> First, it is not clear why a terraformed planet would be safer than a space
> habitat, as you are hinting. What are you thinking about? Meteoroid hits?

Well, this is where the vagueness of future technology comes into play,
but mechanical breakdown, either accidental or intentional, seems much
more catastrophic if you need it to breathe. Personally, I'd just feel a
lot safer in general if I'm in an environment that can sustain my life
without needing to be completely sealed off via plastic or metal from a
hostile external environment. Yes, I recognize that a big enough rock or
chemical reaction could destroy an entire planet's atmosphere, but the
scale of the destruction required for such a catastrophic event is a few
orders of magnitude greater than what's needed to destroy some sort of
biodome. Maybe I'm just old-fashioned?

>
> Second, I think that the advantage of the negligible gravity well in a space
> habitat more than compensates for the doubtful advantage of "safety" in
> terraformed planets. Human beings are used to populated areas were
> transportation is easier; that's why the vast majority of Earth's population
> live near the oceans or near navigable waterways, which are also the
> wealthiest regions - it does not matter that the regions close to the oceans
> are also prone to hurricanes, tsunamis, raise and fall of ocean level, etc.
> In terms of space transportation, space habitats would be equivalent to
> regions nearby the "cosmic ocean", while terraformed planets would be
> equivalent to the innermost portions of a continent...
>

Interesting analogy. I wonder if people remain clustered in cities now
because that's where they were first, then? Since it's not that difficult
to get from any one point in the world to anywhere else any more thanks to
airplanes. And I can tell you, flying out of Logan Airport in Boston is a
pain in the patooshki. And it's actually a lot cheaper to live in the
Midwest of the United States than either coast these days, so can cost
still be considered the primary factor? If this is the case, I wonder if
Lunar or Mars-based biodomes will be more or less popular than permanent
space-based habitats? And will it all come down to which became the
standard mode of settlement first?

> --Lucio
>

Cheers,
--Justin

First, it is not clear why a terraformed planet Personally, I'd just feel a
lot safer in general if I'm in an environment that can sustain my life
without needing to be completely sealed off via plastic or metal from a
hostile external environment.
>>>>>>>>>>.

Really ? Have you flown in pressurized aircraft ?

Lots of people do, and they seem quite happy with it.

> In a message dated Tue, 5 Jun 2001 4:21:29 PM Eastern Daylight Time, Justin jhouk@... writes:
>
> First, it is not clear why a terraformed planet Personally, I'd just feel a
> lot safer in general if I'm in an environment that can sustain my life
> without needing to be completely sealed off via plastic or metal from a
> hostile external environment.
> >>>>>>>>>>.
>
> Really ? Have you flown in pressurized aircraft ?
>
> Lots of people do, and they seem quite happy with it.
>

Do I do it? Yes. Do I feel safer in the aircraft than when my feet are
on the ground? Not even a little. If I were given the choice to spend
the next year of my life in an aircraft or on the ground, I'd probably
choose on the ground. ;-)

--Justin

>
> Do I do it? Yes. Do I feel safer in the aircraft than when my feet are
> on the ground? Not even a little. If I were given the choice to spend
> the next year of my life in an aircraft or on the ground, I'd probably
> choose on the ground. ;-)
>

The cost of containers is a lot cheaper than the cost of terraforming
and can be done a lot more quickly.

Terrafroming will not happen within my lifetime, or even for several
generations.

It is so long term and hypothetical I really do not see any point in
discussing it.

I am interested in practical projects to get us out there as quickly as
possible.

I would rather visit a container space colony today, or at least within
my lifetime, than dream about a terraform planet I will never see.

The general public has a good comfort zone for flying in pressurized
aircraft, so I really do not see container colonies as something people
will regard as unsafe. In fact, they will be safer than commercial
aircraft today for several reasons.

Great points, Charles. The messages in this list that I enjoy most are
those with near-term focus. Discussions of terraforming are not too
interesting to me, because I'll be in my grave long before such things
happen. Same comments for fusion drives and other far-out technologies
that are mentioned from time to time. Today's technologies are sufficient
to begin moving out into space.

And let me further your comments regarding the safety of space colonies
versus airplanes. Airplanes have to be light in order to fly. A space
colony located a few kilometers away from an NEA could have concrete walls
of arbitrary thickness --- quite a difference from an airplane. An
airplane has to endure takeoffs and landings, fly through rain, sleet and
snow. A space colony just has to endure radiation and an occasional
micrometeoroid, both of which can be countered with heavy shielding built
from local materials.

NASA just recently contacted a deep space probe launched in 1965 that is
still operating; once we get out of LEO, the space environment is
actually fairly benign.

Ron Menich

Charles
very small ecosystems
06/06/01
09:10 AM
Please
respond to
ssi_list

>
> Do I do it? Yes. Do I feel safer in the aircraft than when my feet are
> on the ground? Not even a little. If I were given the choice to spend
> the next year of my life in an aircraft or on the ground, I'd probably
> choose on the ground. ;-)
>

The cost of containers is a lot cheaper than the cost of terraforming
and can be done a lot more quickly.

Terrafroming will not happen within my lifetime, or even for several
generations.

It is so long term and hypothetical I really do not see any point in
discussing it.

I am interested in practical projects to get us out there as quickly as
possible.

I would rather visit a container space colony today, or at least within
my lifetime, than dream about a terraform planet I will never see.

The general public has a good comfort zone for flying in pressurized
aircraft, so I really do not see container colonies as something people
will regard as unsafe. In fact, they will be safer than commercial
aircraft today for several reasons.

Ron,

Thanks for those remarks.

Regarding the safety of air travel, by coincidence I ran across and
interesting web site the toehr day which list some hazard of air travel,
interestingly those hazards would not apply to space colonies, making
them safer by comparison.

http://expat.ft.com/ft/gx.cgi/ftc?pagename=View&c=Article&cid=FT3P9PIZTEC&live=true&tagid=FTDP4AZ4QDC§ion=Travel

And even that site neglects to mention the radiation hazard.

Specificially:-

Poor quality of air conditioning is common, bacteria thrive in aircraft
air conditioning systems, transmission of airborne infections between
passengers is common.

Bloot clots and thrombosis (especially in the legs) due to sitting in
cramped conditions for long periods of time.

Indigestion problems due to expanding gases in the digestive tract

Dehydration due to the low pressure.

Elevated radiaiton levels due to increased exposure to cosmic rays at
high altitude.

Reference:-

Radiation Protection Training Course For Radiation Producing Devices
RADIATION PROTECTION TRAINING MANUAL & STUDY GUIDE FOR RADIATION
PRODUCING DEVICES. Jump to the Table of Contents. MAY 1994. LESSON PLAN
OUTLINE....
URL: http://www.inform.umd.edu/CampusInfo/Dep...rpd/device.html

Comparison of Calculated Cosmic-Ray
Doses to a Person Flying in Subsonic and Supersonic Aircraft
Average Solar Conditions

Subsonic Flight Supersonic Flight

at 11 km at 19 km

Dose

per per

Flight round Flight round

duration trip duration trip

Route (hr) (mrad) (hr) (mrad)

Los Angles-Paris 11.1 4.0 3.8 3.7

Chicago-Paris 8.3 3.6 2.8 2.6

New York-Paris 7.4 3.1 2.6 2.4

New York-London 7.0 2.9 2.4 2.2

Los Angles-New York 5.2 1.9 1.9 1.3

Sydney-Acapulco 17.4 4.4 6.2 2.1

Source: UNSCEAR 1977 Report

The table below shows the doses received by astronauts on various space
missions. The largest part of the dose was received when the spacecraft
passed through the earth's radiation belts. The belts contain protons,
electrons, and alpha particles trapped by the earth's magnetic fields.

Absorbed Dose in Chests of Astronauts on Space Missions

Mission or Launch Date Duration of Type of Orbit Dose

Mission Series (Yr-Mo-Dy) Mission (Hr) (mrad)

Apollo VII 68-08-11 260 Earth Orbital 157

Apollo VIII 68-12-21 147 Circumlunar 150

Apollo IX 69-02-03 241 Earth Orbital 196

Apollo X 69-05-18 192 Circumlunar 480

Vostok 18-6 Earth Orbital 2-80

Voskhad 1,2 Earth Orbital 30,70

Soyuz 3-9 Earth Orbital 62-234

Source: UNSCEAR 1977 Report
Individuals living around coal-fired power

Subj: Re: [ssi_list] Planetside vs. space-based WAS Maintaining very
small ecosystems
Date: 06/06/2001 6:37:39 AM Pacific Daylight Time
ssi_list@...

And let me further your comments regarding the safety of space colonies
versus airplanes. Airplanes have to be light in order to fly. A space
colony located a few kilometers away from an NEA could have concrete
walls
of arbitrary thickness --- quite a difference from an airplane. An
airplane has to endure takeoffs and landings, fly through rain, sleet
and
snow. A space colony just has to endure radiation and an occasional
micrometeoroid, both of which can be countered with heavy shielding
built
from local materials.

ecosystems

[snikt]
> Well, this is where the vagueness of future technology comes into play,
> but mechanical breakdown, either accidental or intentional, seems much
> more catastrophic if you need it to breathe. Personally, I'd just feel a
> lot safer in general if I'm in an environment that can sustain my life
> without needing to be completely sealed off via plastic or metal from a
> hostile external environment. Yes, I recognize that a big enough rock or
> chemical reaction could destroy an entire planet's atmosphere, but the
> scale of the destruction required for such a catastrophic event is a few
> orders of magnitude greater than what's needed to destroy some sort of
> biodome. Maybe I'm just old-fashioned?
>

I myself have felt that way sometimes when imagining living off-Earth. But
that is just an emotional, instinctive reaction; perhaps the result of so
many sci-fi movies showing depressurization and people blowing out in
space...

However, when you do the math, you can demonstrate, for example, that the
probability of getting killed by an asteroid is the same of dying in a plane
crash. How that is possible? Asteroid hits are extremely rare, *but* they
have the potential to kill *billions* of people.

As for mechanical breakdown in a habitat... Punctures, depressurization,
that sort of thing... Considering natural ones, the only possibility that
comes to my mind is meteoroid hit, and the probability of a meteoroid big
enough to puncture a radiation shield ten meters thick is *very* low. And,
even if that happens, the atmosphere of the habitat would not be lost
instantly, killing everyone. In fact, depending on the size of the hole and
the atmospheric volume of the habitat, it could take weeks for people start
to getting dizzy due to low pressure - more than enough time to repair the
habitat.

Breakdowns of artificial origin maybe more probable. Mad terrorists willing
to blow a hole in the habitat, or war. However, even though that happens,
causing the loss of a great part of the population of the habitat, that loss
would be comparable to that suffered by a city bombarded from the air or
something; in other words, catastrophes affecting a habitat are of urban
scale, and not of planetary scale. A planetary-scale population would occupy
thousands of habitats and, considering this huge number of habitats and the
exceedingly bad luck needed to destroy all of them, it seems that this
population would be safer scattered through all those myriads habitats than
concentrated in a planetary surface. In fact, if we have a space-faring
civilization, planetary surfaces are not that safe from artificial
breakdowns, either: anyone could hit a planet with an asteroid...

[snikt]
> Interesting analogy. I wonder if people remain clustered in cities now
> because that's where they were first, then? Since it's not that difficult
> to get from any one point in the world to anywhere else any more thanks to
> airplanes. And I can tell you, flying out of Logan Airport in Boston is a
> pain in the patooshki. And it's actually a lot cheaper to live in the
> Midwest of the United States than either coast these days, so can cost
> still be considered the primary factor? If this is the case, I wonder if
> Lunar or Mars-based biodomes will be more or less popular than permanent
> space-based habitats? And will it all come down to which became the
> standard mode of settlement first?
>

Your hypothesis about most people still living nearby oceans and navigable
waterways being an inertial phenomenon is interesting and worth
investigation, certainly, but personally I still think that it does not fit
well the economic flux. Aircraft are economically viable for transportation
of people and goods that are light and extremely valuable (e.g.,
electronics). However, when your goods have to be transported by the
thousands of tons, then you *have* to use ships. I think that you will never
see oil, grains, ores and other things being air transported. So, there is
still an influence - and a powerful one - keeping the bulk of economic
activity - and therefore people - close to the oceans.

You could have *real* space*ships* - cargo ships able to hold hundreds of
thousands of tons of payload, or liners transporting thousands of
passengers - going from a space habitat to the other. On the other hand,
unless antigravity is invented, or huge space elevators are constructed, you
could not do the same thing depart from Earth surface. (Well, actually
perhaps you *could* do that - using nukes and destroying everything in a
radius of many kilometers. ;-)

[snikt]
> Cheers,

Cheers,

> --Justin
[snikt]

--Lucio