Re: [GZG] Space Terrain

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http://lists.csua.berkeley.edu/mailman/listinfo/gzg-lOn Fri, May 8, 2009
at 1:21 PM, Samuel Penn <sam@glendale.org.uk> wrote:

> On Friday 08 May 2009 16:00:45 Tom B wrote:
> > Okay, let's give this its own thread.
> >
> > As to Asteroids: I know the real ones are thin. However, for all
that, at
> > pretty much every Con I attend, there's a game with large, dangerous
> > asteroids. So my reference in the prior thread to 'asteroid racers'
was
> > from popular usage, rather than realistic space simulation. You
could
> > substitute 'racers who race around buoys and such' (there was a
stargate
> > SG-1 episode in the late seasons that focused around a spaceship
race
> that
> > included a close run around the sun and navigating a field of armed
> > range-capable mines).
> >
> > So, asteroids should probably really be: Not present on the game
table in
> > numbers or a small hull scrubbbing effect that persists throughout
the
> > game.
>

Or, as per my earlier post, toss one or two rocks onto the table and
call it
good. You could justify two as being in orbit around each other. But
then
they'd have to be fairly close if your MU scale is 1K km.

But that would be for a mature solar system. You might find more rocks
to
contend with in a very early developing solar system.

>
> >
> > Nebula: Indy brings them up, but my understanding was they were not
very
> > dense either - not much real risk or damage unlike how they got
portrayed
> > in Wrath of Khan. Aren't they pretty diffuse in real life?
>
> Very diffuse. What you normally see in Hubble/Spitzer images are
> composites of different wavelengths portrayed as false colour.
> Keep in mind, the same images often show stars in the middle of
> the nebulua - they'd be 100's of lightyears inside the gas clouds,
> and yet you can still see them.
>
> I've seen it mentioned that most nebulae would actually be invisible
> to the naked eye when up close. I don't know how true this is, and
> probably depends on the amount of sunlight.
>

Yeah, for your general nebula, pretty diffuse. But in star-forming
nebulae,
you will have localized regions of significant size where the matter has
been coalescing into stars and smaller objects to orbit said stars.
Those
*might* give you terrain to pay attention to.

>
> > Rings: Indy mentioned rings. What's a realistic estimation of ring
> > densities? How often do you see asteroids big enough to feature as
an FT
> > obstacle in a ring system? What sort of on-map separation would be
at all
> > close to reality?
>
> I believe they're very small particles, but as I said in my other
> email, I've never seen good images. They might count as a 'wall'
> that blocks/limits sensors.
>

I've been poking around trying to learn more about the composition of
Saturn's rings. They are thinner than I remembered from reading years
back,
but fairly wide (excellent for 2-D stuff, not so good for 3-D). Saturn's
rings span from the inner D ring approximately 6,700 kilometers from
Saturn's cloud tops to the fringes of the E ring, 480,000 kilometers
out.
Most of the rings are only a few tens of meters(!) thick with a total
mass
equivalent to a medium sized moon. The rings themselves are made out of
particles ranging from microscopic dust to barnyard sized boulders with
the
occasional few kilometer-sized object as well. Near-infrared
observations
from Earth have shown that the rings are composed mostly of ice crystals
with some impurities (i.e., rocky/dusty stuff).

>
> > Pulsar: In SFB, a pulsar used to emanate damaging waves your shields
> helped
> > thin out. Is this at all reasonable? Could a reasonable bit of space
> > terrain be done with some mechanic like this?
>
> Pulsar's often rotate with periods measured in seconds (or less), so
> any arc they sweep out will cover the entire table many times each
> turn.
>

Yes, pulsar periods are often measured in milliseconds. I think the
slowest
spinning pulsar rotates every 8 or 9 seconds. Most are at the sub-second
level. And their beams of EM radiation are very very narrow. So narrow
you
could easily move just a bit up/down from the plane it transcribes and
not
be wholly bothered by it.

If you want to get an idea of how fast pulsars spin, check out this page
of
pulsar sounds:
http://www.jb.man.ac.uk/~pulsar/Education/Sounds/sounds.html

>
>
> > Gas giant atmospheres: Are these viable? How deep? What sort of
impact
> > would flying through one or trying to hide in one have? They used to
> > feature a lot in Traveller for fuel skimming and ambushes. How
reasonable
> > is any of that?
>
> If you look at my chart, at the surface of Jupiter, you're being
> pulled 20" into the planet every turn. Saturn is a more sedate
9"/turn.
> Either way, if you're hitting the atmosphere at orbital velocities
> it's probably going to hurt.
>
> >From what I've heard, the visibility in some layers of Jupiter's
> atmosphere is clear out to 1000s of km. You may be getting close
> to how nebulae are portrayed in SF.
>

> B5 had at least one episode with combat inside Jupiter's atmosphere.
>

I would model Jupiter's atmosphere similar to clouds on Earth. After
all,
that's what they are. ;-)  And no, they aren't diffuse enough to
resemble
nebulae. Nebulae are diffuse because the atoms/molecules composing them
are
spread out over thousand or millions of km (or more). Jupiter's
atmosphere
doesn't enjoy that kind of spatial distribution. ;-)

>
> Not sure what a cometary tail would be like.

Probably something a bit more diffuse than Saturn's rings, made of sand
or
ice crystals.  And not likely to have multi-km sized objects in it.

Mk