Spaceships and Solar Systems

A thread of 3 messages, 5 February 1990 to 7 February 1990, in the order they were sent.

#925 Spaceships and Solar Systems

Hi gang,

I wanted to thank everyone who responded to my questions about fusion
drives, etc. and, for those who are interested, pass on my general
conclusions.  I have drawn, in addition, on the work of Dean Ing,
Charles Sheffield, and Robert L. Forward for some of the technical
information; I am grateful to you people for filling in some of the
gaps they left unexplained.

I have ended up with a system that, for fusion drives, uses .5 g/sec
per ton of thrust at one gravity (i.e., acceleration of one ton of mass
at one gee).  This means that if a spacecraft is 30% fuel, it can thrust
at one gee for 600000 seconds, giving the spacecraft a terminal velocity
of 2% c, although what most ships do, since they want to be able to stop,
is to boost to about 2500 km./sec. and then coast until they need to
decelerate; about 20% of the fuel supply operates as reserves for mid-
course corrections and that kind of thing.  Matter-antimatter drives
can do about 12 times better.  This means that the best a fusion-driven
spacecraft could do, without being a multi-stage vehicle, is about 5% c
(terminal velocity; 2% c and maybe a little more if you want to be able
to stop at the end of the voyage).

What all this means is that it takes a few days to get to Mars, a bit more
than a week to get to Jupiter, and a few weeks to get to the outer planets.
If you coast for a year, you find yourself in the inner reaches of the
cometary halo.

Some people have been talking about solar system generating, etc.  One
thing I have always wondered about is why the Traveller system, especially
Megatraveller, has not assumed a space-industrialized society.  You do not
have to worry about whether or not there are Earth-like planets in a solar
system, or terraforming candidates, if you have either an asteroid belt or
gas giants with moons (and preferably both).  Instead, you built habitats
(even conservative estimates show that you could build microworlds that
could house a million people, and you have enough materials in almost every
solar system to build hundreds of thousands to millions of those habitats).

What I've ended up with are solar systems that have populations in the
hundreds of billions, living in hundreds of "archipeligos," each cluster
of habitats (usually hundreds or thousands in each one) centered around a
fair-sized airless body, like a big asteroid or the moon of a gas giant.
If you're interested in adventures that involve trade, politics, corporate
misbehavior, espionage, privateering, terrorism, and a whole range of
criminal activities, I recommend this kind of universe.  (I also
recommend Bruce Sterling's SCHIZMATRIX as source material...wonder when
Steve Jackson will get around to making a GURPs version  :)  )  My
experience running this kind of universe is that the possiblities are
pretty much limitless, even if you never travel beyond a single solar
system!

Anyway, take care, please feel free to respond to the subjects I've
brought up, and have fun.

   Mark

P.S. I would have liked to join the PBM game, it sounds interesting, but
I am simply too busy to do it this time around.  If another one is played,
I would be interested.


All opinions and material above is the responsibility of the originator.
Submissions: [email removed], or [email removed]
Administrator: [email removed] (James Perkins)
The TML is made possible by facilities provided by Tektronix, Inc.

#932 Re: Spaceships and Solar Systems

True, Traveller may be ignoring the possibilities of a completely space
based society in a system.

On the other hand, try to find a copy of "Outcasts of the Heaven Belt". This
novel deals with such a society 50+ years after a a war. Their tech level
is rapidly dropping due to loss of skills and resources during the war. And
they are getting pretty nasty, as factions try to keep *their* habitats
going.

Planets are only necessary if you need to be able to have survivors after
a major "oops!". The minimum tech level that will allow life on a habitable
planet is 0. The minimum for a space colony is higher than *our* current level!
Say at least 9. This has grave consequences.

All opinions and material above is the responsibility of the originator.
Submissions: [email removed], or [email removed]
Administrator: [email removed] (James Perkins)
The TML is made possible by facilities provided by Tektronix, Inc.

#945 Re: Spaceships and Solar Systems

[This came to [email removed], looks like it was
meant for [email removed].  Watch those automatic reply
headers! -- James]

Absolutely true about space habitats, but if you have a large enough
population base, the entire society is unlikely to crash, although there
may be technological breakdowns that cause individual habitats or even
archepelagos to die.  I have a feeling that once certain technologies
are available, and humanity has spread to a broad enough population base,
and a large enough number of locations, we will have passed some critical
point where the only thing that can wipe us out is several supernovas.
In addition, I assume in my gameworld an intergalactic community of
intelligent races; mankind has enough powerful allies at this point that
even if every one of the several thousand solar systems we inhabit were
attacked (an enterprise that would cripple the economy of almost any
civilization), we would still not be totally wiped out.  Those habitats
that survived would have to go into debt, in a big way, but there would
be parts and skilled labor available for those who needed it.



All opinions and material above is the responsibility of the originator.
Submissions: [email removed], or [email removed]
Administrator: [email removed] (James Perkins)
The TML is made possible by facilities provided by Tektronix, Inc.