 T minus 30 seconds, initiate systems check. Musculoskeletal system. Musculoskeletal system is go. Neurovestibular system. Neurovestibular system, go. Cardiopulmonary system. Cardiopulmonary system, go. Cardiobascular system. Cardiobascular system, go. All systems are go. We are T minus 10, 9, 8, 7, 6, 5. 2, 1, we have liftoff. We have liftoff. 9, 8, we have a goal for main engine start. We have main engine start. 4, 3, 2, 1, 0, and liftoff. Liftoff of the space shuttle, and it has cleared the tower. It's very small. It is small, but it's the case. Yeah, you're touching it. The Space Shuttle Columbia and Spacelab Life Sciences won. After 10 years of flying space shuttle missions, we're becoming accustomed to the strange things that can happen in space. But it hasn't always been that way. When we first went into space, no one knew how the human body would react to space flight. We wondered if we could survive in weightlessness. And we wondered if we could work in space. OK, I'm on. OK, he's out. He's low-frequency. 30 years later, we know that the answer to both of these questions is yes. But in spite of our successes in space, many questions about the effects of space flight on the human body remain unanswered. During the flight of Spacelab Life Sciences won, my colleagues and I will try to answer some of these questions. The human body is much like the shuttle. It is a very complex, sophisticated piece of living machinery that relies on several subsystems to perform its mission, where the shuttle has a propulsion system, a life support system, a guidance system, and so on. Our bodies have systems like the cardiovascular system, the cardiopulmonary system, the renal endocrine system, the blood and immune systems, the musculoskeletal system, and the neurovestibular system. The shuttle systems communicate with each other to keep the spacecraft flying smoothly. In a similar way, our body systems also talk to each other to maintain what is called homeostasis or a stable internal environment. All of our body systems are affected to some degree by spaceflight. The most dramatic change occurs immediately after we become weightless. On Earth, the pull of gravity normally pulls our body fluids in our feet, legs, and abdomen. But when we enter space and become weightless, the fluid in our bodies is no longer pulled down toward our feet. Instead, it shifts up to our chest and head. Since 80% of our body is fluid, that changes the way we look. Our faces get puffy and our legs get skinny. We call this the bird legs of space. After we're up here for a while, we adapt somewhat to the fluid shift. But our bodies remain in this altered state until we're back on Earth. The weightlessness affects our bodies in another way, too. It's called space motion sickness. It's much like being seasick on Earth. But luckily, our bodies adapt to this new environment. And so it isn't really a problem after the first couple of days. The fluid shift in space motion sickness are easily recognizable changes that take place in weightlessness. But less obvious changes also occur, right down to individual cells. During the flight of STS-40, Space Lab Life Sciences 1, my fellow crew members and I will introduce you to the six major body systems. We'll learn how they function on Earth and how space flight may affect them. Our cardiovascular system is a network of over 96,000 kilometers of blood vessels, enough to go more than twice around the Earth. These blood vessels include arteries, which carry freshly oxygenated blood to all the tissues in our bodies, and other vessels called veins, which bring back waste-laden blood so that the process can be repeated. The driving force of the cardiovascular system is the heart. It's a pump that forces blood through the arteries and the veins. Our heart pumps or beats about 60 times a minute every minute of our lives. If you live to be 70 years old, your heart will pump more than 2 billion times. Our cardiovascular system works well in gravity. Whether we're lying or standing, we always have an adequate supply of blood for vital organs, like the brain. But when we go into space and take our hearts out of their normal environment, some strange things happen. The upward shift of fluid in our bodies tricks the heart and its sensors into believing that there's an increased blood supply. So our heart tries to compensate first the muscle structure of our heart stretches so that it can hold more blood. When this happens, other body systems tell our kidneys to eliminate what appears to be excess fluid. As the fluid level is reduced, we believe our bone marrow shuts down its production of red blood cells in order to keep our blood from getting too thick. Pretty soon, the amount of blood and the red cells in our body is less than we have on Earth. With less blood to pump, our heart shrinks. Back to about the same size that is on Earth. But when we return to Earth from space, gravity again pulls much of our blood back to our legs. Now there's not enough blood to go around and some of us will get lightheaded and dizzy for a short time until our bodies get more fluids and manufacture more blood. In spite of this, there's no indication that spaceflight causes any permanent problems for our cardiovascular system. But during this flight, we're going to investigate this matter more closely. Before we departed Earth, I had a long plastic tube inserted into a vein in my arm. This tube is called a catheter. The tube was advanced in a vein to a point just above my heart. During the first few hours of flight, when the fluid shifts occur, we're able to measure the central venous pressure near my heart. Central venous pressure is directly related to the volume of blood our heart pumps. Once we get back to Earth, we'll do the same experiment and see if the central venous pressure measurements differ. If our suspicions are correct, we'll demonstrate that the fluid shift caused by weightlessness increases activity and changes the control mechanisms of the heart in circulation. Information like this will help us to better understand the changes we go when we first center weightlessness and it will give us insight into the possible effects of long-term weightlessness as well as diseases of Earth-bound patients. The cardiovascular system works closely with another body system called the cardiopulmonary system. Cardio refers to the heart and pulmonary refers to the lungs. This lung-heart connection is right in the middle of the cardiovascular system, but not literally. Here's what I mean. The heart pumps blood through our arteries and veins. The blood in turn has an equally important job. When the blood is on its way to our tissue and organs, it is said to be oxygenated, meaning that it is carrying oxygen to all of the cells in our bodies. When blood is returning from the cells, it is oxygen depleted, meaning that the oxygen has been used up and in its place is carbon dioxide. Looking at a diagram of the cardiovascular system, we see that it's a closed system. If this is true, then how does the blood get a fresh supply of oxygen to carry back to the cells? That's where the lungs come in. Oxygen-depleted blood is pumped from the heart to the lungs. Think of the lungs as two large airbags filled with thousands of tiny blood vessels called capillaries. My friend here is gonna help me show what happens when we take a breath of air. When we breathe, air rich with oxygen enters the lungs. Now we've got two lungs full of fresh air and oxygen, and we have a network of small blood vessels filled with oxygen-depleted blood. Now something quite fascinating happens. The oxygen in the lungs and the carbon dioxide in the blood are going to trade places through the thin membranes that line the lungs. This phenomenon is called gas exchange. Now the air in the lungs is oxygen-depleted and the blood is oxygenated. Okay, now you can breathe. Thank you. The blood then returns to the heart where it's pumped out to the body to nourish the cells and give them oxygen. It then returns back to the heart and then again to the lungs where the processes get repeated. On earth, where gravity tends to pull blood toward our feet, the majority of the blood in the lungs stays near the bottom and the air stays mostly in the top. But in space, where the fluid in our body shifts upwards, it is felt that there will be a more even distribution of blood and air in the lungs. That means that the lungs should function even more efficiently in space than they do on earth. Space Lab's gas analyzer is going to help us determine if this is true. By breathing into the rebreather device, we'll inhale a mixture of traceable gases. When we exhale the mixture, the gas analyzer will identify each gas and determine the quantity that was absorbed by the bloodstream. Investigators back on earth will then be able to determine if gas exchange in the lungs is actually more efficient in space. If that is the case, it may help us to better understand certain respiratory problems that people have back on earth. If you're a healthy young person weighing about 120 pounds, over 60% or 72 pounds of your body is made out of water. That means that water is the most abundant and the most important fluid in your body. But how do we keep our body water at a constant level? Every time we perspire or go to the bathroom, we rid our bodies of water. And every time we take a drink of water, we add water back. So how does the body keep the water in balance? This is done for us automatically by our renal endocrine system. Renal refers to the kidneys and the endocrine system is a collection of hormone-secreting glands that include the hypothalamus, the pituitary, the thyroid gland, the pancreas, and the adrenal glands. The primary body compounds regulated by this system are water and electrolytes. When we drink water or other fluids, they go into our gastrointestinal tract. From there, water and electrolytes are absorbed into the bloodstream by a process called osmosis. The cells in our bodies then absorb whatever water they need from the bloodstream. The cells also dump water along the cellular waste into the bloodstream. As the blood passes through our endocrine system, it is monitored for different metabolic products. Ugh. Ugh. Ugh. Phew. Two of the endocrine glands, the hypothalamus, and the pituitary monitor fluid levels in the blood. If the fluid level is not right, they will release a hormone. And that hormone tells the brain there's a problem. If the fluid level is too low, the brain tells us that we're thirsty. But if the fluid level is high, the brain tells the kidneys to eliminate fluid. Through an elaborate filtering process, our kidneys remove the excess fluids and waste from our blood and store it in our bladder in the form of urine. When our kidneys are told by our body to get rid of the water, we make more urine in the body. Our bladder is filled and we get the urge to urinate. But what does all this mean for the space traveler? For one, it means that when we enter weightlessness, the body fluids shift upward. And our renal endocrine system will tell our bodies to eliminate fluid. What we don't know is how weightlessness affects the production of hormones that keep our fluid levels balanced. Here on SLS One, we're investigating all the changes that occurred during space flight, changes in the hormone production, changes in how the kidney functions, and the circulation. And with this new knowledge, we hope to shed new light on things like how and why we be conditioned during space flight, and on earth problems, like orthostatic hypertension and heart failure. All of us know that blood is essential for life. But do we really know why? Blood has two very important jobs. First, it transports oxygen and carbon dioxide to and from the millions of cells in our bodies. Blood is also a defense mechanism that allows our bodies to fight infection and disease. Blood has three components. Red blood cells, which do the transporting of oxygen and carbon dioxide, white blood cells, which fight infections, a watery fluid called plasma, which makes our blood liquid and allows it to flow through the blood vessels. Let's take a look at each of these components a little closer. Red blood cells could be compared to millions of taxi cabs zooming around in our bodies. As each red blood cell taxi passes through our lungs, it's flagged down by an oxygen molecule. The oxygen is wanting to go to one of the millions of cells that makes up our bodies. So the red blood cell takes off through the cardiovascular system toward that destination. Once there, the oxygen gets out and goes to the cell. Now, like any good taxi driver, the red blood cell doesn't want to make a return trip without a paying customer. So while at the cell, he picks up a carbon dioxide passenger for the return trip to the lungs. Without red blood cells, our cells can't get the oxygen they need to sustain life. White blood cells also perform an important function. They are a major part of our immune system. From time to time, foreign substances enter our bodies. These substances might be bacteria, viruses, or even something like a splinter. We might compare the white blood cells to a good watchdog in our yard. When someone or something harmful comes into our yard, our watchdog will attack it. White blood cells work the same way, except there are millions of them. When a foreign substance enters our bodies, the white blood cells attack and repel the intruder. There are several types of white blood cells, but the ones that we're interested in on this flight are called lymphocytes. The red and white blood cells would have a difficult time making it through our blood vessels if it weren't for our liquid called plasma. In the red fluid we call blood, cells make up about 40 to 45 percent. The rest is plasma. Since plasma is a fluid, it is really affected by the upward fluid shift that takes place in our bodies when we first encounter weightlessness, and that affects our body's overall blood supply. Here's how. When the fluid in our bodies drifts upward, sensors in the circulatory system and the endocrine system send a message to the brain saying that there's too much fluid. The brain then tells the kidneys to reduce the fluid volume. This is probably accomplished mainly through urination. Once the fluid level has been reduced, blood cells make up more than 45 percent of the blood supply. In other words, our blood becomes thicker. For one sake for this, we think the bone marrow decreases its production of red blood cells until the ratio returns to about 45 percent. So once again, our bodies adapt to the changes of spaceflight. But when we return to Earth, we face another problem. We find that we've lost both blood volume and red blood cells. The loss of blood volume is a problem immediately upon returning to Earth because Earth gravity is again pooling blood in our legs. The decreased volume makes it more difficult for blood to be pumped to our brain. This can lead to lightheadedness and a woozy feeling right after landing. We begin working to correct this problem even before we land by drinking lots of water. By drinking water, we begin to replace the plasma in our blood. But once the plasma level is increased, we face another problem. Now we have fewer red blood cells than we should have. This condition is called space anemia even though it doesn't actually happen until we're back on Earth. Space anemia will continue until the body manufactures enough red blood cells to bring the plasma cell ratio back to about 45 percent. During the SLS-1 mission, we're studying several ways in which spaceflight affects the blood and immune system. For example, in the past we have found that astronauts have fewer lymphocytes after flying in space. And the lymphocytes they did have were not as effective in fighting infection as they had been prior to spaceflight. At various times throughout this mission, we're going to draw blood from the prune. These specimens will be studied later on Earth to determine if the lymphocyte's ability to enter infection decreases the longer they remain weightless. This is an important question to be answered. Without a functioning immune system, our bodies would become easy prey for disease. Most structures are designed with a specific purpose in mind. The orbiter was designed to function in the unique conditions of space. Our bodies were designed to function on Earth where there's gravity. In fact, our body's musculoskeletal system needs gravity to function properly. Of all the body systems we're studying during SLS-1, the musculoskeletal system may be the only one that has serious problems adapting to the changes it encounters during spaceflight. By pulling against our bodies, gravity makes our bones and muscles work and become stronger. Each time we take a step and push our weight forward, we perform a weightlifting exercise for the muscles in our legs. Activities like climbing stairs make our muscles work even harder. But in space, nothing has weight, our muscles don't have to work the same as they do on Earth. When muscles don't work in their usual way, they become weaker. Most of us have known someone who's broken an arm or a leg and had to wear a cast while the bone healed. While in the cast, the muscles of that arm or leg didn't have to work. And once the cast was removed, the muscle was weak and had lost its bulk. The same is true for people who've been confined to a bed for a long time and could not use their muscles. In space, we work our muscles on treadmills and exercise bikes, but the results still aren't the same as they are on Earth. Imagine that every day we lift the barbell that weighs 100 pounds. Then, one day we go on a trip that lasts a month and we only have a 40-pound barbell to take with it. Even though we lift the 40-pound barbell every day, the 100-pound barbell is going to be hard to lift when we return from our trip. The same is true about spaceflight. Even though we exercise in space, we're going to be weaker when we return. Depending on how long we've been in space, it may take us weeks or even months to regain the strength in our muscles that we've lost. It could be even worse for astronauts who will someday live on the space station or at lunar bases. Not to mention a trip to Mars that could last a year or more. The muscles aren't the only parts of our bodies that suffer during spaceflight. Weightlessness also causes our bones to lose the minerals, calcium, and phosphorus. Many of us don't think of our bones as being alive, but they are really very active. In our bone are two types of cells, osteoclasts, which get rid of old bone matter, and osteoblasts, which build new bone. Because of the activity of these two types of cells, our bones are in a constant state of tearing down and rebuilding. The balance of these cells seems to be tipped slightly in favor of the osteoblast cells. That's why our bones grow stronger. But what happens in space is still somewhat of a mystery. Since there is no weight to bear in space, then there is no stress on our bones as they go through the rebuilding process. This seems to affect the structural integrity of our bones. Bone density recovers, but without stress, we cannot grow as strong. The only way to prove this theory is to test some of our bones for strength. And the only way to do that is to remove the bone. And so far, we've had no volunteers. So NASA is working on ways to study bone strength without removing the bone. Finding a way to test bone strength is going to help us to treat elderly patients who have a common bone problem known as osteoporosis. Here on SLS-1, we're going to measure the level of calcium-producing hormones and compare them directly to the uptake and release of calcium in the body. It will be the first time that this has been done in the weightlessness of space. It's a spectacular view out the window. But most of the time, looking outside doesn't tell us if we're flying in the way we should. Since there aren't a lot of visual references in space, the shuttle has a guidance system that helps keep us in a proper position. There's no guidance system in our bodies, too. It's called the neurovestibular system, and it's what keeps our bodies in the proper orientation on Earth. The neurovestibular system is very sensitive to gravity. In fact, it's gravity that makes it work. Deep inside our inner ear, in the vestibular organ, are thousands of tiny hairs. Resting on top of these hairs are microscopic clumps of crystals called otoliths. On Earth, gravity pulls the otoliths in different directions, according to the type of activity we're doing. This, in turn, bends the tiny hairs, sending messages that tell the brain if we're hanging upside down. Accelerating. Or any other sensation that has to do with body movement. The neurovestibular system also uses sensors in our muscles that determine sensations of motion or changes in position. But most of all, it relies on our eyes. We might even say that the neurovestibular system's main purpose is to create a stable platform for our eyes. When our eyes can't lock onto what we're looking at, we can get a queasy feeling we call motion sickness. It's the same feeling some people get when they ride a wild ride at an amusement park. Everything rushes by in a blur. And before long, they think they might get a second look at the hot dog they just ate. Some of us who fly in space get a similar feeling. We call it space motion sickness. That doesn't mean riding the shuttle is like climbing aboard a tilted wheel at a carnival. But it does mean that space flight can confuse our neurovestibular system and disorient the visual references we rely on for stability. There's a reason for this. When we get into space, gravity no longer pulls down on us the way we're used to on Earth. Things start to float away. And for all practical purposes, objects become weightless. In this environment, the vestibular system functions differently than it does on Earth. And we no longer have a way to tell our brain what the right body position is. Without the vestibular system functioning the way we're used to, some of us get confusing signals in our brain. Our eyes tell us that our feet are off the ground. But our vestibular organ doesn't give us the sensation of falling that we expect. Usually after a few days in flight, our bodies adjust to the weightlessness and the space motion sickness goes away. Not everyone experiences space motion sickness. And that's one of the medical mysteries we'd like to know more about. The reason is quite obvious. Imagine getting off a ride at a carnival and someone hands you an algebra book and tells you to work a few problems. That's what it's like for an astronaut who's suffering from space motion sickness. It's rather difficult to concentrate on an experiment if all you can think about is how sick you feel. We want to have as much productive time as possible when we're in space. So to help us learn more about the effects of space motion sickness and how to treat it, we're going to do some experiments here on SLS-1. One of my favorite experiments involves this rotating dome. What the dome does is to help us see how visual cues affect the way our body responds. To do the experiment, Millie will put her head in the dome and look at the dots as they rotate. Her eyes naturally want to lock onto the dots. This causes her body to want to keep up with her eyes. And pretty soon, her whole body will feel like it is turning. But it really isn't. A camera mounted in the dome is recording her eye reaction. Back on Earth, scientists will study this and other data we've collected to see if they can answer some of the questions about how our neurovestibular system works and why we get space motion sickness. I'll leave you with a small bit of advice. The next time you're on a roller coaster ride and you feel yourself getting sick, just close your eyes. Our body systems are so different from each other yet they all depend so much on each other. They perform their jobs each day in a way that most of us never realize. Our goal at NASA is to enable the human exploration of space. But to do that, we have to understand how space affects our bodies. Space lab missions like this one are a step toward that goal, but only a small step. Orbiting laboratories will allow us even longer periods to investigate the mysteries of the human body. Hopefully, the benefits of all space-based research may someday help solve the puzzles of such earthbound problems as heart disease, emphysema, osteoporosis, and other disorders. The possibilities are as limitless as the stars themselves. Space Lab Life Sciences 1 has been a valuable learning experience for all of us. We're really glad you could join us on this voyage of medical discovery.