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#51 2018-07-10 22:31:43

From: New York, NY, USA, Earth, Sol
Registered: 2007-07-15
Posts: 2,280

Re: Self-replicating colony - a challenge but how difficult?

This is something I've thought a lot about and which I have a number of thoughts on, so I'd like to contribute them here.

1. Creating a "backup" for humanity is something that has real value...

But I don't think this is a good way to justify a human settlement on Mars or anywhere else.  I think it also has plenty of implications which are hard to think through.  We live in a world with finite amounts of human time and resources available, and we make decisions about how to apply these (ideally for the best possible use).  In order to say that we should settle Mars because it creates a backup for the human species and human civilization (or at least the one or ones that build the settlements), you need to think the following things:

  • The existence of living humans or the survival of a social genome has value that is not just inherent, but very large

  • That for whatever amount of resources you want to dedicate to the settlement project (possibly hundreds of billions of dollars or more!) settlement of another planet has the highest possible expected value of preserving that.  So, for example, let's say settlement reduces the probability of total destruction by a factor of 10 (settlements fail sometimes, after all, and the sudden end of interaction with Earth would be a substantial blow even if you have planned for it)--that there is no better way (bunkers come to mind, of course, but you could also build an asteroid defense system and create measures to prevent nuclear war as well) to do so.

  • And that you don't need to see comprehensive settlement, that you're fine with whatever the minimum viable settlement size is.

I think it's hard to confidently argue all three of those, and even if you do I don't think you end up with the kind of settlement that we really have in mind.  I consider it to be something of a secondary benefit--A good thing that nevertheless cannot and should not justify settlement by itself.

2. The ability to self-replicate (indeed, to expand and improve) is a fundamental requirement for any prosperous settlement or society anywhere.  This absolutely holds, in the strongest sense, for Mars.  Even if we ignore the abstract requirements for settlements in general, Mars is so far away and so hard to get to that any rational cost-benefit analysis will suggest that the bulk of the items consumed on Mars must also be produced there. 

3. However no system in this universe is completely closed to outside inputs.  In traditional economics, the thing we're talking about here is called "autarky".  It hasn't existed in any advanced society on Earth, but Mars is pretty unique as far as the combination of high technology and high travel costs (On Earth, high technology has increasingly tended to reduce travel times and costs to levels where extensive international trade is economically desirable even far away from immediate borders; On Mars, high tech makes settlement possible even as trade is much less feasible).  The physical limit to self sufficiency is the requirement for an energy input. 

In the real world (and I have definitely said this before) practicality suggests you might try to trade for high value-low mass components.  Things that are hard to manufacture, will only be manufactured in low volumes, or have no mass at all (i.e. certain kinds of services that can be done about as well on Earth as on Mars)  This would imply a need for export goods and/or services, or ongoing financial support from Earth.

4. To the extent that you approach self-sufficient replication, you do so asymptotically.  For a given measure of closure, it will require more and more effort on the part of any settlement or society to get closer and closer to complete closure.  Any reasonable group of people concerned with their own welfare and survival will decide at a certain point that they have enough closure.  What this "enough" level is (If Earth is suddenly rendered useless for whatever reason, does the settlement fail or is there a small decline in the standard of living and temporary shortages in certain products?) is quite hard if not impossible to say in advance.

5. There are limits to what we can know and guess at as people sitting behind keyboards on Earth.  The range of possibilities for self-replication lies between "difficult but doable" and "virtually impossible", and anyone who claims to know better probably doesn't know very much at all.



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