Space Biology, Earth, and Health by Dr. Timothy Smith

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Due to our exceptional adaptability, humans occupy almost every type of environment on earth from baking hot deserts to frozen tundra and everywhere in between. With the help of technology to shield us from the elements, people have traveled to extreme heights, extreme depths, and all the way to the moon. Our biology shifts depending on our environment, and when it comes to  microgravity in orbit around the earth, or even zero gravity in deep space, our biology changes significantly. Some of our adaptations to microgravity have long term negative effects on our bodies that need attention if we are to successfully travel long distances or work in space.

Human biology shifts in changing environments. For example, when people accustomed to living at sea level with denser atmosphere move to high elevations such as Denver, Colorado at a mile above sea level they can experience a lack of sufficient oxygen. This lack of oxygen, or anoxia, can lead to purple lips and gums, dizziness, and even fainting. However, given enough time people accustomed to low land, one’s body will begin to produce more red blood cells to better capture the scarce oxygen in the air. Boosting red blood cells also helps athletes to perform at a higher level, which is why many athletes will train at high altitudes to bolster their red blood cell count before major competitions. Another example of biological adaptation comes from the changing fat composition in our bodies that comes as temperatures fall in the transition from Autumn to winter in northern climates. As the temperature goes down, the body will replace some the long chain unsaturated fats that comprise our cell walls with saturated fats that melt at a lower temperature. Saturated fats have little kinks in them that make them stack, making it harder for the fats to go from a solid to a liquid. To visualize this, think of the difference at room temperature between olive oil and butter. Olive oil, which has more unsaturated fat than butter, stays liquid at room temperature (where butter will stay solid). The change in fat composition keeps cell walls fluid for optimal function.

Some biological adaptations that humans have evolved in the constant force of earth’s gravity cause problems when in space. For example, our bones need constant pressure and strain against gravity to remain strong. Bones have stress detectors that send a signal to the cells (called osteoblasts) that build and maintain bone structure. Whenever those cells receive that stress signal, it’s the sign for them to keep building the bones. In the absence of such signals, another type of bone cell, called an osteoclast, will break down bone tissue, making the bones lighter and weaker. Excessive bone loss leads to a condition called osteopenia and eventually osteoporosis that makes bones more susceptible to fracture under normal conditions. NASA noticed that astronauts suffered bone loss over extended time in micro and zero gravity. If you notice footage from the International Space Station, you see the astronauts exercising and stressing their bones to stave off bone loss. Additionally, a lack of gravity also affects the heart, causing a decrease in heart rate, blood, plasma, and heart condition. Similarly, loss of vision, muscle mass and strength occurs in microgravity. More careful research also demonstrated that the immune function of astronauts deteriorates with decreasing numbers of killer T-cells that fight foreign bodies and an increase in allergies and autoimmune problems.

The human body has through biology and technology adapted and survived the most inhospitable places on earth, in the ocean, and even in space. But our travels into the extremes of space indicate that our biology, built in the unyielding embrace of earth’s gravity, begins to shut down key processes when we leave the atmosphere. The question for the next generations of humans who will explore, work, and even vacation in space involves how can we adapt technologically to the deleterious effects on our bodies in zero gravity. Considering our ambitions to travel to Mars which would involve 7 to 9 months of travel time in zero gravity, medicine needs to find physical and therapeutic assistance for the astronauts to not only arrive healthy on Mars, but also stay healthy enough for the ride back to Earth.   

Dr. Smith’s career in scientific and information research spans the areas of bioinformatics, artificial intelligence, toxicology, and chemistry. He has published a number of peer-reviewed scientific papers. He has worked over the past seventeen years developing advanced analytics, machine learning, and knowledge management tools to enable research and support high-level decision making. Tim completed his Ph.D. in Toxicology at Cornell University and a Bachelor of Science in chemistry from the University of Washington.

You can buy his book on Amazon in paperback and in kindle format here.