<http://schema.org/articleBody>
"Space colonization is something that people have dreamed about since the moon landing, and is in fact considered a priority for the future of mankind by leading scientists.\r\n\r\nUnfortunately, we\u2019ve all but ignored space colonization and the development of its technologies in recent decades, though there have been a myriad of developments that weren\u2019t intended to advance the cause that will do just that.\r\n\r\nAerospace advances, submarines that humans can survive in for months at a time autonomously and experiments like the Biodome have all led to uncovering pieces of the puzzle.\r\n\r\nIt\u2019s not a huge surprise that governments and corporations aren\u2019t investing heavily in space colonization itself. We still need to make many, many more of these ancillary but important advances before we\u2019d make any significant progress in the area. And there\u2019s that other issue \u2013 that governments and corporations don\u2019t see a need to ramp up the timeline on this.\r\n\r\nBut Stephen Hawking, one of the few physicists whose name regular people actually know, thinks differently. He\u2019s worried that until we disperse, we\u2019re in imminent danger of a catastrophic event destroying human civilization \u2013 heck, human life \u2013 for good. \u201COne we spread out into space and establish colonies, our future should be safe,\u201D Hawking once said to a BBC reporter.\r\n\r\nThere\u2019s much to consider, and the question of where we should colonize isn\u2019t even chief among them yet. Let\u2019s skip the boring stuff for the moment, though, and start there.\r\nWhere would we colonize?\r\nThere are more seemingly viable options than you might think within our solar system alone. None of them are particularly viable right now, but they all differ greatly in how much technological improvement is needed before they do become viable.\r\n\r\nMars is one of the most promising candidates. It\u2019s not too far from Earth, which is part of what makes it so promising: we occupy prime real estate that\u2019s not too far from the sun nor too close, with much variance in either direction causing catastrophic climate extremes.\r\n\r\nMars is a cold place, but it\u2019s got plentiful resources in comparison with the alternatives.\u00A0 We could extract air and water from the planet\u2019s atmosphere and ice caps, which goes a long way to improving our chances \u2013 if there\u2019s no way to harvest resources they have to be sent from Earth, and that\u2019s not particularly sustainable in the long term.\r\n\r\nMars also has plentiful minerals that could be used in the construction of structures \u2013 structures that we\u2019d be spending plentiful time in, as while Mars has air and water in extractable quantities, it\u2019s got a thin atmosphere that\u2019s not a huge improvement on sticking your head out into deep space.\r\n\r\nThe moon is another popular option, with a much shorter travel time from Earth. The presence of water was discovered and confirmed in 2009. In terms of structurally contained colonies, the moon represents the least challenging place to start, with that short travel time reducing the costs of transporting the necessary equipment and resources by a long shot.\r\n\r\nOther moons in the solar system are of considerable interest, particularly Europa (one of Jupiter\u2019s moons), which is believed to have an ocean beneath the layer of ice on its surface. There\u2019s even some conjecture that some oxygen-using marine life from Earth could survive in that ocean (if it exists).\r\n\r\nMercury is very similar to Earth\u2019s moon and is thus another candidate, although its proximity to the sun means the only viable colonies would need to be built on the planet\u2019s polar regions \u2013 temperatures during the day on the rest of the planet are far too extreme. It\u2019s a safe guess that this is somewhere we might expand once we\u2019ve already got a few colonies under our belt.\r\n\r\nThat\u2019s not to say that Mercury lacks advantages over the moon. Solar power is easier to collect, it has more gravity than the moon, and perhaps the greatest incentives for the corporations of the future that will doubtless beat government to such endeavors is the presence of incredibly valuable minerals on the planet\u2019s surface.\r\n\r\nVenus, the closest planet in the solar system to Earth, has an equatorial temperature of 500 degrees Celsius, though that hasn\u2019t stop scientists and writers from thinking of ways we could colonize this furnace. The more realistic of these theories involve colonization on some sort of floating structure in the upper atmosphere where temperatures are more manageable. Similar approaches to colonizing gas giants like Jupiter are taken, with floating cities a common idea.\r\n\r\nAsteroid colonization is decidedly tame next to these ideas, and makes particular sense in the context of asteroid mining in the solar system\u2019s main asteroid belt, located between Mars and Jupiter. One idea uses Ceres, the dwarf planet in that belt, as a sort of hub for colonies on the other asteroids \u2013 from here, transportation for minerals to our inner colonies including Earth could be more easily arranged.\r\n\r\nFree-standing habitats are theoretical structures built to serve as a home for humans that isn\u2019t attached to any existing body. In these space colonies, humans would be able to hone the technologies required to make such an environment truly sustainable in advance of vessels intended to carry humans through deep space over generations.\r\nStructures &amp;amp;amp; Terraforming\r\nAt the moment, our best bet for colonization is to design structures capable of both supporting human life and extracting resources from the planets, satellites or asteroids on which they\u2019re established.\r\n\r\nWe\u2019ve made some progress in figuring out how to survive in such structures for extended periods of time. Submarines and their crews often don\u2019t surface for months at a time, and it\u2019s hoped that one day we can create structures in space that will be permanently sustainable. But perhaps the most sustainable way is to turn another body into an Earth-like habitat, with a similar atmosphere, water bodies, climate, and the ability to grow and raise food sources.\r\n\r\nThis would give humanity far more room to work with, unlimited by the speed with which specialized structures can be created. And in several billion years when the sun\u2019s increase in luminosity causes Earth\u2019s oceans to become evaporated and other more painfully disturbing things to occur, a terraformed Mars would give us several thousand years of extra time to figure out what\u2019s next for humanity.\r\n\r\nThe problem with terraforming is that, depending on the extent of the terraforming done, the process would apparently take between hundreds of years and hundreds of thousands of years. On top of that, massive sums of money and incredible resources would be required for such a project, to the point where even the richest countries would need to help each other to achieve the goal.\r\n\r\nA more achievable goal would be the development of biodomes that cover large areas, big enough to hold a city\u2019s worth of people. These domes make it easier to control a variety of factors, such as creating pressurized atmosphere and preventing it from blowing off into space. It\u2019s likely we\u2019ll see this approach taken first, terraforming portions of a planet until a series of biodomes make much of it habitable. We have reportedly had the technology required to create such a structure for fifty years.\r\nDeep Space Colonization\r\nThe question of which local bodies we could colonize, terraform and otherwise adopt is an interesting one, but to truly preserve humanity as Hawking mandates we need to move beyond our own solar system.\r\n\r\nBut we\u2019re a long, long way from figuring this problem out.\r\n\r\nTrying to find a habitable planet isn\u2019t even the biggest concern. Getting there is. Interstellar travel is a tricky topic even when it comes to small craft. Moving the equipment, resources and humans needed for a colony over interstellar distances, let alone in our own solar system, is a tricky problem indeed.\r\n\r\nPropulsion is the biggest, though not the only, setback.\r\n\r\nAt the speed of Voyager 1, the fastest craft we\u2019ve sent into space, it would take over 70,000 years to get to the Alpha Centauri system \u2013 the closest star system to ours. Modern technology could do somewhat better, though not significantly enough to make it close to feasible.\r\n\r\nNuclear pulse propulsion is a theoretical propulsion system that, when technology advances to the point we\u2019re able to actually build such a system, could even get us to those nearest stars in centuries instead of millennia. But that\u2019s still longer than a lifetime, thus still requiring generational ships. It\u2019s much easier to expect that a ship on a trip of a few hundred years will arrive safely with the departing crew\u2019s children alive and well.\r\n\r\nA generational ship spanning 70,000 years is another story: recorded human history is a fraction of that time and we\u2019ve already shown that we\u2019re not particularly good at looking out for the continuing prospects of our species.\r\n\r\nEven if we can cut propulsion time down to reasonable levels \u2013 a couple of generations at best \u2013 and find a habitable planet, building a generational ship won\u2019t be easy. It\u2019ll need to support said colonists in a sustainable fashion over the centuries and it\u2019ll need to overcome some significant engineering challenges in order to be large enough.\r\n\r\nIf you grew up on science fiction as I did, it can be a bit of a downer to see how far beyond current capabilities colonization beyond the solar system or even inside of it will be. But it\u2019s still exciting to think about, and with any luck, our descendants will be living it."^^<http://www.w3.org/2001/XMLSchema#string>
<http://thenextweb.com/insider/2011/06/26/what-would-colonization-of-the-final-frontier-look-like/>