NARRATOR: In a time when there were few unmapped regions left on Earth, some of the last places for humans to set foot were the tops of the tallest mountains. Teams from several nations competed to be first. After many tried and died, by the middle of the 20th century, the most famous peak, Everest, was conquered. But on the other side of the world, in Alaska, close to the Arctic Circle, there is a mountain as challenging to climb as Everest. For on its slopes lurks an invisible killer.
DR. HOWARD DONNER (Wilderness Medicine Specialist): Roger, are you ready for us?
NARRATOR: Denali: it's the highest mountain in North America, and with a wind chill temperature that can drop to minus 148 degrees, it is perhaps the coldest mountain in the world.
DR. PETER HACKETT (University of Colorado School of Medicine): The cold is extreme. There is no colder mountain with these kinds of numbers on it.
NARRATOR: Today, a thousand climbers a year come to Denali, not for national honor but for personal achievement and sport. But that sport can be deadly.
COLBY COOMBS (Alaska Mountaineering School): I've been in an accident where my best friend has died and I'm tied to him.
NARRATOR: This season, the mountain will claim another climber as a victim. But a team of world class athletes and scientists will try to solve the mystery of why extreme cold and high altitude kill, pitting themselves against the mountain and putting their own lives at risk, as they attempt the rugged climb to the summit of Denali. Up next on NOVA, Deadly Ascent.
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NARRATOR: Above the distant horizon, hidden in a land of ice and snow, a granite giant lies shrouded in sheets of ancient glaciers. At 20,320 feet, the highest peak in North America soars above the clouds. In 1896, it was named Mount McKinley, but before then, and today, it's known by its Native American name, Denali, "the high one."
Every year over a thousand climbers come from all over the world to pit themselves against the mountain. Half succeed and reach the summit, but the other half fail, and, on Denali, failure can mean death.
PETER HACKETT: Denali is the most underestimated mountain on Earth, because you can get by with perfectly clear weather. The climbing isn't difficult, and you can go back home and tell your friends what an easy cakewalk it is up Denali. Your friends will come up, hoping for the same cakewalk, and get killed.
NARRATOR: For the next three months of the climbing season, Peter Hackett will serve as doctor at a medical rescue camp. Deep within the Alaska wilderness, this glacier, 7,000 feet above sea level is where mountaineers are flown to begin their climb. Chances are, three will die.
DARYL: Give me an assessment. This person needs to be evacuated right away.
NARRATOR: Hackett's work begins immediately.
PETER HACKETT: He's not vomiting any blood, is that correct?
NARRATOR: A climber has collapsed high in the mountain. He's helicoptered down to Medical Camp for evaluation.
DARYL: The patient will be loaded in a sitting position in the helicopter. Over.
PETER HACKETT: I came to Denali almost 20 years ago now. At that time, there wasn't that much known about high altitude illness, and it was hard to study in human volunteers, because you couldn't ethically take them to a mountain and allow them to get very ill.
NARRATOR: Denali, is one of the few places that doctors can study humans in extreme environments.
PETER HACKETT: We'll get you inside and get sitting down and get you on oxygen.
NARRATOR: This climber was attacked by a mysterious disease, making it hard for him to breathe. National Guardsmen arrive in a larger helicopter to evacuate him to a hospital in Anchorage.
PETER HACKETT: Denali is the perfect place to find climbers who are here of their own volition, who needed help when they got in trouble and would also serve as research subjects.
He got a bronchial obstruction up at 14,000. It nearly killed him.
NARRATOR: Why are climbers on Denali becoming sick and dying? Hackett's mission is to find out.
To assist Hackett is a team of world class athletes and scientists. Colby Coombs, director of the Alaska Mountaineering School will lead the expedition. He's successfully climbed to the summit more than a dozen times and is no stranger to the hazards they'll be facing.
COLBY COOMBS: There's cold, there's altitude, there's glacier travel, there's winter camping. There's all these things combined.
NARRATOR: Caitlin Palmer is a veteran Denali guide.
CAITLIN PALMER (Alaska Mountaineering School): I've always been a lover of the mountains and a mountain person.
NARRATOR: She's the team's expedition coordinator. Caitlin and Colby are husband and wife.
JOHN GRUNSFELD (NASA Chief Scientist): Up at the summit, it looks like their winds are blowing maybe 15 knots or so.
NARRATOR: John Grunsfeld is a veteran of extreme environments; he's an astronaut.
JOHN GRUNSFELD: Space is someplace where humans don't belong. We weren't born there, we didn't evolve to live there, so it's a very new area for people, something akin to mountaineering.
NARRATOR: On Earth, Grunsfeld has never climbed higher than 17,000 feet, but now Colby, Caitlin and Grunsfeld will climb to over 20,000 feet, the summit of Denali. Over the next four weeks, on the tallest and coldest mountain in North America, the team will push the limits of human survival. For, not only are they assisting Hackett in his investigation, they are also his human guinea pigs.
Doctor Howard Donner, a medical consultant for NASA and the U.S. military, is recruited to help monitor the team.
HOWARD DONNER: Have you taken these at Johnson Space Center?
JOHN GRUNSFELD: I haven't. We've used them on a number of space shuttle missions, and I've had the pleasure of not taking one yet.
NARRATOR: Donner provides some new technology that is crucial to the investigation, a thermometer pill.
HOWARD DONNER: And after you swallow it, we should be able to receive your G.I. tract temperature, which, essentially, would be your core temperature.
NARRATOR: The thermo pill, designed by NASA, contains a battery, heat-sensitive crystal, and transmitter that sends core body temperature readings to a handheld receiver.
HOWARD DONNER: So I'm just pushing the receive button trying to get a reading on that pill, and now it's coming up.
NARRATOR: Before using the radio pill on Denali, Donner took it for a test in Natick, Massachusetts, where the Army runs the largest wind-generating cold chamber in the U.S. Donner tries it on a human subject named Pete Athans, an elite climber known as "Mr. Everest."
HOWARD DONNER: I think it would be interesting to have Pete strip off some of his clothing to take a look at what happens to human bodies subjected to this kind of cold. So, Pete, if you would...
PETE ATHANS: Having been in this chamber for a little while, it's definitely getting a little frozen up here.
HOWARD DONNER: The beauty of these swallowable pills are you're able to continuously monitor a climber's core temperature.
NARRATOR: What's called the body's core is made up of three essential organs: the brain, the heart and the lungs. When the brain senses that the body is cold, it sends a message to slow blood flow to the extremities, maintaining precious heat around the heart and lungs. If the body's core temperature—normally about 98.2—drops just 3 degrees, a condition called hypothermia begins. Soon vital organs start to shut down, a major step toward freezing to death.
HOWARD DONNER: How're you doing, Pete? You don't look real happy.
PETE ATHANS: I'm starting to feel a little muscular rigidity. It's definitely getting a little harder to speak, actually. Yeah, I think I'm about ready to head for the door, here. My hands are turning into bricks. So I'm going to take off.
HOWARD DONNER: We can't do that on the mountain, you know.
PETE ATHANS: No, we can't.
NARRATOR: This expedition to the summit of Denali is the first time that core temperatures will be monitored.
JOHN GRUNSFELD: Okay, Caitlin, you ready?
CAITLIN PALMER: I am.
JOHN GRUNSFELD: Here's your personalized ingestible temperature sensor.
CAITLIN PALMER: It's awfully big.
NARRATOR: The point of tracking the climbers' core temperatures, is to solve a long-standing medical mystery: why extreme cold and high altitude are such a lethal combination.
CAITLIN PALMER: Down she goes.
NARRATOR: In the light of the midnight sun, Hackett and the summit team—Colby, Caitlin and Grunsfeld—start their ascent out of base camp at 7,000 feet. Their plan is to hike Denali's West Buttress. They'll be stopping at camps at 11,000, 14,000 and 17,000 feet. From 17,000 High Camp, they'll make their final assault on the summit. It's a total of 15 and a half miles.
The time it will take to reach each stage of their climb depends on their strength and speed, trail conditions and weather. And on Denali, weather can change in an instant.
Blinding snow reduces their visibility to just a few feet of icy trail. Winds can be like snowy hurricanes and within minutes, bury climbers. Blizzards combined with temperatures of 70 below, can actually flash freeze any exposed skin.
Throughout the mountain are grim reminders of what can happen when things go wrong. More than 30 bodies of victims remain frozen on the slopes of Denali where the climbers collapsed and died.
After hiking all night, battling the arctic elements, the team reaches camp at 11,000 feet. Though this is just the first stage of their climb, the expedition is facing a true survival situation. The team scrambles to escape the freezing storm. Caitlin fires up stoves to melt snow into drinking water.
CAITLIN PALMER: We make a lot of water out here, it's constant water, 'cause we need to drink tons and tons to keep healthy and acclimatized.
NARRATOR: The formula for survival in extreme cold is simple: eat, drink and ensure the body retains more heat than it loses. Essential is thermal clothing and shelter.
CAITLIN PALMER: These guys are just finishing up putting the anchors in, and I'm trying to keep this center pole here.
NARRATOR: This temporary shelter, with the walls of an igloo and a roof of wind resistant nylon will protect the team from the raging storm outside.
CAITLIN PALMER: It works really well. As you can see we're pretty well sealed in here. We've got the entrance way, of course, that's going to give us some draft, and we do need air flow, since we have 6 stoves running. It's a fantastic shelter. We'll really appreciate it later this afternoon.
NARRATOR: One of the first attempts to reach the summit of Denali was in 1912. Three months of dog sledding, over hundreds of miles, led a group of pioneers to the mountain. Within 300 feet of the summit, a blizzard forced their retreat.
A year later, Walter Harper, a native Alaskan Indian became the first known person to set foot on the roof of North America. Since then, scores of men and women have blazed dozens of trails to the summit: The Ridge of No Return, Isis Face and Catacomb Ridge.
All these trails involve elements of danger, and every path to the summit can be deadly. Forty five percent of all deaths on Denali are caused by climbing falls. To avoid becoming one of those statistics, members of the climbing team practice saving themselves by using an essential climbing tool, an ice axe.
COLBY COOMBS: In the event of a fall and someone on your rope team yells, "Falling," it's got to be an instinctive, immediate reaction. Thumb under the adz, fingers over the top, other hand down near the spike. It's a technique that you need to practice every year if you spend time on snowy slopes. It's amazing how quickly you'll accelerate if you fall.
NARRATOR: But sliding down slopes and falling off cliffs are not the only dangers. Denali is covered by glaciers rife with crevasses, fractures that can be thousands of feet deep.
COLBY COOMBS: That's tied in to the clip-in point there. This anchor we're going to use for lowering and for hauling. Caitlin, let's make sure that you have the gear required to ascend out of the crevasse.
NARRATOR: Climbers who fall into a crevasse and are lucky enough, to survive...
COLBY COOMBS: You've got 'biners locked, knots dressed?
NARRATOR: ...must be prepared to climb out.
COLBY COOMBS: We've got the climbing rope. We've got the belay line.
NARRATOR: To practice their survival skills, the team lowers Caitlin into the abyss.
CAITLIN PALMER: That's good...even a little bit more.
When you fall into a crevasse, it's instantly cold, and you plunge into a world without much sunlight.
And there's ice all around you—it's very chilly—and you get to the business of getting yourself out.
NARRATOR: Caitlin's core body temperature has dropped slightly below normal. So to maintain precious heat around her core organs, the muscles surrounding the blood vessels in her arms and legs will soon begin to constrict, preventing warm blood from flowing away from the core.
This involuntary response is called vasoconstriction. Although it saves vital organs, it would make it impossible for Caitlin to use the muscles in her hands and feet.
JOHN GRUNSFELD: Here we go, coming up.
NARRATOR: Without an expedition team to haul them to safety, climbers who fall into crevasses can succumb to the cold within three hours.
Once out of the crevasse and into the sunlight, Caitlin's core temperature goes back to normal.
Denali may be known for its cold, but the white heat of the midnight sun reflecting off the glacier can feel like an oven. Add to that a heavy pack and a steep uphill climb and the climbers' core temperatures begin to rise.
PETER HACKETT: Humans are homeotherms, which means that they maintain a stable body temperature around a set point, and that set point doesn't change when we come up here. And so we have to do things to maintain that core temperature or we get very uncomfortable.
NARRATOR: Even the slightest rise in core body temperature can affect judgment, producing a lightheadedness that resembles being drunk. When climbers' core temperature rises above 101 degrees, they enter the beginning stages of hyperthermia.
JOHN GRUNSFELD: We've been hiking for about four hours. I've still got one of those thermal pills, somewhere. It's reading at about 100-100.5 degrees, so it's toasty warm inside.
NARRATOR: Here on the coldest mountain on Earth, the thermo pill records that the team's core temperatures are rising. But while Caitlin's temperature rises only slightly, Grunsfeld's is heating up to what could be a dangerously high level.
PETER HACKETT: They can generate a lot of heat, as any athlete would or any person who is exercising heavily, even in a cold environment.
NARRATOR: By tracking Caitlin and Grunsfeld's core body temperatures, Hackett hopes to prevent them from falling victim to Denali's lethal high altitude cold.
CAITLIN PALMER: Slow and steady coming around a windy corner here, keeping the ropes tight 'cause there's lots of little cracks around here. But we're doing very well. It's a beautiful afternoon, quite warm, in fact.
JOHN GRUNSFELD: Starting to get into the thin air just a little bit—lot of people here—last push before 14.
NARRATOR: The team is pushing hard to reach 14,000 feet. For Hackett, it is a return to the highest medical research lab in the United States, which he set up 18 years ago.
HOWARD DONNER: How does it feel to be at 14 after all these years?
PETER HACKETT: You know, there's a familiarity, definitely, but I would never call this place home.
NARRATOR: Howard Donner arrived here two days ago.
HOWARD DONNER: One thing I'm in touch with on arriving here at 14,000 feet, is the tension. The mountain is spectacular, it's awesome. Right now the weather is good, but there is this underlying tension that nobody knows exactly what's going to happen. And statistically speaking, there are more than 100 people in this camp right now. Odds are, one are two are going to die, and a few are going to need to be rescued.
NARRATOR: Going from 11- to 14,000 feet, the climbers are now half way to the summit. But the higher they climb, the less oxygen there is to breathe. This lack of oxygen, called hypoxia, can produce headaches, breathlessness and nausea, a condition known to climbers as acute mountain sickness, or A.M.S.
Two months earlier, in the heart of the Rocky Mountains, Peter Hackett conducted a unique altitude study to combat A.M.S.
PETER HACKETT: Now you all came up here pretty fast, and that was the idea.
NARRATOR: Volunteers from Mesa State College are traveling to 14,000 feet to spend the night at the top of Pike's Peak. Without a chance to acclimate, they're likely to feel sick.
PETER HACKETT: Headache usually comes first, and then a couple of you might throw up. How have you felt since you arrived?
NARRATOR: Hackett gives half the group an ancient herbal remedy called ginkgo; the other half gets a placebo. Hackett is experimenting to see if ginkgo can prevent the debilitating effects of altitude sickness.
VOLUNTEERS 1&2: We're from sea level so we're like, we're from San Diego, big drastic change, and so we're going to see how it goes.
We're praying I don't get sick.
NARRATOR: At first, most of the students seem oblivious to the altitude. But at 14,000 feet there's less than two thirds as much oxygen as there is at sea level. As the night goes on, several of Hackett's experimental subjects begin to feel the effects of A.M.S.
PETER HACKETT: Janell just spent a pretty uncomfortable night up here at Pike's Peak. She got altitude sickness pretty early on after she arrived—within four hours or so—but it didn't really progress much. Here let's put this mask on you.
NARRATOR: At sea level, human blood is nearly a hundred percent saturated with oxygen. Janell's is around 80 percent, and the result is nausea and dizziness.
PETER HACKETT: You'll be feeling better here pretty quickly. Thanks for hanging in there with us.
JANELL (A.M.S. STUDY VOLUNTEER): Yeah.
NARRATOR: Oxygen can reverse the symptoms, But Hackett's study may lead to a way to prevent them. Sixty eight percent of the subjects who received the placebo got sick, while only 33 percent who took ginkgo did.
Ginkgo appears to reduce the incidence of mountain sickness by more than half.
VOLUNTEER 2: Thank god for the ginkgo. I think I had it.
NARRATOR: Back at 14,000 feet on Denali, after acclimating to the altitude with a good night's rest, the expedition team begins the next stage of the climb. Hackett and Donner will stay at Medical Camp and continue to monitor Colby, Caitlin and Grunsfeld on their long trek up to High Camp.
They ascend the headwall, a steep cliff gouged out by an ancient glacier. A 55 degree slope of snow and ice, the headwall is the most technical and one of the most difficult parts of the route.
Their loads are heavy, packed with food for 10 days, in the event that they'll need to wait for good weather for a summit attempt. They know conditions on Denali can change in an instant.
JOHN GRUNSFELD: In order to get up here, we had to climb up a relatively steep headwall, probably the steepest part of the whole route. We clipped into fixed lines just as protection, so that we could get up in case one of us fell. I have to breathe a lot to be able to talk like this.
NARRATOR: Amazingly, in the few moments that Grunsfeld stops to talk, his core temperature drops from a high of 103 degrees—the danger zone for hyperthermia—to 95.5, the temperature where hypothermia begins.
PETER HACKETT: He's an engine that's revved up and going producing all this heat. As soon as the engine's turned off, which basically happens when he stops, the heat production stops but the heat loss doesn't stop. He's still in a cold environment; heat loss continues, core temperature plummets.
NARRATOR: Humans can survive in Denali's extreme cold for only so long. They either need to move to generate heat or find shelter. And in the arctic climate of Denali, sometimes frozen snow is the best insulation available.
COLBY COOMBS: You've kind of just got to slither your way in. A cave is an emergency shelter; a cave offers an incredible amount of protection from the elements. It's completely windproof. And if they're done correctly, snow is a great insulator, and it'll actually retain a lot of the heat from your stoves and from your body.
NARRATOR: At 16,000 feet, severe weather forces the team to take refuge in a snow cave left over from a previous expedition. But others are not so lucky. Back at Medical Camp, at 14,000 feet, Donner receives a distress call from a climber caught in the storm.
ROGER ROBINSON (National Park Service): So, Howard? We'll put it down right through here like this.
NARRATOR: Rescue workers construct an emergency landing zone for a helicopter.
HOWARD DONNER: There's a patient that took a pretty bad fall up on Denali Pass. We actually don't know how far he fell yet. He's unable to walk. I mean, that's clear.
NARRATOR: This may be the only chance to get him out.
ROGER ROBINSON: The big Army helicopter, with a high altitude rescue team, is going to land. What they need is a fairly marked out approach. And they like to land kind of like...a plane kind of goes sliding along, and they've got these huge skis that they land on.
NARRATOR: Special Forces of the Air National Guard, based in Anchorage, are mobilized to evacuate the sick climber.
SCHUMAN: Any type of environment we have to be prepared for.
LOOMIS: We're parachutists, divers, climbers, paramedics.
SCHUMAN: We're the only American force that's dedicated only to rescue. We rescue combat and civilian.
LOOMIS: We go behind enemy lines to rescue pilots shot down in a conflict.
NARRATOR: Climbing injuries have many causes including altitude sickness, extreme weather, bad judgment, even bad luck. Whatever the cause, rescuers often put their own lives at risk.
HOWARD DONNER: Roger, are you ready for us?
The patient, although stable at this point, is a somewhat older guy and has a lot of injuries. Our priority is to get the patient out of here.
NARRATOR: The Special Forces lift him out of the cold, and fly him down to an Emergency Room in Anchorage.
PETER HACKETT: It's tricky with medical problems on this mountain. He would have died if they hadn't gone up and rescued him. He would have died from exposure, because his group wasn't capable of getting him off the rope, making a shelter, putting him in a sleeping bag, making water. They just didn't have it together to do that.
NARRATOR: Secure in their snow cave at 16,000 feet, Caitlin and Grunsfeld are maintaining normal core temperatures, as measured by the thermo pill. But other climbers, in the grips of "summit fever," foolishly push on through the storm.
PETER HACKETT: There are days when people shouldn't move. A lot of the frostbite is because people move on days when they really ought to be staying in their tents.
CLIMBER 1: All 10 fingers feel like there's a million needles going through them here.
HOWARD DONNER: Yeah, just don't use your hands.
PETER HACKETT: The risk of frostbite is extremely high, and some people seem willing to accept it in order to get to the summit.
HOWARD DONNER: Can you straighten your fingers out a little bit?
NARRATOR: Every season, about 30 people will get frostbite. They pay a high price for the climb, losing fingers, toes, ears and noses.
HOWARD DONNER: I'm not causing you any pain here, am I?
NARRATOR: This climber was lucky, but others are not.
CLIMBER 2: I took my gloves off, and I noticed that this finger was black from about half way down the fingertip, and this one was black a quarter of the way down the fingertip.
NARRATOR: The first thing the body does in response to the sensation of cold is limit blood flow into the fingers and toes and funnel it into the core organs, the heart, lungs and brain. The cruel irony is that, in order to keep the core warm and alive, the body sacrifices its frozen extremities.
HOWARD DONNER: May have been frozen rather deeply.
PETER HACKETT: When the human body is exposed to a cold environment, it's wise enough to know it needs to protect its core organs. The body knows that it can survive without fingers and toes but it can't survive without a brain and without a heart, a warm heart.
NARRATOR: By now, Denali's fast changing weather clears, and Colby, Caitlin and Grunsfeld resume their ascent to High Camp.
CAITLIN PALMER: The ridge from 16,200 to 17,200 is probably the most scenic part of the West Buttress route. We had clouds below us—beautiful—weaving in between the rocks and sometimes right on top of the ridge itself.
NARRATOR: Despite the beauty, with each foot of ascent, the extreme cold and high altitude strain the climbers' bodies and minds.
CAITLIN PALMER: The objective dangers are falling to one side or the other, falling quite a distance, so that can be scary, the exposure.
JOHN GRUNSFELD: Well, the view is breathless, and so am I.
CAITLIN PALMER: So it took us eight hours, and we stopped for some nice long breaks.
NARRATOR: The higher the team climbs and the colder it gets, the more crucial it is to be on guard. For anything that incapacitates them physically or causes a lapse in judgment, could result in an accident or death.
JOHN GRUNSFELD: I'm just amazed to be up here at 17,200 camp. The air is very thin up here. We're at about half of what we have at sea level, right now. Little bit of a cough, nothing too serious I don't think, and a very, very mild headache when I stop. When I'm hiking, I'm breathing real fast, it seems to go away. So I'd say it's pretty much the telltale symptoms of acute mountain sickness.
COLBY COOMBS: Welcome to High Camp.
NARRATOR: This is the highest that astronaut John Grunsfeld has ever climbed. Even experienced climbers Colby and Caitlin are feeling the effects of the high altitude and extreme cold.
CAITLIN PALMER: I could feel my brain in my skull on the way up here—just at the very end—but I have actually been doing very well.
COLBY COOMBS: Yeah, rolled into camp pretty well. After an hour here, I started getting this mild headache.
NARRATOR: At 17,000 High Camp, as the team acclimates to the high altitude, low oxygen and extreme cold, the weather takes another turn for the worse.
COLBY COOMBS: We've got minus 50.
NARRATOR: Colby, Caitlin and Grunsfeld are going to have to wait for better conditions before making the final ascent to Denali's summit. They've carried enough provisions for 10 days. Hopefully, the storm will clear before the food runs out.
The next morning, a climber who's collapsed high on the mountain, is brought down to 14,000 Medical Camp.
HOWARD DONNER: Okay, feet first, feet first.
NOEL (RESCUED HIKER): You know, it's almost a nightmarish state. It's kind of scary.
HOWARD DONNER: And you had no energy?
NOEL: No energy.
HOWARD DONNER: This is an oxymeter.
NARRATOR: The fallen climber, Noel, has a blood oxygen level alarmingly low, only 60 percent. At 50 percent, people can lose consciousness.
CHRIS: The tank just died. Where's that tank?
HOWARD DONNER: It's outside.
NARRATOR: Without the help of bottled oxygen, Noel's blood oxygen saturation plummets further. Donner hurries to hook up a new tank.
HOWARD DONNER: Take a few deep breaths.
NARRATOR: The oxygen revives Noel, but Donner suspects his collapse may be a result of something more than hypoxia or A.M.S.
HOWARD DONNER: Noel, do you feel comfortable sitting up so I can listen to your lungs again? See if you've started to clear at all? Deep breath. Mouth open. Again.
NARRATOR: At high altitude, in order to increase the level of oxygen in the blood, the heart pumps more blood through the lungs. The blood vessels in the lungs, under increased pressure, swell. Eventually the air sacs, or alveoli, that transfer oxygen from the lungs, burst, and the lungs fill with fluid. It's a condition called H.A.P.E., high altitude pulmonary edema.
HOWARD DONNER: And that's what I'm hearing. I'm hearing the little crackly sounds that are probably due to the little snapping sounds that the little alveoli make as they open with a little bit of fluid in there.
NARRATOR: H.A.P.E. caused this climber to collapse. If left unchecked, his lungs will fill with fluid and he will literally drown. The only cure is to get him to a lower altitude. With less pressure on the blood vessels in his lungs, his air sacs will begin to repair themselves.
H.A.P.E. is a condition Donner and Hackett will watch for as the climbers make their bid for the summit.
At camp at 17,000 feet, after six days of waiting out the storm, and with food supplies dwindling, the weather clears. If Colby, Caitlin and Grunsfeld are going to make the last 3,000-foot ascent to the summit, it has to be now.
COLBY COOMBS: Sun's gone down, so the temperature's dropped. The wind's not too bad. We'll give it a shot. It's basically a question of whether we can move fast enough in order to stay warm.
NARRATOR: Colby leads out of High Camp. It will be their most difficult night. The physical and mental condition of each climber is crucial to the survival of the team. Every step they take involves a decision, and every decision is a matter of life or death.
But despite their excellent condition, experience and planning, once again the strange phenomenon Grunsfeld first experienced at 12,000 feet, is striking again.
As he heads up the mountain, his internal temperature rises dangerously high, while the outside temperature on the mountain plummets to 40 below zero. The thin air, barely half the oxygen at sea level, is making it extremely difficult for Grunsfeld to breathe.
COLBY COOMBS: NOVA 14 to NOVA 17. Do you copy?
NARRATOR: Colby radios down to Medical Camp, looking for advice.
COLBY COOMBS: Do you copy?
NARRATOR: But Hackett and Donner are out of range. Colby decides it's too cold and dangerous to stop here; they must push on to the summit. At midnight, the team reaches Denali Pass. They've climbed 1,000 feet in three hours, with 2,000 feet still to go.
Astronaut Grunsfeld is higher and colder than he has ever been on Earth. As he rests, his core temperature plummets. With the summit in reach, should he generate the lifesaving warmth by climbing to the top? Or will he need to save his last reserves of warmth to descend?
The team decides to return to High Camp.
COLBY COOMBS: We're back. It's 3:00 in the morning, left at 9:30, made it to the top of the pass, turned around and scrambled home.
CAITLIN PALMER: Just, uh, taking off my bigger gloves to put on my warmer gloves got my hands so cold, it was incredible. And then my core started getting cold, and I was shivering, too.
JOHN GRUNSFELD: It was pretty windy, pretty cold and pretty snowy on the way down.
NARRATOR: Grunsfeld's condition seems to be worsening. Can he recuperate at 17,000 feet High Camp? Will the team be able to make a second attempt on the summit? Or has Grunsfeld reached the limits of his ability to survive the extreme cold and altitude?
The team rests for two days at High Camp.
JOHN GRUNSFELD: Seventeen, two hundred camp for 14,200.
HOWARD DONNER: This is 14,000, go ahead.
JOHN GRUNSFELD: Hey Howard, how you doing? John Grunsfeld here.
NARRATOR: Grunsfeld establishes radio contact with Medical Camp.
HOWARD DONNER: How're you sleeping, John? And how's your energy and appetite? Over.
NARRATOR: This is the moment of truth.
JOHN GRUNSFELD: Night before last I didn't sleep very well, and so yesterday morning I woke up with a kind of a massive headache.
NARRATOR: The climbers face a tough decision. With the summit in reach, should they make a second attempt?
With a pounding headache and low blood oxygen levels, Grunsfeld has all the classic symptoms of A.M.S., acute mountain sickness. And now his cough suggests that the air sacs in his lungs are filling with fluid, the first sign of H.A.P.E., high altitude pulmonary edema.
JOHN GRUNSFELD: Waiting around, day after day, can get pretty tiring, and you kind of wonder whether you are acclimatizing more or not. And I think for a few days you acclimatize well; after that you just sort of reach a plateau.
NARRATOR: The final choice about whether to summit comes down to data produced on this expedition, and never before available to climbers, the core body temperature readings from the thermo pill.
PETER HACKETT: Core temperatures went up as high as 103 degrees in John, and then, when he stops, we get this unbelievable documentation that his core temperature plummets.
NARRATOR: And while Grunsfeld's temperature fluctuated between dangerous highs and lows, Caitlin's core temperature stayed within two degrees of normal.
Hackett and Donner suspect the huge fluctuation in Grunsfeld's core temperature may make him more susceptible to Denali's lethal combination of extreme cold and high altitude.
PETER HACKETT: As far as I know, it's the first data like this, with careful measurements, reliable measurements, in active climbers.
NARRATOR: Over three weeks, the team has climbed 10,000 feet. They are now just 3,000 feet from standing atop the highest mountain in North America. The summit is a powerful lure.
COLBY COOMBS: All right, John.
JOHN GRUNSFELD: Thanks a lot, Colby.
NARRATOR: Colby remains at 17,000, and based on the data from the thermo pill, Caitlin guides Grunsfeld down the mountain.
JOHN GRUNSFELD: Seven days is a long time to spend up at a high camp. The winds had abated, and we had decided that this was a window for us to come down, or at least an opportunity that may not have presented itself for days. Of course, tugging at me back up the hill was the thought that, "Well, I'm giving up, for this expedition, the chance to go to the summit."
PETER HACKETT: I'm totally amazed that there aren't more deaths on Denali, totally amazed. There are so many people that squeak by just barely. They have no idea how close they were to dying.
NARRATOR: Without an accurate measure of internal temperature and an understanding of what it means, other climbers may elect to push on. But that decision can cost many climbers their lives.
With Caitlin and Grunsfeld descending, now Colby must decide if he is strong enough to reach the summit.
COLBY COOMBS: NOVA 14, this is NOVA 17, do you copy?
HOWARD DONNER: Howard Donner at 14. Go ahead.
COLBY COOMBS: Hey Howard, this is Colby, up at 17. How's it hanging down there?
HOWARD DONNER: Colby, we've got some problems. There's a plane with the new patrol coming into 7,000—a ranger and two volunteers and, of course, the pilot that are missing from last night. And there was some squirrelly weather. We're not very optimistic.
COLBY COOMBS: Can you tell me, ah, the ranger please?
HOWARD DONNER: Uh, Colby, it was Cale.
COLBY COOMBS: Copy that.
NARRATOR: The plane flying into base camp at 7,000 feet, crashed. On board were the pilot, two rescue mountaineers and a park ranger. The ranger, Cale Shaffer, and Colby were close friends. Often it is the people who volunteer to help save lives on Denali who are most at risk.
From High Camp, Colby chooses to push on for the summit.
COLBY COOMBS: My best times and my worst times of my life have been in the mountains. I've been in an accident where my best friend has died and I'm tied to him. You can have your own trauma of losing your friend. But it's a whole different level of traumatic experience when you're staring at a parent who's just lost their son or daughter, and they're looking at you, and they're saying, "Why? Why did this happen? This is just a sport. Where? What went wrong?"
NARRATOR: Those who seek the summit and reach the top are few. Their motivations vary: national honor, personal achievement or just to see the view from the top of the world. Whatever their reasons, as long as climbers pit themselves against the Earth's tallest peaks, scientists will continue their search to understand the limits of human survival. Perhaps one day they will all find what they are looking for on what may be the coldest mountain on Earth, the high one, Denali.
On NOVA's Deadly Ascent Web site, make a virtual climb of the demanding route from base camp to the summit of Denali. Find it on PBS.org.
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