By A. S. Deller | 29 January 2021
“It is a very sobering feeling to be up in space and realize that one’s safety factor was determined by the lowest bidder on a government contract.”
– Alan Shepard
Little research was actually done to determine the full extent of what spending long periods of time in space would do to the human body prior to our first manned launches out into the void. Even less was understood about the potential psychological outcomes that might resolve when people travelled farther away from home than anyone ever had before, just to end up locked inside a metal container for 99+% of their time (often measured in months).
Life is perhaps the rarest occurrence in the universe. It seems to require extremely unique conditions in order to arise: a world none too far or close to its star, with sufficient energy sources (sunlight, geothermal heat) and elemental content (oxygen, nitrogen, carbon, phosphorus, etc.), liquid water, a protective magnetosphere and atmosphere, and numerous other variables.
In the proper conditions – a very narrow band of conditions with a chance of existence just shy of zero in our universe – life thrives. Removed even slightly from those conditions, life cannot continue.
Patients on earth with illness can be described as people who live in a normal earth environment but who have abnormal physiology. In contrast, astronauts are people with normal physiology who live in an abnormal environment.
– David Williams, et al.
Physiological and Psychological Effects Over Time
During an astronaut’s time engaged in space travel, various effects occur throughout the duration. Some can be immediately measured, while others become apparent over the course of days and weeks.
During launch out of the gravitational grip of a celestial body (in our case, Earth): Fluids are redistributed to the torso and head, with legs losing up to 10%. Many subjects experience motion sickness.
Over the course of days to over a month of zero-G space travel, whether in orbit or toward a destination such as Mars, an astronaut will experience a wide array of symptoms: Up to a 17% reduction in plasma volume and 10% decrease in overall blood volume; up to a 30% reduction in muscle tissue and 50% loss of strength; a continual loss of bone density (1-2% per month) driven by lowered parathyroid and vitamin D production and 60+% calcium loss; and lowered immune response.
Psychological effects build up over time in space as well. Sleeplessness and fatigue can be immediate, while the stressors of isolation, homesickness and worry over friends and family back on Earth increase with every day spent away.
Following a single 1-6 month stay in space, an astronaut can take a year or longer to fully recover bone and muscle mass, which means the physical and psychological toll extends well beyond the travel window.
Aerobic, strength and resistance exercises, as well as dietary supplements, are utilized to help counter the deleterious physical effects during space travel, while drugs like modafinil are taken to maintain performance with reduced sleep.
Despite all of our modern knowledge and experience, though, some results may be permanent:
Gray matter is the actual clump of neurons that make up the “thinking” parts of the brain. In Earthbound experiments seeking to recreate the effects of weightless, zero gravity existence (using a self-explanatory technique called “head-down tilt bed rest”), researchers discovered that extended periods of such resulted in a decrease in volume of gray matter in the bilateral frontal lobes. Those areas of the brain are responsible for active processes like cognition and voluntary movement. However, an increase in gray matter volume was noted in a part of the cerebellum responsible for limb coordination. At first glance, these changes appear to be contradictory in nature. The researchers concluded that the boost in limb coordination may be a result of the brain compensating for the slight decrease in the bilateral frontal lobes.
“And in that moment, I was hit with the realization that this delicate layer of atmosphere is all that protects every living thing on Earth from perishing in the harshness of space.”
– Ron Garan
After the initial period of some dozens of astronauts moving to Mars to establish a settlement, there will come a time when larger numbers of people will move there to make it a home. As hundreds, and ultimately thousands, of settlers undertake the long term work of making Mars suitable for potentially millions of humans and a vast array of other Earth life, children will begin to be conceived and born on an alien world for the first time.
In Shannon Stirone’s excellent Medium article The Challenges of Having Children in Space, the author uses the case of the “bubble boy” David Vetter, a child born with Severe Combined Immune Deficiency in 1971, to illustrate how children who may be born in space stations or settlements on other worlds would be negatively affected by the isolation and reliance on technology for even the barest necessities of life. By the time this becomes commonplace, however, I believe there will be a large enough population present to counter most of those negative effects.
The real question becomes: How will a microgravitational or alien world environment impact the development of a human fetus and, ultimately, a growing child?
So far, there has been no direct experimentation with human child development in space. However, some research has been done sending pregnant rats into space, by both the Soviet Union and the United States. Most notably, researchers in 2001 sent 20 pregnant rats into orbit on the Space Shuttle. Their fetuses were roughly halfway through development. The findings showed that the baby rats born in space experienced some slight underdevelopment of their vestibular systems – the structures that affect balance inside the ears. These rat babies caught up to their Earthborn control “cousins” after a few weeks of balance training once they returned to the surface.
Microgravity in orbit or on a planet (or moon) of much lesser mass than Earth would of course cause other problems. Lower bone and muscle mass would be likely, and chances of ectopic pregnancy, in which the fertilized egg implants somewhere other than in the uterus, would probably be very high. The increase in radiation would also add up to an increase in chromosomal and DNA damage as well as more possibilities of childhood cancers. Settling on a world with gravity similar to Earth’s and a protective atmosphere and magnetosphere would prevent those problems. Living on a space station would require immense amounts of radiation shielding using thick walls of asteroid rock and/or water tanks. The station would also need to spin sufficiently to generate centrifugal force as a kind of “artificial gravity”.
Though we don’t know much now, as we begin to build more structures in space and visit the Moon and Mars, there will be great advancement in our medical knowledge of life in space over the next 10-50 years.
Evolution Among the Stars
As long as Homo sapiens reaches a point where the settlement of other worlds becomes an option, the incredible power of evolution will eventually come to bear on our future in space. Humans that are born and grow up on Mars, for instance, will be subjected to 2/3rds less gravity than they would be on Earth. Less encumbered by gravity, they will likely have less dense bones and grow taller. Conversely, humans who settle on much more massive worlds, such as Kepler 10c with 17 times Earth’s gravity, will develop much stronger skeletons and shorter, but more robust, physical builds.
Those changes would be noticeable in just the first generation. Over hundreds and thousands of years, the humans living on those settlements would experience natural selection. People whose physiologies could better withstand the implications of very high or very low gravities would live longer, healthier lives and tend to produce more offspring. Over millennia, all humans born on Kepler 10c would be super-robust “gravity resisters”. The physical alterations might be so drastic that those humans may eventually be unable to interbreed with humans from lesser gravity planets, leading to an entirely new species of humanity.
In addition, changes to the human body will not only be caused by the environment and natural evolution: We will also force alterations to our physiologies through the application of genetic and cybernetic engineering. To adapt to a world that has a different atmospheric composition or varieties of nutrients that we normally could not metabolize, we might choose to change ourselves rather than spend decades or centuries terraforming the planet.
It will certainly be an exciting era of discovery as we turn outward to the stars. The 21st century will likely go down in history as humanity’s first true attempt at living in space.
Reprinted with permission from the author.
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