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Message no. 1
From: Guido Hölker <guido@******.COM>
Subject: Space Travel
Date: Thu, 19 Dec 1996 16:27:23 +0100
I would consider space travel by sucking gas out of the space more than
unlikely.
The bigger the mass of the ship is the more gas you need and you need a big
ship (or at least a big sail or whatever) to get as much gas as possible.
And because mass goes with size for the power of three for the ship or
squared for a "sail", you come to a very quick end here
(a very good bok to this is "The Physics of Star Trek" (I forgot the author
but could have a look): This book has a decent look to things like
space-travel or beaming not only in Star Trek terms but in general. And it's
quite easy prooven there why this concept wouldn't work).
Even if so: 2 percent of the speed of light still means 350 years to the
next sun..
Which leaves super-light-speed-travel which means "wormwholes"of any kind
(or call it hyperspace or whatever.)
Unfortnaltely the nature of this stuff as far as anyone can tell not only
has the possibility of time travel as well, but every "hyperspacejump" or
flying through a wormhole has a time travel build in by nature, an
unpredictable one, of course..
OK: A moon station makes sense for deeper space travel, but only at a first
glance: If you can travel to the moon on a regular base, you can certainly
travel to the orbit quite easy, so it doesn't make a sense not to park a
ship in the orbit and land with a shuttle only.
But the orbital stuff sounds good, I will go and read the "corporate
shadowfiles"...

Thanks
Guido
Message no. 2
From: David Thompson <david.s.thompson@****.EDU>
Subject: Re: Space Travel
Date: Thu, 19 Dec 1996 13:30:47 -0500
About space travel -- what about the solar sail idea that works off the
momentum imparted by photons striking the surface of the sail. If I
remember correctly, it works theoretically, acceleration is really slow, but
top speed is way up there.

Whatever, just something I remember reading about.

--Dave
Message no. 3
From: Autumn / Shatterglass <laughingcrow@****.COM>
Subject: Re: Space Travel
Date: Sun, 15 Dec 1996 01:48:32 PST
Dave...

The trouble with solar sails isn't the top speed the ship can reach, or
even the amount of sail needed to propell it... The problem is
space-junk. Just like a sail down here on Earth, a solar sail of any
solid material would be torn by the impact of such pieces of stellar
refuse, and a torn sail tends to rip itself into even worse shape very,
very quickly. Out between the planets that could be a problem. It's not
like you can swim back to shore.

Soooo... You either have to have a sail that isn't vulnerable to
space-junk, or you have to have something that can KEEP the junk from
getting close to your yardage (which would be more like "milage" on one
of these ships, realisticly...) And remember... NOTHING can get past
this system, or you're in deep kim-chee, because even tiny bits of
debris can make a hole...

--Autumn
Message no. 4
From: Guido Hölker <guido@******.COM>
Subject: Re: Space Travel
Date: Thu, 19 Dec 1996 21:53:37 +0100
At 13:30 19.12.1996 -0500, you wrote:
>About space travel -- what about the solar sail idea that works off the
>momentum imparted by photons striking the surface of the sail. If I
>remember correctly, it works theoretically, acceleration is really slow, but
>top speed is way up there.


True: Theoretically it would work. But for this you need any sun nearby;
that measn that the frarer you are, the slower you go. And in certai
distances you would not accelerate anymore, because the "void" isn't a void
so it slows you down a bit.
Besides that: You would need sails with thousands of square miles and the
chance an meteor hits them isn't too small. So this is a very fascinating
(and old) idea in SF literature, but nothing pratical.
Oh, I forgot that maneuverability isn't too godd, too..
Message no. 5
From: David Thompson <david.s.thompson@****.EDU>
Subject: Re: Space Travel
Date: Thu, 19 Dec 1996 16:27:11 -0500
NOTHING can get past
>this system, or you're in deep kim-chee, because even tiny bits of
>debris can make a hole...
>
I knew there was a catch, thanks for reminding me...

--DT
Message no. 6
From: Tim Cooper <tpcooper@***.CSUPOMONA.EDU>
Subject: Re: Space Travel
Date: Fri, 20 Dec 1996 00:35:39 -0800
On Thu, 19 Dec 1996, David Thompson wrote:

> About space travel -- what about the solar sail idea that works off the
> momentum imparted by photons striking the surface of the sail. If I
> remember correctly, it works theoretically, acceleration is really slow, but
> top speed is way up there.
>
> Whatever, just something I remember reading about.
>
> --Dave
>

Check out a piece of good sci-fi called "Roche World". A ship is sent ot
a distant solar system utilizing a solar sail propelled by about 6
sky-scraper sized lazers orbiting Mars. ('Course it took quite a while to
get there and they used some "anti-aging" drugs for the time spent in
transit...) But the stuff on the solar sails was pretty good.

~Tim
Message no. 7
From: Mark Steedman <M.J.Steedman@***.RGU.AC.UK>
Subject: Re: Space Travel
Date: Fri, 20 Dec 1996 11:47:57 GMT
Guido Hoelker writes

folks seem to be noting problems with a couple of the mentioned real
world methods of space travel so more comments.

> I would consider space travel by sucking gas out of the space more than
> unlikely.
> The bigger the mass of the ship is the more gas you need and you need a big
> ship (or at least a big sail or whatever) to get as much gas as possible.
> And because mass goes with size for the power of three for the ship or
> squared for a "sail", you come to a very quick end here

The 'interstellar ramjet/scoop' based idea i mentioned would use a
magnetic field to scoop material out the the dust between the stars.
Deep space is a nasty place and a lot of the medium is ionised so
could be collected like this and fed to a fusion reactor, ok you need
full hydrogen fusion (not the Heavy hydrogen we are working on now
(expected 50 years development yet) so we are taking centries off but)
This has the advantage that you don't have to have huge physical
scoops. And it gains enough energy because fusion if incredibly
efficient, the sun will burn on this source for about 10,000 million
years, i cannot remeber exactly but it would last about 100 years if
made of coal!

Solar sailing would work, but the thrust is very low and folks are
correct in saying metorites would be a problem.

> (a very good bok to this is "The Physics of Star Trek" (I forgot the author
> but could have a look): This book has a decent look to things like
> space-travel or beaming not only in Star Trek terms but in general. And it's
> quite easy prooven there why this concept wouldn't work).
Oh believed, but the Trek technical manual is still a good read, to
see how they claim it works, just a pity the show is so hopelessly
inconsistent.

> Even if so: 2 percent of the speed of light still means 350 years to the
> next sun..
No the scoop requires about 2% light speed for self sustaining, above
that scooping dust keeps the crew alive and gives thrust! so if you
can scoop enough fuel to get to 2% you have acceleration all the way
to revalistic speed and as the 'volume scooped for unit time' goes up
with speed and aging slows near light speed its not at all bad. Even
at 1/10th g you get to the nearby stars in a human lifetime. Managed
1g and you get to light speed in a year, thanks relativity and time
dilation anyplace in the universe in under about 70 years!

> Which leaves super-light-speed-travel which means "wormwholes"of any kind
> (or call it hyperspace or whatever.)
The latest stuff to make TV on this casts serious problems with
actually using wormholes, you colapse the wormhole in the process.

> Unfortnaltely the nature of this stuff as far as anyone can tell not only
> has the possibility of time travel as well, but every "hyperspacejump" or
> flying through a wormhole has a time travel build in by nature, an
> unpredictable one, of course..
> OK: A moon station makes sense for deeper space travel, but only at a first
> glance: If you can travel to the moon on a regular base, you can certainly
> travel to the orbit quite easy, so it doesn't make a sense not to park a
> ship in the orbit and land with a shuttle only.
exactly, but how many time have the good folks on star trek forgotten
the when the trnsporter break down they get a shuttlecraft!, and on
DS9 if the Cardassian computer system won't let you use the station
transporters, walk to runabout and use a Federation one! (that aired
recently on the BBC)

The use i sugested for the moonbase is mining material for orbiting
colonies, it being a lot easier to lift material off the moon than
the earth.

> But the orbital stuff sounds good, I will go and read the "corporate
> shadowfiles"...
>
> Thanks
> Guido
>

Mark
Message no. 8
From: Mark Steedman <M.J.Steedman@***.RGU.AC.UK>
Subject: Re: Space Travel
Date: Fri, 20 Dec 1996 14:09:58 GMT
Guido Hoelker writes

> Agreed, but hydrogen isn't ionised (if it where, you would only have
> elemental pieces and nothing to fusion with.
>
Ionised hydrogen becomes lone protons, H+
you can fusion these to give Helium nuclei, the electrons don't
matter at the sort of temperatures at which fusion occurs you cannot
have atoms only ions, the electrons have so much energy they long
since escaped limited orbits about atomic nucli. Everything become
ions before 10,000 celcuis i thing, hydrogen fusion needs 100milliom
odd degrees, which is why they are having so much trouble with J.E.T.

> >> Even if so: 2 percent of the speed of light still means 350 years to the
> >> next sun..
> >with speed and aging slows near light speed its not at all bad. Even
> >at 1/10th g you get to the nearby stars in a human lifetime. Managed
> >1g and you get to light speed in a year, thanks relativity and time
> >dilation anyplace in the universe in under about 70 years!
> Nope: According to relativistics you will never get to the speed of light.
> You won't even get close to it because the mass is raising with speed in a
> square-relationship and acceleration goes with mass in a square-relationship.
>
From what i've read at 1g continuous acceleration you appraoch light
speed in a year. I haven't bothered to find the equations and do the
maths myself. But have read book were its about 1/2 ly in 1 year, 10
in 2, 100 in 3, etc. You never make it to lightspeed of course but
relatavistic effecs are fairly negligable until you exceed .9C so you
get close enough. And as acceleration falls off time dilation
increases. What i did forget to say is these times are all 'ships
time' you never exceed light speed so travelling 10,000ly like this
will take 10,000 and a few years for the people back home, with a 2g
drive you might live to get there and back but it will be 21996
before you get back at least!

> >
> >The use i sugested for the moonbase is mining material for orbiting
> >colonies, it being a lot easier to lift material off the moon than
> >the earth.
> >
>
> Makes sense.
> And as we are already on this topic: does anyone has any experiences with an
> orbital Shadworun? (OI would love to cut down mages a bit from time to time..)
>
Magic and space are basically imcompatible. i can say more but big
time spoilers if i'm vaugely close and i probably am.
to busy right now.

Mark

Further Reading

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