How Earthlike?

I'm very familiar with the space settlement literature, have read all
the studies from the 70's, and have found some of the ideas recently
proposed on this list novel, interesting, and a few are even sort of
practical. Furthermore, it's a fact that some (not a majority) NEAs
have delta-v from LEO less than our Moon.

andy-nimmo wrote:

> Hi John,
>
> Much, if not most of this discussion is nothing but a rehash of work
> that was already done back in the 70s. For psychological reasons you
> will end up with an Island 3. Living in either a torus or a sphere
> would literally drive too many people bonkers to be practical. Also,
> your idea that most NEAs are easier to get to and return from than the
> Moon is totally different from what I have been told - in fact it's
> the exact opposite of what most of my scientific friends believe.
>
> Having said that, I am delighted to see this discussion going, as it
> clearly indicates some revival of interest in space settlement over
> the 80s and 90s during which it seemed to wain considerably.
>
> Best wishes, Andy.
>
> John Frazer wrote:
>
>> andy-nimmo wrote:
>> > How do you build tall buildings on the 6 - 10 metre thick inner
>> surface of a habitat? I would think O'Neill's preference for small
>> buildings was a simple matter of constructional capability.
>>
>> I don't know; A lot of O'Neill's (more accurately Davis's?) work
>> seemed to depict the idyllic setting.
>> Are we talking of skyscrapers? They may not have thought of these
>> because there's no need for single massive buildings.
>> For structural considerations, they would have to be planned into
>> the colony design: Counterbalanced, with extra tensioning cables in
>> the sub-floors or hull.
>> Anything which needed such concentration of subdivided yet close
>> proximity spaces would probably be in sub-decks under the habitat
>> floor, unless you really wanted big buildings for some reason.
>> Another possibility is the endcaps (If you're thinking of the
>> island 3, but we seem to have agreed to use a more inherently stable
>>
>> geometry).
>> For the Stanford Torus, a cluster of "City" at every other spoke
>> gives 3 cities, with the other spokes coming down in more rural
>> settings. Anything too big in a torus is part of the roof support
>> structure. (I think Heppenheimer's book specified that the spokes
>> would be the skyscrapers in the habitat) Also, anything too big has
>> to be balanced.*
>>
>> It all depends on the population density at the floor level. If
>> we're
>> packing them into an early habitat, then maybe the entire torus is
>> built up like an arcology, with only some relatively small open
>> volumes for relief. Later, after the space cadets can afford the
>> extravagance, it'll be like the image of the forested open torus, as
>>
>> was depicted in O'Neill's book.
>> The population density at 10,000 may be an average mean. A habitat
>> for an early company city (consider the Panama Canal Zone through
>> most of its history for an example of this), might hold 20,000 or
>> more. The later, independantly wealthy retirement village or
>> wildlife
>> refuge might only have 5,000 or less.
>>
>>
>> * For another view of an administration/colony services volume,
>> think
>> about this for a Bernal sphere; 2 or 3 hills in the open inner
>> habitat volume are hollow, with the admin center built into them.
>> Sunllight can be piped in from outside with fiber optics/ light
>> conduits, so it can have real sunlight at any time in any room
>> regardless of day/night cycles for the habitat. We may or may not
>> want to go high enough for radically diferent gravity at the top.
>> I can see all the traffic jams of ultralights & bicycles from all
>> the commuters coming to the hill city from thier homes in the plains
>>
>> suburbs.
>>
>>
>>
>>
>>
>>
>
Al Globus
aglobus@..., (650) 604-4404
http://www.nas.nasa.gov/~globus/home.html

The dinosaurs weren't spacefaring. We are. I don't think that's an
accident.
Maybe we are life's taxi to the stars.

I think we should:

1. Devote half of NASA's budget ($7 billion) to reaching NASA's 2020
goal of
reducing launch costs to Low-Earth-Orbit to $220/kg with a 0.01% failure
rate.
This should enable space tourism. The resulting orbital hotels will need
to
develop efficient orbital life support and other necessary technologies.

2. Build orbital space colonies. The materials in the largest asteroid
are
sufficient for orbital colonies with a combined surface area about 500
times
greater than Earth's. Eros alone could make over ten thousand space
colonies,
each with about about 10 square kilometers of 1g living area.

3. After a few generations of orbital living, people won't need their
colony
to be near Sol. Then small groups of colonies with populations in the
tens-of-thousands can set out on multi-decade journeys to nearby stars.

Except the launch goals, none of this is even a little bit official.