Spacelab Life Sciences Mission
The Spacelab Life Sciences is a series of Space Shuttle missions designed to carry out NASA's research program for supporting humans in space. Successful human exploration of space depends on the health and well-being of the people who travel and work there, and the SLS-1 mission will investigate some of the problems that occur in space through experiments designed by scientists and carried out by the astronauts. An added benefit is that the research pursued in the space environment will help us to understand many ailments suffered by people on Earth, such as hypertension (high blood pressure), and other heart and cardiovascular problems. In addition, bone and muscle research in space can give us added important insights into muscle degeneration and osteoporosis (loss of calcium in the bones), all of which are health problems facing society today. There are 20 scientific investigations on SLS-1 examining the following six body systems: + the renal/endocrine system (kidneys and hormone-secreting organs); + the blood system (blood plasma and red blood cells); + the immune system (white blood cells); + the musculoskeletal system (muscles and bones); and, + the neurovestibular system (brain and nerves, eyes, and inner ear).The Cardiovascular/Cardiopulmonary System
Due to a headward shift of body fluids, scientists expect the cardiovascular-cardiopulmonary system to show measurable adaptations to microgravity very quickly. In addition, since this system interacts with every organ in the body, small changes in the cardiovascular/cardiopulmonary system propagate throughout the body and are important to measure carefully. Six of the SLS-1 experiments focus on the heart, lungs, and blood vessels. Extensive measurements will be made of heart size, blood pressure, heart rate, blood volume, blood flow patterns, characteristics of blood vessels, and lung function. All of these measurements together make it possible to chart this system's adjustments as the body redistributes fluid during space flight.The Renal/Endocrine System
The kidneys and the endocrine (hormone control) system are part of the body's fluid regulatory system. The kidneys control water balance and the removal of waste products, and help regulate blood volume and blood pressure. Hormones are secreted throughout the body to control various functions, such as thirst, urinary output, and blood pressure. These chemical messengers may initiate a response in one organ or may coordinate activities between systems. One of the main functions of the kidneys and hormones is to regulate blood volume. The responses of this system to microgravity will be closely linked to those of the cardiovascular system.The Blood System
The hematology (study of blood) investigations on the SLS-1 Mission will study two parts of the blood system, the liquid plasma and the red blood cells. Previous space-flight studies have shown reductions in the levels of both blood plasma volume and red cell volume. This investigation which utilizes human subjects, and two other investigations using laboratory rats, will examine the mechanisms by which red blood cells seem to be lost from the body.The Immune System
An SLS-1 investigation has been designed to examine certain white blood cells (lymphocytes) and their production in weightlessness. Lymphocytes help the body resist infection by recognizing and neutralizing harmful foreign substances, such as bacteria. To date, analysis of lymphocytes from Shuttle crew members has shown a marked decrease in the number of lymphocytes circulating in the body, as well as a decrease in their ability to respond to challenge. However, the astronauts have shown no apparent increased susceptibility to disease and their white blood counts returned to normal within a few weeks of landing.The Musculoskeletal System
Previous space experiments using laboratory rats showed that certain leg muscles lost approximately 40% of their mass after seven days of microgravity exposure. Related findings included an almost complete absence of leg muscle tone and a marked decrease in muscle fiber diameter. Human studies carried out in space have also shown a loss of muscle mass after months of space flight despite a vigorous program of exercise. The SLS-1 Mission has one human and three laboratory rat muscle investigations, making and comparing measurements on protein synthesis and breakdown rates, concentrations of protein and enzymes in muscle cells, shrinkage or death of muscle cells, and breakdown of muscle fibers. On Earth, the skeletal system of the body serves as both the framework for the body itself and as the support system which enables the body to maintain its normal posture. Weightlessness causes a slow loss of bone minerals. Crew members from previous space flights have shown a continuous loss of calcium, an important component of bone, and laboratory rats have shown decreased growth of certain areas of their skeleton following space flight. Two experiments on SLS-1, one human and one in rats, will examine the changes in the amount of calcium absorbed into the body and the amount of calcium excreted by the body, and will study the hormones in the blood which are related to bone growth and loss.The Neurovestibular System
The neurovestibular system consists of organs which sense the acceleration environment, nerves which transmit this information to the spinal cord and brain, and an organizational center in the brain which integrates this information so that we can determine how to respond to the environment. The eyes, the inner ear and the special receptors in muscles and joints all participate in maintaining posture and balance, and assist us in our motion from place to place. During previous space missions, these systems have been studied, and crew members have reported that head movements in space have played a part in inducing space motion sickness, and illness similar to motion sickness on Earth. Three investigations on SLS-1 concern the neurovestibular system and its relationship to space motion sickness. In the human experiment, the main objective is to determine how the body, which receives multiple signals from several sensory sources, interprets this information in microgravity and on Earth immediately following space flight. Another objective of this investigation is to record and characterize the symptoms of space sickness experienced by crew members. Two experiments, one with laboratory rats and another with jellyfish, will study gravity sensing structures directly to see if microgravity causes physical changes in these structures. + Humans in Space: Environmental Challenges (Back) + Hangman
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