Now that I have a bit more time, I’ll continue with my long and painfully drawn out discussion of the ACES conference. 🙂
After the first panel, and a quick lunch, but before the next panel, there was another keynote speaker, Dr Joan Vernikos. I got to work with her during a breakout Dr Vernikos is a space life sciences researcher with many years of experience working with astronauts, and researching the effect of microgravity on the human body. As she pointed out, one of the best ways to study the effect of gravity on a human body is to study what happens when the body is no longer subject to gravity.
She described in her talk some of the things that happen to people exposed to long-term microgravity. Only some of this was new to me, but since many of you probably haven’t been corrected by Henry Spencer as much as I have, some of it might be news to you. Anyhow, when you’re in free-fall, the fluids in your body redistribute themselves, since gravity is no longer trying to pull them down into your feet. The end result is that your head and upper body end up with a lot more fluid in them than normal. Some sensory organs in your neck notice after a while what appears to be too much fluid in your body, which triggers a mechanism causing you to need to pee a bunch, until the fluid level in your head is back down to the level it would be on earth. The problem is, at this point your body has actually started dehydrating itself! Talk about the danger of sending false signals.
Anyhow, this and other related effects cause a slew of other biological effects to start occuring rather rapidly. For instance, bones don’t absorbe calcium as well. Muscles develop a resistance to insulin, which decreases their ability to absorb blood sugar, which in turn causes the muscles to atrophy. Sleep problems have been reported extensively, in spite of perfectly normal EKG readings. You don’t wake up a bunch or something like that, but when you do finally get up, you feel as though you hadn’t slept at all! The immune system gets suppressed. And all of that is before you start looking at the effects due to not having to hold up as much weight! It also appears that to-date most exercise in space has proven more or less useless. It helps a little, but the key problems appear not to be related to not using your muscles, but due to the body’s actual response to lack of gravity!
After a sufficiently long flight, there are other effects. Stuff like lack of balance, impaired coordination, fainting, feet hurting, nocturnal diuresis (having to pee a bunch at night), reduced stamina, more fragile bones and heart, etc.
There are some additional problems that while not explicitly verified there is some evidence for. Stuff like wounds wounds and bone damage taking longer to heal, decreased or changed effectiveness of drugs and nutrients, vision changes, cognitive and emotional problems, and our favorite: gastrointestinal problems.
[Note: most of these effects take a while to start occuring. Suborbital flights aren’t long enough for any of these to really start taking place, and orbital flights of a few days probably are also insufficient to run into most of these problems. We also really have no clue what the result of long-term exposure to gravity levels between zero-g and 1g are, we just have no real data. I think that adding even a little gravity will be likely to drastically reduce many of the effects of microgravity on the body, but there are many others who disagree.]
One of the things that was noticed fairly early on in the space age (by both Russians and the US) was that many of the symptoms of extended exposure to microgravity were very similar to the effect of long-duration bed rest. She also pointed out an interesting correlation to the effects of aging. The key difference being that the effects of microgravity and bed-rest were reversable, which kind of begs the question if aging effects might be reversible, preventable, or at least delayable.
She then went on to some of her hypotheses on the matter. She thinks that by taking greater advantage of gravity (through better posture, standing up instead of sitting when you can, and a bunch of other ideas), that some of these effects may be decreaseable. She suggested that there may be a correlation between more and more leisurely jobs (which tend to have people sitting down at a desk for long durations) and the higher occurance of aging related symptoms at younger and younger ages. She then suggested that in the future we may see hypergravity gyms. Stuff like man-powered centrifuges and the like.
All in all a very interesting talk, that I’m probably butchering a bit. She has a nice book out on the topic, though I didn’t pick one up. Might be worth checking out.
Jonathan Goff
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Late to the discussion.
Re: hypergravity on Terra.
See http://it.wikipedia.org/wiki/Pista_centrifuga for one way to go. Scuderi uses a curve of revolution to vary both g and v with r, but a simple cone with slope alpha has an effective acceleration of g/(cos alpha) for any radius, with speed
sqrt[(g * r * tan alpha)]. For 30 degrees, that is an extra 15%, with v(3 m) = 4.1 m/s.
The Skylab 500 gave the astronauts partial gravity but it upset the solar telescope tracking. (Homesteading Space: The Skylab Story)
With sufficient space, an astronaut could bounce between walls with a half-flip. This is a heavy workout, so add mini trampolines. The acceleration is intermittent (beware resonance with solar panels) and safety is a problem.
MBM