Re: [gundam] Civilian Space Travel


Paul Fields (johnny_raiden@hotmail.com)
Wed, 31 Mar 1999 14:46:51 -0500


Hey don't kill off O'neill yet, since when did O'neill ever have people
living in the same
dirty debris ridden orbit as sattelites. Keep them out to Lunar orbit, and
the debris is
much less dangerous, especially if you plant your colonies behinng the moon
in orbit,
you use it as a debris snowplow to clear off any and your solar panels can
be huge, but
solar panel farms that send power to earth would need to be close for them
to work, and
O'neill probably hadn't planned on the commercialization of space to the
degree that it
exists today. If we had solar farms beaming energy down, they could probably
move
sattelites commo equipment to them, and clear up all unnecessary sattelites
by
consolidating their functions to the solar arrays. This would also save
trips to space,
workers who lived on the platforms could maintian the sattleites
electronics, and therefore
provide another savings. And no need would exist for thermalisotope style
power sources
to sit in orbit providing potentially lethal space junk if it ever crashed
into the earth.

Paul

>Matt Hanyok writes,
>
>>What about nuclear engines? I know people made a big fuss about a rocket
that
>>was launched a year or so back because it had a nuclear power source...
>>couldn't some kind of reactor work, or do I just have a misunderstanding
of
>>the way those things work?
>
> Yep, you'll get much further with a nuclear rocket engine; in a nutshell,
>these give you a higher exhaust velocity and hence greater "fuel
>efficiency." Better engines enable more aggressive flight patterns, which
>is why we presume that in emergencies Gundam warships might be able to get
>about the Earth sphere faster than the propellant-conserving spacecraft of
>today.
>
>
>Lim Jyue writes,
>
>
>> I'm not qualified to say much, but a nuclear REACTOR can only
>>provide power, not thrust.. current tech require a propellant, using
>>action-reaction to push the vehicle forward, but nuclear reactors generate
>>power by heating water/medium (as far as I know..=) to drive a turbine.
>
> But by the same token, the heated water (or whatever) can simply be
>sprayed out of the back end of the spacecraft to create a working rocket.
>This is the technique used in Gundam, and it's significantly more efficient
>than chemical rockets.
>
> When modern-day researchers talk about nuclear rockets, they typically
>mean "leaky reactor" designs where the plasma within the reactor is allowed
>to spray out though the back of the ship. For obvious reasons, this can
>only give you a pretty small amount of thrust, but the fuel efficiency is
>much higher dues to the plasma's high temperature (and hence high exhaust
>velocity).
>
> You can combine both approaches by mixing in water or some other bulk
>medium with the escaping plasma, trading off raw thrust versus fuel
>efficiency. In this sense, Gundam's non-leaky designs are at the extreme
>end of the scale, giving plenty of thrust but only modest gains in
>efficiency.
>
>
>>But there was this idea to detonate _nukes_ to propel a spacecraft...
>
> Yep, and this "nuclear pulse propulsion" is used in Gundam as well. In
>essence, you spit teeny fusion fuel pellets out of the back of the vessel,
>then use lasers to crush the pellets and trigger a brief fusion reaction.
>Conventionally, a metal "pusher plate" protects the ship and directs the
>blast backwards, but since Gundam's helium-3 fusion yields no neutral
>particles, you should be able to do most of this with magnetic fields.
>
> When you perform this operation a couple of hundred times a second, you
>get a continuous and highly efficient source of thrust. In Gundam, the
>system is used to move asteroids, Jupiter energy fleet vessels, and other
>large, slow-moving objects for which rapid acceleration is less important
>than fuel efficiency.
>
>
>>Anyway, the hoo-haa about the spacecraft you mention was because pple
>>were afraid a leak will contaminate the atmosphere.. not an unwarranted
>>fear, but still..
>
> Actually, I saw a news item the other day about Russian scientists who
>warn that chemical rocket engines are destroying the ozone layer (what with
>all these satellite launches), so space travel may be ecologically unsound
>any way you look at it.
>
> In other downer space news, a recent Sunday paper feature described local
>researchers who plan to beam energy _up_ to satellites - apparently, solar
>panel arrays are too fragile and vulnerable to damage from orbiting junk.
>If this is really the wave of the future, it's the death knell to Gerard
>O'Neill's dream, in which orbiting satellites would beam cheap solar power
>down to an energy-starved Earth, rather than vice versa...
>
> By the way, these researchers plan to use lasers rather than microwaves
>for energy transmission. The idea is to set up a huge Solar System-style
>grid on the ground, and focus the transmission on the satellite; in
>between, the beam would be too diffused to hurt anyone. This mechanism too
>is the opposite of O'Neill's, which had a small microwave transmitter on
>the satellite and a huge receiving array on the ground.
>
>
>-- Mark
>
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>Mark Simmons <mailto:scorpio@best.com>
>MacAddict: the magazine! <http://www.macaddict.com/>
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