"But then more results started coming back. Not only do astronauts come back with weak muscles and frail bones… But they also suffer from skin thinning, atherosclerosis (stiffer arteries), resistance to insulin and they suffer from loss of vision due to cataracts many years earlier than expected given their chronological age. These symptoms look a lot like skin aging, cardiovascular aging, age-related diabetes and so forth. In fact, it is pretty accurate to say that astronauts age at an accelerated rate."
John Glenn, Neil Armstrong, Buzz Aldrin, Michael Collins and Edgar Mitchell all lived beyond the average life expectancy of American males born when they were born.
Our bodies have incredibly complex feedback loops and we evolved here, with a constant 1G of gravity.
It's not surprising to me that exposure to Zero-G can have long lasting and unexpected consequences.
At the extreme edge, the average age of people in nursing homes is much older than life expectancy at birth. That does not mean nursing homes are good for you.
These are astronauts the commenter remembers. To be accurate, check against all astronauts from that time period.
People who are healthiest in their mid to late 30s being more likely to live into old age than those who are not is a plausible explanation for what I have observed.
I'd imagine astronauts are more likely than the overall population to have good healthcare, good pensions, etc. Helps live longer.
I would love to hear about some of these.
[0] I'm using "Feel" in a relative context, since muscle weakness/wasting will not feel good once you're back in a non-weightless environment.
I expect the disorientation, nausea, etc., would outweigh any short term muscle-feel effects. For how weightlessness feels: http://science.howstuffworks.com/weightlessness2.htm
I wonder what they mean by that. Are astronauts explicitly banned from eating fast food, and somehow monitored? Or are they just less likely to eat fast food, since they pay close attention to their fitness and health?
[1] http://www.bis-space.com/2014/03/04/12501/uk-space-life-and-...
[2] http://www.ukspacelabs.co.uk/about/5-strategy-r-d-themes
Perhaps the effect is due to lack of grounding.
I imagine this question won't be seriously answered until we have an artificial gravity system.
"They are also followed medically more closely than just about anyone on Earth: they don’t indulge in regular fast food."
Have you guys heard about the entire field of study that is aerospace medicine? I’m taking a course on it this semester (I’m a masters student in aerospace engineering)–let me summarize some of the problems that your body goes through during space travel.
Humans spend about 70% of their time either standing or sitting. That means the human body is optimized for a hydrostatic pressure gradient like the one illustrated here (http://wiki.sdstate.edu/@api/deki/files/999/=1-BP_Change.png). Blood pressure is much higher at your feet than at your head. In space, however, there is no gravity to produce this gradient, so the cardiovascular system equalizes its pressure. That’s why astronauts suffer from “puffy face” (higher-than-usual fluid pressures in head) and “chicken legs” (lower-than-usual fluid pressures in legs). In their first couple days in space, astronauts lose about 1L of leg volume from each leg.
The CV system relies on internal pressure sensors to figure out how to operate, and the new pressure distribution confuses it. Astronauts lose a lot of blood plasma–it sort of ends up absorbed into the surrounding tissues. This increases the relative concentration of red blood cells, which triggers the body to slow down production of new ones. Also, the heart atrophies because it doesn’t need to pump as hard to move liquid around the body.
When you come back from space, your body needs to rapidly readapt from microgravity to one gee. It is not very good at doing that. That’s why 63% of astronauts are unable to stand for ten minutes straight just after their return from short-duration space missions (see video: https://www.youtube.com/watch?v=TPDST7EePXQ).
There are other problems: the cells that are constantly building and destroying your bones fall out of alignment when you’re in microgravity, causing astronauts’ bones to change structure in a way that looks a lot like accelerated aging. Why? Not clear, but possibly related to the lack of repeated loading, as happens when you stand/walk in normal gravity. Astronauts end up with huge concentrations of calcium in their blood, which causes kidney stones. Astronauts in space average around 4 hours of sleep per night, and very few of them eat enough calories to maintain their body weight, so they lose muscle mass.
Aerospace medicine is about half medical studies of astronauts and half studies of people on earth. It turns out that you can make most of these body changes happen by having people lie on their backs with the bed tilted down six degrees (head downward). Fascinating field. If you want to know more, I recommend the textbook “Space Physiology” by Jay Buckey (amazon link here: http://smile.amazon.com/Space-Physiology-Jay-C-Buckey/dp/019...).
