Closed eco-systems

From: victoriatangoman [mailto:tango_dancer@...]

I've had my reservations as to the wisdom of the reduced atmosphere
position but have been unwilling to defend a position because of the
scarcity of experimental data on the complexity of the new
environment and most importantly, I'm really out of my depth in this
field.

You may well be right to have such reservations. There's a lot to be
considered, such as heat and sound conductivity, as well as the ecological
issues you raise.

But I would point out that O'Neill's atmosphere proposals were more
conservative than a couple which have been made since. Zubrin advocates an
atmosphere with 1/3 the pressure and 3 times the oxygen percentage, while
Savage talks about 1/5 pressure atmospheres of almost pure oxygen. My
thinking is that if the 1/2 pressure atmosphere is going to have problems,
then the others are going to get us into even bigger trouble.

I believe that even for Island 3, O'Neill's initial calculations assumed
sea-level pressure air, an assumption he later called "naive". Still, if
lower pressure/higher O2 percentage atmospheres do turn out to be a problem,
we can still build habitats as large as Island Three with sea-level pressure
air.

Regards,

Mike Combs

From:
victoriatangoman [mailto:tango_dancer@...]
I've had my reservations as to the wisdom of the reduced atmosphere
position but have been unwilling to defend a position because of the
scarcity of experimental data on the complexity of the new
environment and most importantly, I'm really out of my depth in this
field.
You may well be right to have such reservations. There's a lot to be considered, such as heat and sound conductivity, as well as the ecological issues you raise.

But I would point out that O'Neill's atmosphere proposals were more conservative than a couple which have been made since. Zubrin advocates an atmosphere with 1/3 the pressure and 3 times the oxygen percentage, while Savage talks about 1/5 pressure atmospheres of almost pure oxygen. My thinking is that if the 1/2 pressure atmosphere is going to have problems, then the others are going to get us into even bigger trouble.

I believe that even for Island 3, O'Neill's initial calculations assumed sea-level pressure air, an assumption he later called "naive". Still, if lower pressure/higher O2 percentage atmospheres do turn out to be a problem, we can still build habitats as large as Island Three with sea-level pressure air.
Regards,
Mike Combs