlled lunar rovers, called Lunokhods, in the 1970s. They relied on a radioactive polonium isotope to stay warm. But Astrobotic and other private companies competing for the X PRIZE do not have access to these tightly controlled materials. To protect Red Rover from the heat of the sun, carbon-fiber structures surrounding the battery cells conduct heat to the outer surface of the rover. At night, Red Rover will hibernate, and it will awaken with the sun to fire up nonaqueous lithium iron phosphate batteries rigorously tested by then Carnegie Mellon mechanical engineering undergraduate Charles Muñoz. That is the kind of innovation on the cheap that the X PRIZE is meant to inspire. Although Astrobotic stands a good chance of winning the Google Lunar X PRIZE race, it faces steep competition from India and Russia, which are jointly sponsoring a lunar rover, and from China, which is building a rover of its own that will use a radioisotope to stay powered up through the lunar night. If one of these gets to the moon first, the top prize drops to $15 million. COMPETITION whittaker’s team is also expecting strong competition from other X PRIZE participants. Mountain View, Calif.–based Moon Express, with backing from billionaire co-founder Naveen Jain and other wealthy individual investors, may be the best funded of the Google Lunar X PRIZE teams. It entered the fray only in 2010, three years after the contest was announced, so it is lagging behind Astrobotic. But it is overcoming its latecomer disadvantage with a preexisting spacecraft platform developed by NASA. Another contestant is Boulder, Colo.–based Next Giant Leap, headed by former U.S. Air Force pilot-turned-entrepreneur Michael Joyce. Joyce’s company has teamed up with Draper Laboratory (which designed the guidance, navigation and control systems that shepherded the Apollo spacecraft to the moon), a group at the Massachusetts Institute of Technology, and the space systems branch of Sierra Nevada Corporation. It is building a novel “hopping” spacecraft that obviates the need for a separate rover. The craft reignites the thrusters it uses for touchdown to lift off again and travel short distances to areas of interest. The idea seems workable but only if Joyce can raise the necessary funds. The Google Lunar X PRIZE organizers hope that if they build it, the market will come—that developing rovers and getting them on the moon will spur the growth of a new market. Astrobotic, for example, is offering room onboard its spacecraft and rover at the rate of $1.8 million and $2 million per kilogram (2.2 pounds), respectively, plus a $250,000 “integration fee.” For researchers such as University of Maryland physicist Douglas Currie, at least, a guaranteed spot for a fixed price on a commercial mission would be a boon. Currie and his colleagues want to place an array of laserranging retroreflectors on the moon to support measurements that would be 100 times more accurate than can be made with those left by the Apollo astronauts— if only missions become available on which to fly them. Perhaps the most enduring benefit of the X PRIZE will be to inspire the next generation of scientists and engineers. The race has lent an air of real-world excitement to Whittaker’s Advanced Mobile Robot Development course. During the final week of classes in April 2011, members of the Astrobotic structures team scurry about the 3,000-square-foot workshop of Carnegie Mellon’s Planetary Robotics Laboratory, which is entirely dedicated to the moon rover project. They are testing the design for fragmenting metal bolts, an alternative to typical explosive bolts, that unhinge the ramps from the spacecraft so that the rover can explore the lunar surface. Grad student Kanchi Nayaka and a group of undergrads prepare a high-speed video camera on a tripod to record the simulation. The students then throw a switch, and 17.9 seconds later the bolt breaks apart with a bang, and the ramp swings open and falls to the ground, ready for the rover to emerge. “Awesome!” Nayaka says. She steps back from the camera and shoots a grin at a visitor. “You must be good luck!” The most enduring benefit of the Google Lunar X PRIZE may be inspiring the next generation of scientists and engineers.

Scientific American, April 2012

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THE LIMITS OF BREATH HOLDING

It’s logical to think that the brain’s need for oxygen is what limits how long people can hold their breath. Logical, but not the whole story By Michael J. Parkes

 TAKE A DEEP BREATH and hold it. You are now engaging in a surprisingly mysterious activity. On average, we humans breathe automatically about 12 times per minute, and this respiratory cycle, along with the beating of our heart, is one of our two vital biological rhythms. The brain adjusts the cadence of breathing to our body’s needs without our conscious effort. Nevertheless, all of us also have the voluntary ability to deliberately hold our breath for short periods. This skill is advantageous when preventing water or dust from entering our lungs, when stabilizing our chests before muscular exertion and when extending how long we can speak without pause. We hold our breath so naturally and casually that it may come as a surprise to learn that fundamental understanding of this ability still eludes science. (Feel free to exhale now, if you haven’t already.) Consider one seemingly straightforward question: What determines how long we can hold our breath? Investigating the problem turns out to be quite difficult. Although all mammals can do it, nobody has found a way to persuade laboratory animals to hold their breath voluntarily for more than a few seconds. Consequently, voluntary breath holding can be studied only in humans. If the brain runs out of oxygen during a lengthy session, then unconsciousness, brain damage and death could quickly follow—dangers that would render many potentially informative experiments unethical. Indeed, some landmark studies from past decades are unrepeatable today because they would violate the safety guidelines for human subjects. Nevertheless, researchers have found ways to begin answering the questions surrounding breath holding. Beyond illuminating human physiology, their discoveries might eventually help save lives both in medicine and in law enforcement. DETERMINING THE BREAK POINT in 1959 physiologist Hermann Rahn of the University at Buffalo School of Medicine used a combination of unusual methods—slowing his metabolism, hyperventilating, filling his lungs with pure oxygen, and more—to hold his breath for almost 14 minutes. Similarly, Edward Schneider, a pioneer of breath-holding research at the Army Technical School of Aviation Medicine at Mitchel Field, N.Y., and, later, Wesleyan University, described a subject lasting for 15 minutes and 13 seconds under comparable conditions in the 1930s. Still, studies and daily experience suggest that most of us, after inflating our lungs maximally with room air, cannot hold that breath for more than about one minute. Why not longer? The lungs alone should contain enough oxygen to sustain us for about four minutes, yet few people can hold their breath for even close to that long without practice. In the same vein, carbon dioxide (the exhaled waste product made by cells as they consume food and oxygen) does not accumulate to toxic levels in the blood quickly enough to explain the one-minute limit. When immersed in water, people can hold their breath even longer. This extension may stem in part from increased motivation to avoid flooding the lungs with water (it is unclear whether humans possess the classical diving reflex of aquatic mammals and birds that lowers their metabolic rate during breath holding while submerged). But the principle remains true: breath-holding divers feel compelled to draw a breath well before they actually run out of oxygen.

As Schneider observed, “it is practically impossible for a man at sea level to voluntarily hold his breath until he becomes unconscious.” Unconsciousness might occasionally occur under unusual circumstances, such as in extreme diving competitions, and some anecdotes suggest rare cases in which children can hold their breath long enough to pass out, but laboratory studies confirm that normally we adult humans cannot do it. Long before too little oxygen or too much carbon dioxide can hurt the brain, something apparently brings us to the break point (as researchers call it) past which we cannot resist gasping for air. One logical, hypothetical explanation for the break point is that specialized sensors in the body observe physiological changes associated with breath holding and trigger a breath before the brain shuts down. Obvious candidates for such sensors would be ones that watched for lengthy expansions of the lungs and chest or that detected reduced levels of oxygen or elevated levels of carbon dioxide in the blood or the brain. Neither of those ideas appears to hold up, however. The involvement of volume sensors in the lungs appears to have been ruled out by various experiments conducted between the 1960s and the 1990s by Helen R. Harty and John H. Eisele, working independently in Abe Guz’s laboratory at Charing Cross Hospital in London, and by Patrick A. Flume, then at the University of North Carolina at Chapel Hill. Their experiments showed that neither lung-transplant patients, whose nerve connections between lungs and brain were severed, nor patients receiving complete spinal anesthesia, whose chest-muscle sensory receptors were blocked, could hold their breath for abnormally long periods. (It is significant that those anesthesia experiments did not affect the diaphragm muscle, however, for reasons that will become apparent.) Research also seems to exclude the involvement of all the known chemical sensors (chemoreceptors) for oxygen and carbon dioxide. In humans, the only known sensors detecting low blood oxygen levels are in the carotid arteries just underneath the angle of the jaw, which supply blood to the brain. The chemoreceptors detecting raised carbon dioxide levels are in the carotid arteries and in the brain stem, which controls regular breathing and the other autonomic (involuntary) functions. If the oxygen chemoreceptors caused the urgent sensation of break point, then without their feedback, people ought to be able to hold their breath until rendered unconscious. Experiments in Karlman Wasserman’s laboratory at the University of California, Los Angeles, have shown, however, that patients still cannot do so if the nerve connections between chemoreceptors in their carotid arteries and the brain stem are severed. Moreover, if reduced oxygen or elevated carbon dioxide levels alone dictated the break point, then beyond some threshold levels, breath holding should be impossible. Yet numerous studies have shown this not to be the case. It would also be true that after the gas levels triggered a break point, breath holding would remain impossible until the arterial oxygen and carbon dioxide levels returned to normal. But that prediction is not borne out, either, as researchers have casually observed since the early 1900s. In 1954 Ward S. Fowler of the Mayo Clinic described formally how after maximum breath holding, subjects could immediately do it a second time if they inhaled only an asphyxiating gas—and even a third time, despite their blood gas levels becoming progressively worse. Further work has verified that this remarkable repeated breath-holding capability is independent of the number or vol

ume of inhalations of the asphyxiating gas. Indeed, in 1974 John R. Rigg and Moran Campbell, both at McMaster University in Ontario, demonstrated that it persists even when the subjects merely attempt to exhale and inhale with their airway closed. Taken together, all these experiments involving repeated breath-holding maneuvers suggest that the need to draw a breath somehow relates to the muscular act itself and not directly to its gas-exchange functions. When the chest is greatly inflated, its natural tendency is to recoil unless the inspiratory muscles of breathing hold it in the inflated state. So researchers of the break point began to look for answers in the body’s neurological and mechanical controls over these inspiratory breathing muscles. As part of that work, they also wanted to learn whether breath holding involves a voluntary halt of the automatic breathing rhythm that drives these muscles or the prevention of the breathing muscles from expressing this automatic rhythm. UNREPEATABLE EXPERIMENTS the normal rhythm of our breathing can be said to begin when the brain stem sends impulses down our two phrenic nerves to the bowl-shaped diaphragm muscle underneath the lungs, telling it to contract and inflate the lungs. When the impulses stop, the diaphragm relaxes and the lungs deflate. In other words, some rhythmic pattern of neural activity—a central respiratory rhythm—mirrors the cycle of our breaths. In humans it is still technically and ethically impossible to measure this central rhythm directly from the phrenic nerves or from the brain stem. Investigators have devised ways to record the central respiratory rhythm indirectly, however: by monitoring instead the electrical activity in the diaphragm muscle, the pressure in the airway or other changes in the autonomic nervous system, such as the heartbeat rhythm (known as respiratory sinus arrhythmia). Working from such indirect measurements, Emilio Agostoni of the University of Milan in Italy showed in 1963 that he could detect a central respiratory rhythm in human subjects holding their breath well before they reached break point. In related experiments at the University of Birmingham in England in 2003 and 2004, graduate student Hannah E. Cooper, anesthetist Thomas H. Clutton-Brock and I used respiratory sinus arrhythmia to show that the central respiratory rhythm never stops: it persists throughout breath holding. Breath holding must therefore involve suppressing the diaphragm’s expression of this rhythm, possibly through a voluntary, continuous contraction of that muscle. (Various experiments seem to have ruled out the involvement of other muscles and structures involved in normal breathing.) Break point may similarly depend on sensory feedback to the brain from the diaphragm—reflecting, for example, how stretched or unusually overworked it may be. If so, then paralyzing the diaphragm to eliminate its sensory feedback to the brain ought to allow subjects to prolong their breath holding greatly if not indefinitely. Such was the expectation in one of the most alarming breath-holding experiments ever, which Campbell performed at Hammersmith Hospital in London in the late 1960s. Two healthy, conscious volunteers consented to have all their skeletal muscles temporarily paralyzed with intravenous curare—except for one forearm, with which they could signal their wishes. The subjects were kept alive with a mechanical ventilator; breath holding was simulated by switching it off, and the subjects indicated their break point by signaling when they wanted the ventilator restarted. The result was astonishing. Both volunteers were happy to leave the ventilator switched off for at least four minutes, at which point the supervising anesthetist intervened because their blood carbon dioxide levels had risen perilously. After the effects of the curare had worn off, both subjects reported feeling no distressing symptoms of suffocation or discomfort. For obvious reasons, such a daring experiment has rarely been repeated. Some others have tried and failed to replicate Campbell’s findings, but their courageous volunteers reached break point after such a short duration that their carbon dioxide levels barely rose above normal. Those observations suggest that the subjects might have chosen to end the tests early, possibly because of discomfort from the air tubes holding open the glottis (a modern safety requirement not present in Campbell’s experiment) and because of their greater awareness of the lifethreatening risk. Nevertheless, some equally remarkable experiments by Mark I. M. Noble, working in Guz’s laboratory at Charing Cross Hospital in the 1970s, seem to confirm that diaphragm paralysis prolongs breath-holding duration. Instead of total body paralysis, Noble and his colleagues used the much less lifethreatening maneuver of paralyzing the diaphragm alone by anesthetizing only the two phrenic nerves. Doing so doubled subjects’ average breath-holding duration and reduced the usual uncomfortable sensations that accompany breath holding. CURRENT BEST EXPLANATION the balance of evidence thus favors the speculation that a voluntary, lengthy contraction of the diaphragm holds the breath by keeping the chest inflated. The break point may depend very much on stimuli that reach the brain from the diaphragm in this unusual contracted state. During such a lengthy contraction, the brain might subconsciously perceive the unusual signals from the diaphragm as vaguely uncomfortable at first but eventually as intolerable, causing the break point. The automatic rhythm then regains control. This hypothesis is not fully fleshed out, but it fits nicely both with Fowler’s observations (that any release of breath holding, necessarily by relaxing the diaphragm, enabled another one) and with the effects of lung inflation and blood-gas manipulation on breath-holding duration. Relaxing the diaphragm even a bit and exhaling slightly would delay break point by relieving the signals from the stretch sensors in the diaphragm. Raising the oxygen level and lowering the carbon dioxide level in the blood would also extend breath-holding capability by reducing biochemical indicators of fatigue in the diaphragm. Anything that prevents the brain from monitoring such information—for example, by blocking the nerves between the diaphragm and the brain—will extend duration. The tolerance of the brain to such unpleasant signals will also depend on your mood, motivation and ability to be distracted by, say, mental arithmetic. This hypothesis is only the simplest unifying explanation for the experimental observations. Some of these experiments used too few subjects to be the basis for reliable generalizations, and ethical permission to repeat them may never be granted. Key pieces of the jigsaw puzzle may still be missing. Moreover, a puzzle piece that does not yet quite fit comes from another of Noble and Guz’s dramatic (and now ethically unrepeatable) breath-holding experiments. They tripled the duration of breath holding in three healthy subjects by anesthetizing their two sets of cranial nerves (the vagus nerves, which go from the brain to organs in the chest and abdomen, and the glossopharyngeal nerves, which go to the glottis, larynx and other parts of the throat). This result would appear to have been achieved without affecting the diaphragm, except that it is also possible that the vagus nerves, too, carry some signals from the diaphragm. It seems less likely that the larynx itself contains a muscle involved in breath holding: in 1993 when surgeon Martyn Mendelsohn of Sydney, Australia, viewed the glottis (via a camera inserted through a nostril), the glottis often remained open throughout breath holding. This observation, too, seems to support the conjecture that the diaphragm’s role is key. SAVING LIVES better understanding of what limits people’s ability to hold their breath has practical uses in medicine. As part of the treatment for breast cancer, for instance, patients receive radiation therapy, during which the goal is to lethally dose the entire tumor without damaging the healthy tissues all around it. Doing so requires minutes of radiation exposure, during which a patient must try to keep her breast motionless. Because breath holding for so long is impractical, current practice uses short bursts of radiation timed to fall between a patient’s breaths, when her chest is moving least. Yet with each breath, the breast moves and may not necessarily return to exactly the same position. Medical physicist Stuart Green, clinical oncologist Andrea Stevens, anesthetist Clutton-Brock and I are now starting experiments funded by University Hospital Birmingham Charities to test whether it would be feasible to prolong breath holding sufficiently to aid radiotherapy treatment. A practical understanding of breath holding might also be of value to law-enforcement personnel when they are forcibly restraining suspects. Every year around the world some people under restraint may die accidentally. Raising the metabolic rate, compressing the chest, lowering the blood oxygen level and raising the blood carbon dioxide level all shorten the duration of a person’s breath holding. So someone who is angry, has been fighting or is being forcibly held down may well need to draw a breath earlier than someone who is relaxed. In 2000 Andrew R. Cummin and his team at Charing Cross Hospital studied what happened after eight healthy subjects breathed out maximally and held their breath after cycling moderately for one minute: the duration of their maximum breath holding plummeted to 15 seconds, the average amount of oxygen in their blood fell dramatically and two of them developed irregular heartbeats. Consequently, the researchers concluded that the “cessation of breathing for short periods during vigorous restraint . . . may account for unexplained deaths in these circumstances.” Law-enforcement authorities have carefully compiled guidelines for the use of forcible restraint; they should be observed scrupulously. Such investigations of breath holding open windows into vital aspects of human physiology. Clearly, more groundbreaking discoveries, particularly about the diaphragm itself, remain ahead—which leaves some of us breathless in anticipation.

Scientific American, April 2012

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Healing Kansas

 

Better health requires improved education, more access to nutritious food and greater economic opportunities, new county rankings show As mayor of Kansas City, Kan., Joe Reardon is justifiably proud of the University of Kansas Medical Center, which has trained several generations of physicians and nurses for more than 100 years. After all, the medical center is consistently rated as the best hospital and treatment center in the state, according to a popular ranking of health institutions. So when Mayor Reardon—who heads the government of both the city and Wyandotte County, in which it sits—first learned that Wyandotte had come in dead last among the state’s counties in a rigorous analysis of health measurements in 2009, he was shocked. “We have great access to excellent health care in a state where some counties have essentially no access,” Mayor Reardon says. “And we’re ranked last out of 105 counties? My first reaction was, ‘How could this be?’” The answer, Mayor Reardon discovered as he delved into the statistics behind the claim, is that proximity to fine hospitals and first-rate doctors is only one of many factors—and not always the most important—determining how long people live and how vulnerable they are to serious illness. Evidence collected by public health experts over the past few decades repeatedly shows that less obvious forces, including proper diet and exercise, higher levels of education, good jobs, greater neighborhood safety, and underlying support from family and friends, provide a powerful, and often unappreciated, boost to a community’s health and well-being. By the same token, studies demonstrate, a poor showing in any of these areas can sink the health of individuals or of communities—even if they have access to topflight medical facilities. The goal of the County Health Rankings project, which has given Wyandotte County low marks for health but high praise for its commitmennt to change, is to bring these hidden health factors to light and thereby help elected officials, civic leaders and community groups take concrete steps that can improve the health of local residents. The initiative originated at the University of Wisconsin– Madison, covering solely that state in 2003. A similar project began in Kansas in 2009, and in 2010 the Robert Wood Johnson Foundation in Princeton, N.J., provided funding so that the University of Wisconsin could expand its investigation to include within-state comparisons of counties in all 50 states. Among the biggest lapses identified in Wyandotte County, for example, were much higher than average rates of smoking and obesity, lower than average rates of high school graduation, a distressing number of babies who weigh too little at birth, and a relative scarcity of fresh fruits and vegetables in grocery stores compared with the rest of the state. Mayor Reardon says these measurements have already transformed his approach to budget priorities. Changes include earmarking money for the addition of mentoring programs for high school students, new parks and sidewalks, and the opening of more and better supermarkets and community gardens in impoverished neighborhoods. And that is just the start, Mayor Reardon says. “The measure of our success as a city is not just how many jobs we create but also the health of our citizens.” He believes that potential employers who want to stay competitive in today’s global marketplace are more likely to settle in communities where workers are both highly skilled and relatively healthy. PUBLIC HEALTH STRATEGY HAS DEEP ROOTS The notion that government officials can use public health statistics to improve policy decisions is not new. In 1854 physician John Snow, one of the founders of modern epidemiology, traced a cholera outbreak in the overcrowded London neighborhood of Soho to a contaminated public water pump by noting how many cases of illness clustered around the pump. (The pump was later found to be too close to a leaking cesspool.) Snow convinced officials to disable the pump, which helped to stop the spread of disease. Today’s health statisticians still search for instructive patterns of behavior and illness in communities, although they have moved beyond simply tracking infectious disease rates and deaths. Now adays, says Julie Willems Van Dijk, a researcher at the University of Wisconsin Population Health Institute who helps county leaders figure out what to do with the data, public health officials also monitor quality of life and trends in chronic, noncommunicative disorders, such as depression, diabetes and heart disease. The trick for researchers, Willems Van Dijk says, is to sift information from broad studies of large populations to identify behaviors and other influences on health that can be modified. The next step is to see how those factors play out at the level of the city, county and town, where many of the policy decisions that most directly affect people’s health are often made. Individual cities started enforcing smoking bans in restaurants, Willems Van Dijk notes, after studies showed that secondhand smoke increased the number of heart attacks and cases of asthma in nonsmokers. The County Health Rankings project, now updated annually, is an attempt to provide reliable health statistics on a scale and in a format that public officials can use to take action, such as altering zoning rules to allow for beneficial placement of grocery stores, bike paths and parks. FOUR BROAD CATEGORIES In comparing the counties within each state, Willem Van Dijk and her colleagues at the University of Wisconsin gather no new data. Instead they base their ratings on public information scoured nationwide from various sources, including the National Center for Health Statistics, the FBI and the U.S. Census. Their aim is to identify robust, reliable indicators that are measured the same way from county to county within each state for four broad categories—behavior, clinical care, socioeconomic status and physical environment— that research shows shape health. Within these groupings, some of the most influential factors—such as smoking (behavior)— come as no surprise. Others include education level attained by most of the population (socioeconomic status), the relative number of sexually transmitted diseases diagnosed each year (behavior), and the number of car crashes related to drunk driving (behavior). Researchers analyze a host of patterns in the data to help community leaders spot where improvements are most needed. For example, Wyandotte County scored particularly low on education in 2011. Part of the reason for that result is that just 60 percent of its ninth graders graduated from high school within four years, and only 42 percent of adult residents aged 25 to 44 had spent some time in college. Mayor Reardon hopes the high school internship and mentoring programs he has helped establish within the city government and within some of the county’s high-technology firms will help turn around those low scores on education. Students need to see the link between college and a good job, he says, and to imagine themselves following that path. NOT EVERYONE BELIEVES Not every Kansas official has responded as enthusiastically as Mayor Reardon has. At a 2009 public meeting in Shawnee County (home to the state capitol, Topeka), then County Commissioner Vic Miller dismissed Shawnee’s low health ranking (78 out of 105) as misleading. “Frankly, I can’t imagine what argument you’re going to promote that dropout rates in schools relate to public health,” Miller was quoted as saying in the Topeka Capital-Journal. Willems Van Dijk says that Miller’s skepticism is understandable, but the evidence that socioeconomic factors like education play a major role in health is solid and growing. For example, high school dropouts tend to die earlier than graduates. Further, their children are more likely to be born prematurely, robbing another generation of a healthy start. Every year of additional education improves those outcomes. “Research is now showing that many health effects once attributed to racial differences are actually tied to educational and economic disparities,” she says. WHEN POLITICAL AND HEALTH PRIORITIES COLLIDE No one expects a county’s overall ranking to improve overnight. “Where you are on the curve isn’t as important as which direction you’re moving,” Willems Van Dijk says. Wyandotte County was rated at or near the bottom of Kansas rankings for three years in a row and is likely to be there again when the state’s latest numbers are released this spring. Yet Mayor Reardon is hopeful that the measures he is taking will ultimately shift the course. County planners must now consider the needs of pedestrians and bicyclists as well as drivers when designing road improvements, he notes. And a newly remodeled supermarket has doubled the amount of fresh fruits and vegetables that are available downtown. “There are a lot of polarizing issues in Kansas City,” he says, “but I’ve been pleasantly surprised to see that doing all we can to improve the health of our community isn’t one of them.” That mapmaking visionary of epidemiology, John Snow, would be proud. 

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