From: jsbell@acs.ucalgary.ca (Joshua Bell)
Subject: Colony ships, among other things...
Date: Sun, 05 Apr 1992 04:59:25 GMT
Organization: The University of Calgary, Alberta


Well, this is a little old, but I actually seem to be getting
news lately, so let me try to post this again. :)


In article <1992Mar22.192142.1@vaxb.acs.unt.edu>, someone'r'other writes:
>In article <1992Mar18.022534.6521@pimacc.pima.edu>, ppugliese@pimacc.pima.edu writes:
>> but it couldn't hold it. I prefer to believe that the north end of the
>> southern continent is actually above the equator. That way the planet
>wouldn't it have to be above the equator for the Dawn Sisters to have a
>'pern-stationary' orbit above Landing? I think it would, because, IMHO,
>geostationary sattilites (sp?) are above the earth's equator.
>rdc
>********************************Roger Cook*********************************
>roger@vaxb.acs.unt.edu OR roger@untvax.BITNET (UGH!) OR NTVAXA::ROGER

Hrm... someone just after Sorka hops out of the shuttle they make
a few references to the way the ships are hanging there.

They are NOT in Geosynch orbit... or at least they aren't some of
the times they are mentioned in the 'revised history' parts of
the Pern universe. :)

Geosynch is a horrible place to be. Its way, way too far out from
the planet to make repeated trips back and forth that energy
efficient (Even for Fussy Fusi. :). They mention Lagrangian
orbits, but Anne was her usual self about that, tossing in the
term w/o realizing quite what it meant, IMHO. Lagrangian orbits
are orbits relative to a moon of a planet (or a planet around a
star, for that matter)
                                   2 -------------\
                               . . o. .            >- Lagrangian Points
                            4 '    1    ' 5-------/
                           .              .
                          .  X     y       .
                          .        O Pern  .
                           ,              ,
                            .            .
                              ' .  3 . '  \_ Moon Orbit


Horkey dorkey: The .... line is the orbit of a moon. O is Pern, o
is one of the moons. 1-5 are the Lagrangian points (No, they are
probably in the wrong order... the important thing is that 1-3
line up with the moon and planet, and 4-5 are +/- 60 degrees of
the moon). Lagrangian points are 'stable' orbits in an
planet-moon system, with 1-3 semi-stable, and 4-5 dynamically
stable (if you drift, they pull you back). These are good for
space colonies (Eg, the L5 colony proposals), but not good for
ships w/ landers.

X is an estimated Geostationary point.... for a planet like Mars
this is actually outside one of its moon's orbits, and between
the other's. 'y' is where you want to be (In Trek Parlance,
'Standard Orbit, Captain' - the cool shots where the Enterprise
is hovering o-so-elegantly over the planet, or like you see in
shots from the Space Shuttle - Nice and low!)

Blue Planet! Blue Planet! (DC Gather inside joke. :)

Anyway, you can't mainitan an orbit of 'y' over one spot on the
planet without 'stationkeeping' - you need to FIGHT to stay
there. Aivas notes that the Buenos Ares and the Bahrain need to
be destroyed because they won't stay where they are for long. I
suspect Anne has them trapped in the magnetic fields of Pern
(which rotate with the planet) - she does tend to like
electromagnetic effects (see ATWOP). Plus, this lets the planet
itself munch some of the power requirements.

----------------------------------------------------------------------
Minor ATWOP Spoilers:

Next Question:

In Dragonsdawn the Yokohama is kept at 0.5g (except for the cargo
decks, at 0g). In ATWOP the Aivas mentions it was full gravity
except for the cargo decks at 0.5g or something (I'll look it up
later.)

Now, how the SHARDS do you get gravity in the ship? They don't
have Artificial Gravity, or Jaxom would have flipped them on.

Spinning? Lets take a look....

                                                  ____        
            __                   __            _-'    `-_      
           |  \|\               /__\          /  \ |  /  \     
           |HH||\-__       __--//__\\________|    \| /    |     
           |HH||-__ --|-|--  ||_/__\_========| ____/\____ |     
           |HH||- __--|-|--__|| \__/ ________|     \/     |     
           |HH||/-           --\\__//        |    /| \    |     
           |__/|/               \__/          \_ / |  \ _/
            ''                                  `-____-'

Now, the O part of the ]-<>-O ship is the 'cargo/living section'
with some cargo 'lashed between the midship vanes' (The <> part).

If the whole ship spun, you'd have one hell of a time
docking/undocking everything, and the central column of the ship
would be unusable (the difference in gravity head-feet would make
you dizzy.) Also, just spinning the sphere would put tremendous
tidal forces and shearing forces on the ship.

In any case, how were the decks arranged inside the ship? I
always assumed they were layered within the sphere, 'back to
front' so that during acceleration/anti-acceleration, you'd be
properly pressed to the floor. IE, on that diagram, like this:
                        gravity pulls you <-  ||||||||||||| 

But, alas, that doesn't provide diddly once you've stopped the
craft. 

Anyone have 1/2 a clue how it would work?

Joshua 
aka That J'shua person on PernMUSH

"I'm not a chauvanist pig but I play one on.... oh, wait, yes I am. :)"

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