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Hawking the Moon and Mars

  1. Apr 23, 2008 #1

    wolram

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  2. jcsd
  3. Apr 23, 2008 #2
    Bone loss is an issue for tourists. Is it also an issue for colonists?
     
  4. Apr 23, 2008 #3
    cost?----probably less than the bush-cheney war
     
  5. Apr 23, 2008 #4

    wolram

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  6. Apr 23, 2008 #5

    wolram

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    The Wiki article states that (rigorous exercise) would be necessary.
     
  7. Apr 23, 2008 #6
    Does it say why it would be necessary?
     
  8. Apr 23, 2008 #7

    mgb_phys

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    I imagine it's the 1year trip in zero G that you would lose enough muscle and bone mass to be a problme when you arrive at Mars, even though it only has 1/3g.

    Perhaps America is evolving into a race suitable for Mars - it's not an epidemic of obesity it's a trippling of mass ready for a 1/3g enviroment!
     
  9. Apr 23, 2008 #8

    wolram

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    I have not read all the physical changes low gravity causes, but some for zero gravity are muscle loss, bone loss, chemical imbalance and even some changes in the brain, but these are for zero gravity and in a shielded space craft, not low gravity on the Moon, i can only guess that some changes would be proportional to gravity ratio.
     
  10. Apr 23, 2008 #9
    Muscle loss and bone loss are issues for tourists. Are they also issues for colonists?
     
  11. Apr 23, 2008 #10

    wolram

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    Like i have said, i have read nothing about physical changes in low gravity, apart from the Wiki article , which suggests rigorous exercise would be needed to may be counteract bone loss.

    From the article.

    There is continuing uncertainty over whether the low (one-sixth g) gravity on the Moon is strong enough to prevent detrimental effects to human health in the long term. Exposure to weightlessness over month-long periods has been demonstrated to cause deterioration of physiological systems, such as loss of bone and muscle mass and a depressed immune system. Similar effects could occur in a low-gravity environment, although virtually all research into the health effects of low gravity has been limited to zero gravity. Countermeasures such as an aggressive routine of daily exercise have proven at least partially effective in preventing the deleterious effects of low gravity.
     
    Last edited: Apr 23, 2008
  12. Apr 23, 2008 #11

    Astronuc

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    Somewhat. Certainly persons living extended time in zero-g would be pretty much confined to zero-g, especially if born and developed in zero-g, because skeleton and muscle would be developed for that environment.

    Once on the moon, for an extended period of years, one would be pretty much confined to the moon (or zero-g) based on the bodies adaptation to reduced gravity. When people return from ISS, I believe they are carried from the Soyuz capsule. I'm not sure what is done with those returning on STS after months in space.

    IIRC NASA has a exercise program to help prevent the astronauts from de-conditioning in space.

    The greater problem for astronauts at ISS and in STS is the ionizing radiation.
     
  13. Apr 23, 2008 #12
    Hawking said, and I quoted in my first post, that any long-term site for a human base should have a significant gravity field, because long missions in microgravity lead to health issues such as bone loss. But if bone loss is only a problem when you have a significant gravity field, then it is a poor argument in favor of one. Is bone loss a problem for permanent missions in microgravity?
     
  14. Apr 23, 2008 #13
    The reason I bring this up is that I feel we should colonize space itself, not planets and moons. It seems a waste to pay the price to escape gravity only to run back into the barn.
     
  15. Apr 23, 2008 #14

    Astronuc

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    But it's a different barn. :biggrin:
     
  16. Apr 23, 2008 #15

    wolram

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    It seems in simplistic terms, we need artificial gravity before humans go on long term space flights, or humans must adapt, how far is that in the future?
    I have read about the rotating (wheel) method for simulating gravity, but that would be huge.
     
  17. Apr 23, 2008 #16

    wolram

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    Rotating space station.

    http://www.go.ednet.ns.ca/~larry/physics/coriolis.html

    For a space station 15 metres in radius (50 feet) the station must make one revolution about every 8 seconds in order that the astronauts feel 1 g of gravitational acceleration (ie. the his/her weight would be the same as that on Earth).
     
    Last edited by a moderator: Apr 23, 2017
  18. Apr 23, 2008 #17

    Danger

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    Several 'hard' SF authors, including Larry Niven and Robert Heinlein, have postulated that space colonization will trigger a new phase of human evolution. With reduced or micro gravity, future generations will generally be taller and thinner (and weaker). I strongly suspect that micro gravity might also result in opposable big toes re-developing once feet are no longer needed for walking.
     
  19. Apr 23, 2008 #18
    How would humans need to adapt? There are already humans spending long periods in the ISS. Sure they have problems when they come back to Earth because of the bone loss. What I am trying to figure out is what problems do they face before they come down. Is bone loss an issue for them while they are still in orbit. If yes, then what are they. If not, then why should we expect that space colonists would suffer?

    Astronuc, gravity is the fire. Both barns are burning. For instance, the plan to ship materials for a Mars mission to the Moon, assemble them there and then lift off from the Moon to go to Mars is ridiculous. Assemble the materials in low space orbit and take off from there.
     
    Last edited: Apr 23, 2008
  20. Apr 23, 2008 #19

    wolram

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    Would these people still be classed as human or a subspecies?
     
  21. Apr 23, 2008 #20

    Danger

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    Depends upon the time-scale. They'd certainly be human for several generations, since the DNA wouldn't change. I'm not even sure what 'sub-species' means. To become a 'new' species, they'd have to be isolated from the rest of humanity for hundreds or thousands of years, or encounter some radical mutagenic influence such as radiation or genetic engineering.
     
  22. Apr 23, 2008 #21
    I assume that Hawking is talking about large-scale colonization. This would require structures of extremely large size, on the order of miles in diameter. A much smaller angular velocity would be required.

    I got a lot of my ideas about life in space from this book when I was 7 or 8 years old, a little over 50 years ago. Because of this book, I knew that ships for long voyages could be lofted to earth orbit for assembly and so avoid a great many problems with vehicles that lift off in gravity or atmosphere. For instance, as shown here, there is no need for an aerodynamic body. Also, ratio of payload to fuel is much higher, the need for rapid acceleration is gone, and the materials are reusable because they don't experience reentry.

    http://dreamsofspace.nfshost.com/first.htm" [Broken]
     
    Last edited by a moderator: May 3, 2017
  23. Apr 23, 2008 #22

    wolram

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    http://en.wikipedia.org/wiki/Weightlessness

    Seems we may develop a propulsion system

    Following the establishment of orbiting stations that can be inhabited for long durations by humans, exposure to weightlessness has been demonstrated to have some deleterious effects to health. Humans are well-adapted to the physical conditions prevailing at the surface of the Earth. When weightless, certain physiological systems begin to alter and temporary and long term health issues can occur.

    The most common initial condition experienced by humans after the first couple of hours or so of weightlessness is known as space adaptation syndrome or SAS, commonly referred to as space sickness. The symptoms include general queasiness, nausea, vertigo, headaches, lethargy, vomiting, and an overall malaise. The first case was reported by cosmonaut Gherman Titov in 1961. Since then roughly 45% of all people to experience free floating under zero gravity have also suffered from this condition. The duration of space sickness varies, but in no case has it lasted more than 72 hours. By that time the astronauts have grown accustomed to the new environment. NASA measures SAS using the "Garn scale", named for United States Senator Jake Garn, whose SAS during STS-51-D was so severe as to be ranked 13 on this scale.

    The most significant adverse effects of long-term weightlessness are muscle atrophy and deterioration of the skeleton, or spaceflight osteopenia; these effects can be minimized through a regimen of exercise. Other significant effects include fluid redistribution, a slowing of the cardiovascular system, decreased production of red blood cells, balance disorders, and a weakening of the immune system. Lesser symptoms include loss of body mass, nasal congestion, sleep disturbance, excess flatulence, and puffiness of the face. These effects are reversible upon return to Earth.

    Many of the conditions caused by exposure to weightlessness are similar to those resulting from aging. Scientists believe that studies of the detrimental effects of weightlessness could have medical benefits, such as a possible treatment for osteoporosis and improved medical care for the bed-ridden and elderly.
     
  24. Apr 23, 2008 #23
    If we advance to the stage where we can reach other stars, then it is natural to assume that we will evolve into a variety of species. It is unrealistic, in my opinion, to assume that they will not be antagonistic toward each other.
     
  25. Apr 23, 2008 #24
    Thanks.
    That's not enough of a reason to go to the moon if you ask me.
    Figures.
     
    Last edited: Apr 23, 2008
  26. Apr 23, 2008 #25
    Is terraforming Mars a practical concept at this point? Or would that take too long?
     
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