From: vince@offshore.ai (Vincent Cate)
Newsgroups: sci.space.tech
Subject: Re: Radiation shielding for hotel at GEO?
References: <9186edb5.0308081641.5036919e@posting.google.com> <36dabe8a.0308090619.b5cba5c@posting.google.com>
NNTP-Posting-Host: 209.88.68.230

len@tour2space.com (Len) wrote in message news:<36dabe8a.0308090619.b5cba5c@posting.google.com>...
> IMO, the real problem is shielding for the transport
> vehicle carrying people to GEO, L-5 or the moon.  
> [...] 
> For a lunar hotel, the people transport from Earth-to-
> moon and back might carry water shielding to the moon, 
> and lunar materials back.  Whether or not this could 
> yield reasonable economics remains to be seen.

With tethers you can make a shielded transport cycle between
GEO and Lunar orbit with all the delta-vee handled by tethers.
A GEO hotel makes a good staging area for combining the small
payloads tossed every 100 minutes by the LEO tether into a
few big tosses every 2 weeks when the Moon crosses the plane 
of the hotels equatorial orbit. A big hotel makes a great 
ballast for tossing a big transport.  The delta-vee going 
from GEO toward the moon is not very high, so it is not hard 
to have a tether strong enough for a big transport.
 
As long as a tether catches as much as it tosses, it takes
very little energy/thrust to operate it. If you are generally 
sending more stuff to the moon you will want to bring some 
rocks back just to balance the tether traffic. I think it 
is really fun that you can sort of lower rocks from the 
moon toward the Earth and use that energy to lift stuff 
up to the moon.

Going from the suborbital rocket to the GEO hotel is like 
4 hours (compared to like 4 days to go to the Moon).  If we 
could predict when there would not be any solar particle events 
for the next 4 hours then this transport would not need much 
shielding.  If it does need good shielding then we could have 
a shield that cycles between the GEO hotel and the LEO tether.  

My problem is just figuring out how long the galactic cosmic 
radiation will let me live on a GEO hotel before I have to 
move onto the Moon, where I can easily have 5 meters of 
shielding.  :-)

   -- Vince

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 Vincent Cate                           Space Tether Enthusiast 
 vince@offshore.ai                      http://spacetethers.com/
 Anguilla, East Caribbean               http://offshore.ai/vince
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

You have to take life as it happens, but you should try to make it
happen the way you want to take it.    - German Proverb