The recent experiment with astronaut Scott Kelly and his twin Mark, studying their physical differences after Scott spent a year aboard the International Space Station (ISS), has provided even more evidence that the human body does undergo significant changes when in prolonged microgravity. In the case of Scott:
Studies of the twins’ telomeres, the caps on the ends of their chromosomes, showed that during spaceflight Scott’s telomeres grew to be longer than his brother’s. “That is exactly the opposite of what we thought,” says Susan Bailey, a radiation biologist at Colorado State University in Fort Collins… Once Scott returned to the ground, the length of his telomeres returned to his pre-flight levels relatively quickly. The scientists are working to figure out what this means, and are running a separate study of telomere length in ten unrelated astronauts that, when completed in 2018, may shed more light on how spaceflight affects telomeres.
Other effects of prolonged microgravity have included well-known issues such as bone and muscle loss, and the more recent revelation of a buildup of fluid in the eye, degrading eyesight and potentially causing blindness over time.
Clearly there is still a lot to be learned about the prolonged effects of microgravity, how well the body can recover from those effects when reintroduced to gravity, and how well the medical industry can speed up the recovery process. In the meantime, a lot of discussion is being carried out on ways to prevent the damage from being done in the first place.
One of the potentially most effective solutions is to provide ways for astronauts to spend a significant amount of time under gravity between periods of microgravity. The idea is for more frequent periods in gravity to induce the body to start internal recovery on a more continual basis, to help it fight off the deleterious effects of microgravity more or less ’round the clock.
I was thinking of this when I wrote my novel Factory Orbit, years ago. In it, a factory and research facility was constructed in Earth orbit (pictured at right), manned by machinists and scientists, and a support staff on board with them. Although the factory and research areas—the large central cylinder—were operated in microgravity (0-gee), the living and sleeping areas of the facility—the ring of interconnected former space shuttle fuel tanks—were rotated around the factory at the equivalent of 1 Earth gravity (1-gee). Just like on Earth, workers spent approximately 1/4 or 1/3 of their day working in the factory and research cylinder, the rest living, recreating and sleeping in the off-duty living and sleeping areas. So their bodies spent most of the time under 1-gee, then worked in 0-gee for 1/4 to 1/3 of their day, and returned to 1-gee.
I postulated that this limiting to 1/4 – 1/3 of a day’s cycle in microgravity, and the rest of the day in full gravity, would be enough to mitigate the effects of prolonged microgravity to next to (or completely) nothing, and remove the need for medical assistance or significant physical rehabilitation to recover from a prolonged stay in space.
Since I’ve written Factory Orbit, I’ve found people online debating the amount of time that would be required in a day’s cycle to mitigate microgravity’s effects, some thinking that as little as a few hours in 1-gee or even less than 1-gee would be enough to do the job. I suspect a longer period than 1-2 hours would be required; maybe it is less than the 16-18 hours I suggest in my novel; maybe less than 1-gee would be sufficient, or maybe shorter periods at more than 1-gee would work; but then, no one’s tested this yet, so who knows?
I think the theory is worth significant study, and I’d expect to eventually see some space agency test it out: Building a space facility with two sections, one that rotates to simulate 1-gee, the other maintaining 0-gee; rotating astronauts between the sections for specific, recorded periods, for perhaps a year; then returning them to ground (or testing them in orbit) to see how their bodies react over time.
Not only should it provide significant data on how the human body handles microgravity, but the need to build a part-gravity, part-microgravity facility should teach us a lot about the future engineering needs of such structures, which will probably be a big part of future space facilities.
Since it is my firm belief that we can put the space in near Earth orbit to positive use, researching and creating new compounds and materials, finding new and better ways of producing and running heavy machinery in microgravity… I think it behooves us to find ways of putting workers in orbit without endangering their physiology. Thorough testing of the effects of space on the human body should be our next priority in space exploration.
Note: Factory Orbit is not presently available for purchase. I’ve been considering a rewrite to update the book, if I ever get a mandate to do so (or if someone just offers me a decent paycheck to do so).