Re: starship-design: Interstellar mission within fifty years

[Zenon Kulpa <zkulpa@zmit1.ippt.gov.pl>]

> From: KellySt@aol.com
> 
> In a message dated 10/19/98 8:28:27 AM, zkulpa@zmit1.ippt.gov.pl wrote:
> 
> >> From: KellySt@aol.com
> >> 
> >> >> Big disagree. In space building a O'Niel is probably easier 
> >> >> then landing and building the infastructure for a similar 
> >> >> sized city. In space your not cut off from resources and
> >> >> free power, and transport and lift costs are about nil.
> >> >> 
> >> >Only if you assume that all resources should be transported 
> >> >to the planet base from space/asteroid mines. However, a planet 
> >> >suitable for settling by definition should have the necessary 
> >> >resources on the surface - including such hard-to-find in space 
> >> >resources like gravity, atmosphere (providing additionally 
> >> >radiation shielding), running (or subsurface) water,  
> >> >appropriate temperature, base-building materials...
> >> 
> >> Materials are harder to get on a planet then in space 
> >> (water, ore, air subcomponents) 
> >>
> >Possibly harder to find, but easier to exploit.
> 
> How? The ore is higher grade in space. Near nil transport and thermal power
> costs. No need to break open a montain to get to it. Little problem in
> forging and welding it together.
> 
But much less trouble and hence lower costs of building 
and maintaining habitats and working gear (space suits) 
for needed human personnel.


> >> spining for grav isn't hard.  
> >>
> >Still not yet tested practically .
> 
> >> Probably no real chance of
> >> finding a planet with 1 g, 
> >>
> >Say, 0.6 to 1.5 g will be equally good.
> 
> We have no way of knowing, but data suggests not.
> 
Hmm, what data? We have sufficient experimental data only
for 0g and 1g, and a little data for 1/6 g (due to Apollo...).
>From these data (and history of my body weight... ;-) 
I suggest that the range 0.6 to 1.5 will
be acceptable (pending evidence to the contrary).


> >> right temp range, and non toxic but breathable air anyway.
> >> 
> >I am not asking for as much as air being breathable.
> >Having a decent atmosfere has other advantages than breathing it:
> >solar & cosmic radiation protection, no need for pressure suits
> >(oxygen masks suffice - provided it is not toxic through
> >skin contact: HCN or CS2 or the like are certainly rather bad,
> >but methane, CO2, nitrogen, even little ammonia are bearable),
> >lower temperature variation. 
> 
> Ah ha. Your taking an encampment on a frozen methan or amonia world 
>
Who said frozen? I have said "right temperature range"...

> with possible toxic life
>
Assuming no life, or at most some sparse life, proven harmless
(e.g., due to completely different biology). 
Here we essentially agree.

> and high expense, 
>
??? My thesis is that it will be less expensive,
so you can't assume "high expense" as a given -
you must prove that it actually will be expensive.


> and unknown rad level, 
>
??? The first automatic probes landing on the surface
will tell us of the rad levels and many others necessary
parameters before we ever attempt any manned landing. 
And rad levels under the atmosphere (and especially 
on a planet with magnetic field - one more possible advantage 
of a planet-surface habitats) will be significantly lower 
than in space - which will make heavy 
radiation shielding and rad-safe suits unnecessary.


> instead of a O'Neil?!
> 
Yes, instead of. And even "more instead" of habitats on asteroids.
We know pretty well how to build habitats on planets
of the characteristics I have described, and how to move around 
on their surfaces; we have no experience with O'Neils or 
vacuum/low gee/high temp variation asteroid environments.
Hence untill for some reasons the technology will be
finally developed, actual experimental habitats build, 
and experience gathered, it will be much easier to build habitats 
on (some) planets. 
E.g., we know pretty well how, and have most of the technology needed,
to build permanent base on Mars. It is not true even for the Moon
(lack of essential resources, cosmic/solar rad levels, no atmosphere,
high temperature variation, etc.), not to speak of the asteroids.

-- Zenon