Space Colonization (SC) refers to permanent self-sufficient human habitation of locations outside the Earth.
There is much confusion about Space Colonization. SC will happen when proper technology is available - we are not there yet - just now only Exploration of near Space (SE) is possible; the international space station (ISS) has been doing a good job for almost 20 years.
In my outreach talk at Dumfries, Scotland on 3rd May, 2016, I have looked at SC and put it through the test mill of What?, Why?, Where?, When? and How? from the perspective of an inquisitive layman. I conclude that we do not yet have the technology and financial resources for SC. There are many poorly understood science and human anthropology questions - radiation protection, sub-gravity effects, psychology of living in isolation, politics of individual colonies - their interaction with each other and the Earth, economic viability of individual colonies etc.
In the following, I publish the slides of my talk with some comments added to help continuity of presentation:
Click on a slide to view bigger image:
The only way to start is by considering suitable places where colonization might be successful. These are locations nearest to the earth in our Solar System - either in orbit around the Earth or on a rocky planet
Some of the fundamental unsolved problems associated with long-term habitation in space are highlighted by a statement from Scott Kelly who returned to the Earth in March 2016 after spending 340 days in ISS.
ISS gets all its supplies from the Earth at great financial costs. Kelly's problems are personal problems related to human physiology and psychology. There are many many other issues that need to be addressed - we shall come to these later in the talk.
An object on earth is attracted by a force directed towards the centre of the earth and equal to mass times the gravitational acceleration at the earth's surface (g=9.81 m/s^2). We feel this force as our weight. ISS is on average about 415 km above earth and its distance from earth's centre is not much different than the distance when you are on the earth (6375 km). So, g in ISS should be very similar to g on earth's surface. Why, then in ISS objects are weightless - they feel no gravity:
In an orbiting satellite, the force due to its motion in the orbit (centrifugal force) balances the gravitational force due to the earth's attraction creating a zero gravity environment. At Moon, Earth's gravity force is very small due to its distance from the earth. But objects feel a gravitational force due to the Moon itself - the force is only a sixth of what it is on the earth's surface because Moon is a much smaller body than the earth is.
Private enterprise is never very far away when it comes to making money. Zero-g excites people and a company actually offers zero-g experience (lasting only about 25 seconds - repeated 20 times or so) for a cost. I show some amazing acrobatics one can do in zero-g in ISS.
Building an orbital colony seems like a good start - problem of weightlessness can be solved - people live along the rim of the colony in 1g environment. The gravity decreases as you move towards the axis of the colony; gravity being zero at the axis. This allows all sorts of recreational possibilities.
Building obital colonies will be easier than similar structures on earth as construction materials are weightless in space - they are easy to move and do not need to support much weight. Because of its smaller gravity, transporting materials from the Moon will be much easier and cheaper to use. A mining enterprise at Moon will do the trick.
Ionising radiation in space is damaging to human health - high energy particles in cosmic rays cause damage to the genetic material (DNA). On Earth, we have the atmosphere that attenuates a large part of the cosmic radiation and provides us a safer environment to live. An orbital colony or colonies on Moon or Mars will not have this protective layer and inhabitants will be exposed to dangerous levels of cosmic rays.
The Sun produces solar flares which mainly consist of high energy protons. Besides their biological effects, solar flares can cause serious disruption to electronic equipment etc. The Earth's magnetic field deflects and hence protects us from the charged particles in solar flares. Orbital colonies will, in most part be protected but colonies on Moon and Mars will not have this protection.
FOOD: Space colonies must produce their own food. The food will be mostly plant based with possible fish farming. This should not be a problem as a vegetarian diet can provide a wholesome and interesting range of food. In fact, humans have descended from the apes who in most part eat plant based food. As vegetarians, we shall only be going back to our evolutionary roots and eating what human bodies were designed to do.
Some final thoughts: In this talk I have restricted myself to a discussion of space colonization using the technology as we have at present. This is obviously a gross simplification of the subject as technology is moving forward at an exponential rate and capabilities of what we can do are bound to change very rapidly. Robotic exploration and colonization of space is an obvious extension to what I have discussed here. Robots do not require food or radiation protection or 1g environment. This will already make the design of the colonies much simpler. 3D-printing will allow a population of intelligent robots to be assembled in the colony and less material will need to be transported from the earth.
Humans present a big problem. They are competitive and love power and wealth. How will this be consistent with space colonies living in peace with each other is a question, I do not have an answer to. If the idea of space colonies is to ensure the survival of human race then this might be an unrealistic aim. What seems possible is that we can exploit the resources of space for making life on Earth more fulfilling and enjoyable. It will be best if we can start to care and cherish the wonderful planet that we have inherited. It makes no sense to destroy what we have and try to rework hostile space as our new home.
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