In the 1970s when gigantic in-space colonies similar to the one depicted in the recent movie Elysium were proposed, the obvious question was how could such behemoths possibly be affordable when it had cost billions just to send a handful of people to the Moon. That question still remains up front today for anyone proposing such free flying islands in space.
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Those who were working on such colony designs in the 70s were quite aware of that question and were counting on three factors to make the colonies affordable:
- A big drop in space transport costs once the Space Shuttle started flying
- Get most materials from the Moon whose low gravity allows for relatively easy launch into space, e.g. can literally throw material into orbit with a mass driver
- Earn income from solar power stations built by colonists to supply power to earth.
Unfortunately, the Shuttle, which was far from the robust and fully reusable vehicle initially proposed, failed to lower the cost of getting to orbit by even a modest amount.
Without low cost launch, it has been impossible get back to the Moon in an affordable manner and to build up an infrastructure there that could one day support construction of habitats in orbit.
Space based Solar Power remains a popular cause among many space advocates but it also remains a distant dream as long as space transport costs are so high. (I also expect that it’s more likely that space settlers will earn their keep via other commercial services such as off-shored digital services (e.g. software development) and space tourism, which is what many island economies on earth rely on.)
Fortunately, launch costs may finally start to fall significantly as NewSpace companies like SpaceX begin to make progress towards fully and rapidly reusable launch vehicles. (E.g. see a SpaceX design here and a prototype here.) The propellant cost for a typical expendable rocket are less than half a percent of the total cost of putting an object into orbit. The rest comes from throwing away the rocket each time. So cost reductions of a factor of 50 to 100 are not out of the question.
However, even such huge reductions in launch costs leave tremendous challenges to creating a construction infrastructure in space that can build something as big as a habitat to provide a comfortable environment for thousands of people. Another factor is essential to making large scale space construction feasible – advanced robotics.
It just isn’t practical due to radiation, logistics, and other issues to expect to see crews of humans assembling large structures in space. Most such work will have to be done by robots working autonomously as well as via teleoperation by humans who could reside nearby in radiation protected habitats.
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Rapid progress is being made in robotics in general and specifically for space as well. See, for example, the satellite servicing demonstrations on the ISS of teleoperated robotic systems. And just last week, the company Tethers Unlimited won a NASA grant to continue development of the SpiderFab, a robotic system that also employs 3D printing to build kilometer size structures in space.
![SpiderFab_MOST[1]](https://i0.wp.com/hobbyspace.com/Blog/wp-content/uploads/2013/09/SpiderFab_MOST1.jpg)
SpiderFab here assembles a large solar panel. (Tethers Unlimited)
(See as well this discussion of using a system like SpiderFab to build large space structures: Inflatable space stations, Reusable rockets and Spiderfab for the 2020s – NextBigFuture.com.)
It can be amazing to watch a construction project go from a muddy foundation to a brilliant tower reaching the sky. On a given day the progress looks so meager. Yet over a finite time we see that it really is possible to build a gigantic structure just by many small incremental steps by a lot of workers.
Similarly, it is in fact possible for hundreds or thousands of robots working 24/7 to build a really big structure in space in a finite time. Once such an infrastructure of robotic construction is established, we could see rapid development of the Moon and the whole cislunar system.
I was with you right up until “rapid development of the Moon”.
If we can bring large amounts of material near the Earth robotically, and build large structures near the Earth robotically, why would rapid development of the Moon (or Mars – don’t want to leave the Mars guys out) be a goal?
It seems to me that, as O’Neill pointed out, the Moon is just a source of material, possibly only after we tap the millions of metric tons available from NEOs.
Even if there turns out to be little interest in large settlements on the Moon, a fairly extensive infrastructure will be needed there to obtain and deliver building materials, water, etc.
I expect there will always be many people who want to visit the Moon and that will also require infrastructure to accommodate them.
Furthermore, the natural diversity in human interests will result in a diversity of places where people will live. E.g. no matter how fervently Californians and Texans believe that their state is the best place in the world to live, there will always be those who prefer, say, Minnesota or Alaska. I expect there will always be people who prefer to live on the Moon (or Mars) to living in an in-space habitat.
NEOs certainly offer another source of raw materials and they may turn out to be easier to exploit than the Moon. However, there are complications. If you want materials to build in-space habitats in the cislunar region, getting materials from the NEOs may be non-trivial. Most NEOs are only near the earth for brief times when their orbits are close to each other. Perhaps, as in the Deep Space Industries graphics, a habitat could be built next to an asteroid and then moved. However, there is bound to be a significant need for misc goods and services from earth for the construction and so it would be convenient to be near earth. Too early to say how these things will balance out.
We are currently in a single point failure mode for prevention of the development of space habitats.
ANYTHING that crashes, or even seriously reduces, the cost of freight to orbit removes the sole significant blockage.
Would it surprise anybody to learn there are at least four groups targeting this to my knowledge, and I am not totally well informed on this. (My bet is closer to 10, but any one succeeds and that’s the game).
Yours
Ed Wilson
If you build on the Moon you don’t need to ‘Keep it on station’. Much cheaper. 1/8th g. Makes building easier, tools stay put, wheels work, the floor stays down. The problems with humans in 0 g are also avoided properly, it has yet to be tested, but my bet is 1/8 g won’t be as hard on the body for long term stays. Our system needs to know where down is for long term stays. Trust me.
The same concepts will work, even better.
I don’t know of anyone promoting settlement in microgravity habitats. The point with in-space habitats is that you can rotate the structure to generate up to 1 g spin gravity. Perhaps lunar gravity will turn out to be sufficient for good health but it also may turn out that even Mars gravity is insufficient for good health, particularly with regard to having and bringing up children. Without children, it’s a base and not a settlement.