The Human Body May Not Be Cut Out For Space 267
Hugh Pickens DOT Com writes "The human body did not evolve to live in space, and the longest any human has been off Earth is 437 days. Some problems, like the brittling of bone, may have been overcome already. Others have been identified — for example, astronauts have trouble eating and sleeping enough — and NASA is working to understand and solve them. But Kenneth Chang reports in the NY Times that there are some health problems that still elude doctors more than 50 years after the first spaceflight. The biggest hurdle remains radiation. Without the protective cocoon of Earth's magnetic field and atmosphere, astronauts receive substantially higher doses of radiation, heightening the chances that they will die of cancer. Another problem identified just five years ago is that the eyeballs of at least some astronauts became somewhat squashed. 'It is now a recognized occupational hazard of spaceflight,' says Dr. Barratt. 'We uncovered something that has been right under our noses forever.' NASA officials often talk about the 'unknown unknowns,' the unforeseen problems that catch them by surprise. The eye issue caught them by surprise, and they are happy it did not happen in the middle of a mission to Mars. Another problem is the lack of gravity jumbles the body's neurovestibular system (PDF) that tells people which way is up. When returning to the pull of gravity, astronauts can become dizzy, something that Mark Kelly took note of as he piloted the space shuttle to a landing. 'If you tilt your head a little left or right, it feels like you're going end over end.' Beyond the body, there is also the mind. The first six months of Scott Kelly's one-year mission are expected to be no different from his first trip to the space station. Dr. Gary E. Beven, a NASA psychiatrist, says he is interested in whether anything changes in the next six months. 'We're going to be looking for any significant changes in mood, in sleep, in irritability, in cognition.' In a Russian experiment in 2010 and 2011, six men agreed to be sealed up in a mock spaceship simulating a 17-month Mars mission. Four of the six developed disorders, and the crew became less active as the experiment progressed. 'I think that's just an example of what could potentially happen during a Mars mission, but with much greater consequence,' says Dr. Beven. 'Those subtle changes in group cohesion could cause major problems.'"
Re:Roll on! (Score:5, Interesting)
I've been wondering why they don't at least do some animal studies on this centrifugal "gravity" idea. I mean how tough would it be to rig a rat cage and counterweight to rotate at some fraction of 1g? Put some critters in there for a few months, and take a control group along for the same duration, and see what happens. It probably wouldn't even cost very much, but could yield some key insights.
Re:Space or Lack of Gravity? (Score:5, Interesting)
That is a good idea in theory, but artificial gravity by rotation has a rather big problem involved: We're not 1 inch tall. Gravity by rotation is dependent on velocity. And depending on how "big" that wheel is, that velocity may be considerably different at the floor and 6 feet up.
In other words, if that wheel is too small and you spin it too fast (to get to that 1g you want), you'd be nauseated to the extreme.
I don't have the exact numbers in my head right now, but I do distinctly remember that the required size was somewhere in the vicinity of "friggin' huge" to avoid such a fate.
squashed eyeballs (Score:5, Interesting)
I have no trouble believing the human eye does not do well in zero gravity. Case in point, I have a bookstand that holds a book upside down, to read lying down in bed. If I read for an hour in that position, my vision becomes all blurred, something that doesn't happen when I read with my head upright or tilted backward at a slight angle.
I'm pretty sure proper vision depends on gravity pulling the eyeball the direction the eyeball is used to to maintain its shape, i.e. down.
Re:Roll on! (Score:4, Interesting)
Re:Roll on! (Score:4, Interesting)
You'll need accelerometers mounted in various places, and some moveable counterweights along the spokes to adjust for changes in weight balance , preventing wobble.
Or you need the ship to be massive enough to where a few humans on one side of the ring don't amount to a hill of beans.
The next step to massive exploration of space is asteroid mining. We can't even build ships big enough.
Re:Roll on! (Score:5, Interesting)
Dealing the coriolis and tidal forces might be worse than the problem it's trying to solve, unless you have a really enormous centrifuge.
Or two modules with a long tether [wordpress.com] spinning round their mutual centre of gravity
Re:A tethered design more realistic in near term (Score:5, Interesting)
You'd still need some sort of centrifuge, to stave off all the muscular and skeletal side effects of zero G; but tampering with the inner ear to prevent the subject noticing the various imperfections associated with a fairly small centrifuge might well become doable with small computerized implants in the relatively near future...
Re:Space or Lack of Gravity? (Score:4, Interesting)
According to someone else's comment just above, the absolute minimum size required for most humans to be comfortable is 100m radius and rotation rate of 3 rpm. Going up to 500m radius and 1rpm would make the habitat comfortable for almost everyone.
Sounds like a lot, but we build much larger structures that this all the time here on Earth which are capable of withstanding the forces of storms at sea, battering waves, etc.; they're called "ships". The biggest ones are about 400m long. Something built for space doesn't need to be remotely as rugged as an aircraft carrier, since there's no gravity or other forces to deal with besides those caused by rotation and propulsion, so it really shouldn't be that hard to build something that size if we put our minds to it and actually dedicated serious resources to the task instead of sitting around and debating Creationism.
Clifford Simak predicted this (Score:4, Interesting)
Re:KISS (Score:2, Interesting)
If you need a flexible and functional exploration machine it is hard to beat a human on site.
A journalist asked a geology professor about the work done by the Mars rovers. He summed it up by saying that all last half century of geology by robot was amazing, but just about what a trained field geologist could have done in an afternoon if actually there.
Robot's are claw hammers that help the person who prepared to look at rocks smash rocks better. Sometimes you don't need a hammer and if the robot wasn't prepared for this it falls on us, people, not the robot to make due.
Humans have crawled over almost every square inch of the Earth, including some - like the Challenger Deep and your Mom's house - equal to or more difficult to get into that freefall in a high radiation environment. Sometimes exploring a new place has changed us more than we changed it, but this is just another environment. If just to get away from the other idiots where we come from, we will go there.
Re:Roll on! (Score:4, Interesting)