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Human bodies : * require a constant supply of oxygen. Which is available effectively nowhere except deep inside gravity wells. * require a constant supply of

by waps 12y ago

Human bodies : * require a constant supply of oxygen. Which is available effectively nowhere except deep inside gravity wells. * require a constant supply of water. Which is available effectively nowhere. H may be everywhere, but O is nowhere convenient. * require G-forces to be between 0.8 and 1.2 for long term survival. Can tolerate very brief exposure up to about 4G. This means the vast majority of planets are effectively uninhabitable just for that reason. And harshly limits the maneuvers possible to get there. * require a sun-like source of radiative energy with a certain minimum intensity (one of the reasons people can't survive on Mars without additional UV exposure) * require the presence, in small quantities, of half the elements with an atomic number up to 26, and several found further on. H, C, N, O, Na, Mg, Al, S, Cl, K, Ca, Fe, and I. Some of these are not very common, and they may be very hard to find. Not finding them first means it becomes impossible to have kids, increased occurrence of things like cancer, and a few years later it becomes lethal. * require gravity. Which is massively inconvenient for operating ... well, anything really * require radiation shielding against solar radiation for long term survival that requires about a hundred kilometers of atmosphere or several inches of metal (if you're to survive long term, for short excursions less isolation can be acceptable, also in Low Earth Orbit (like ISS) you're still partially shielded by the earth) * require radiation shielding for charged particles that is provided by the earth's magnetic field, but requires metal barriers in outside of those fields * require the sun's plasma barrier around the solar system to weaken interstellar background radiation to the point that the earth's atmosphere/reasonable thickness metal can actually stop it. * require to be inside the galaxy, again to weaken certain types of radiation * require a minimum distance to any supernova explosion of around 50 light years to survive (or yet more shielding) * require to be in groups of at least 50 for long term survival (or we won't have enough gene variation and die off over time), even though short excursions can use a limited number of people. This is the low end of the estimates. * require to be in groups of 2-3 people at least even for short term excursions or there will be severe psychological consequences * require the presence of large masses of bacteria to fulfill certain bodily functions the human body can't actually do itself (best - but not only - example being digestion) * require the presence of bacteria outside of the body to create compounds that we can't make ourselves. Some of these cannot be stored for any length of time, you need to take bacterial colonies or, better yet, plants + bacterial colonies with you and let them grow. This isn't a complete list by any means. Human bodies will never go very far from Earth.

a8da6b0c91d 12y ago
> Human bodies will never go very far from Earth. It is possible with space elevators and a series of Biosphere 2 style experiments. A series of five and ten year experiments can prove the feasibility of building hermetically sealed nuclear powered habitats. With space elevators they can be replicated outside the gravity well in space, spinning at 1G and properly shielded from radiation. Nano tech developments make space elevators seem less and less crazy. It is not crazy to expect to happen in the next 40 years. The thing to do is hermetically seal off some deep down mines with nuclear reactors and 30 people for 10 years and prove it can be done.
- IndianAstronaut 12y ago
  They have already tried to seal off humans to see if they could survive in a closed habitat for years. They failed. Until we figure out a way to generate food without the use of plants and animals, we cannot explore space. The overhead of having to maintain plants and animals for food is just too great to make sustainable living elsewhere in the solar system feasible.
  - a8da6b0c91d 12y ago
    There was one fairly low budget attempt. Nobody ever said it was going to work the first time. I can imagine it taking 25 years to iron out all the kinks. It's not like people figured out reliable trans-oceanic voyaging and navigation in a couple years. It was a long processes.
  - xenophonf 12y ago
    If everybody stopped trying to do something the first time they failed, no one would do anything or learn anything. Heck, science is all about systematically and methodically failing - that's what the null hypothesis is all about! I almost wrote that we probably won't have permanent outposts in space within any of our lifetimes, but that isn't strictly true, is it, what with Skylab, Mir, and ISS? So let me posit that we will probably never see self-sustaining space habitats (whether in orbit around Earth or on some other body in the Solar System) within our lifetimes, nor within our children's lifetimes. That doesn't mean it isn't a worthy (or feasible) goal. Mankind has wondered about traveling to the moon for hundreds of years (if not thousands), and only recently has it become possible. Living somewhere other than Earth isn't really all that different, insofar that it is an engineering problem and not a scientific one, and unless some apocalyptic disaster strikes us, we have nothing but time in which to figure it out.

by waps 12y ago

a8da6b0c91d 12y ago

> Human bodies will never go very far from Earth. It is possible with space elevators and a series of Biosphere 2 style experiments. A series of five and ten year experiments can prove the feasibility of building hermetically sealed nuclear powered habitats. With space elevators they can be replicated outside the gravity well in space, spinning at 1G and properly shielded from radiation. Nano tech developments make space elevators seem less and less crazy. It is not crazy to expect to happen in the next 40 years. The thing to do is hermetically seal off some deep down mines with nuclear reactors and 30 people for 10 years and prove it can be done.

IndianAstronaut 12y ago
They have already tried to seal off humans to see if they could survive in a closed habitat for years. They failed. Until we figure out a way to generate food without the use of plants and animals, we cannot explore space. The overhead of having to maintain plants and animals for food is just too great to make sustainable living elsewhere in the solar system feasible.
- a8da6b0c91d 12y ago
  There was one fairly low budget attempt. Nobody ever said it was going to work the first time. I can imagine it taking 25 years to iron out all the kinks. It's not like people figured out reliable trans-oceanic voyaging and navigation in a couple years. It was a long processes.
- xenophonf 12y ago
  If everybody stopped trying to do something the first time they failed, no one would do anything or learn anything. Heck, science is all about systematically and methodically failing - that's what the null hypothesis is all about! I almost wrote that we probably won't have permanent outposts in space within any of our lifetimes, but that isn't strictly true, is it, what with Skylab, Mir, and ISS? So let me posit that we will probably never see self-sustaining space habitats (whether in orbit around Earth or on some other body in the Solar System) within our lifetimes, nor within our children's lifetimes. That doesn't mean it isn't a worthy (or feasible) goal. Mankind has wondered about traveling to the moon for hundreds of years (if not thousands), and only recently has it become possible. Living somewhere other than Earth isn't really all that different, insofar that it is an engineering problem and not a scientific one, and unless some apocalyptic disaster strikes us, we have nothing but time in which to figure it out.