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RE: starship-design: Interstellar mission within fifty years


> > ANY fusion explosion produces a positive energy balance.
> Perhaps you should
> > check out the site for AIMSTAR I posted last week, ALL of the
> data is there.
> >
> OK, I will.
> But did they test an actual micro-explosions in hardware?

The team working on the original ACMF concept using ion drivers actually
performed some hardware experiments to provide enough data to confirm the
theoretical predictions. The AIMSTAR concept however, although based on the
data provided by the ACMF experiments, has not been tested in hardware as
far as I am aware. The predicted performance was obtained by study of the
original ACMF experiments.

> Yes, and that supports my point - as it is not an antimatter engine,
> it means the true antimatter engines still need substantial technological
> (& scientific) breakthroughs.

But it is scalable, the current generation uses hydrogen, this technology
can be used with Lithium or Boron to achieve substantially higher ISPs.
Improvements in magnetic confinement technology may allow it to be boosted
even farther. As it stands right now, either of these drives turns the solar
system into our backyard and although not suitable for manned interstellar
travel, they could put a scientific package through Alpha Centauri in only a
few hundred years.

> > Slowly, annihilate? Not according to the paper I read.
> >
> But they slowly annihilate. This is the reason they can
> contain antiprotons only for several days. It is posted on the web.

Are we both talking about Penning traps?

> Only because of the very small amount of antimatter contained.
> Do you thing you may propel the starship with the amount
> of antimatter that when annihilated will make the engine
> "only a little hot"?

If you take common "flash powder" and put some in your hand and touch a
match to it, it will flash burn, you will not be seriously injured although
your hand may be scorched. If you take the same powder compress it into a
tight package and light it with a suitable spark, it will quite neatly blow
your hand off...

To say that a few picograms of antimatter are not dangerous in a rather
loose concentration in a Penning trap does not mean that they cannot be
quite deadly when properly utilized.

> > The fact that it is ready for flight
> > testing was the only thing that was significant. Someone wanted
> > an example of a real working space drive, I provided one.
> >
> But it is still not "real working".
> And it is at most interplanetary when it eventually will.
> Scaling it up to interstellar is certainly impossible.
> So we are back to square one, despite your example.

Here we go again, if I build a widget in my garage and test it in my garage,
but don't actually put it in a widget machine, you mean to tell me it isn't
real? Come on, get a life. VASIMR is fired almost daily, if you don't think
it is a real working engine, let them test it in you living room next time!
I understand a little skepticism now and then, there are certainly enough
perpetual motion machines and cold fusion devices running around, but to
call a functioning rocket engine sitting in a laboratory in a college in
Texas not real is really pushing it!

I never claimed VASIMR was interstellar capable, quite the opposite, I
specifically stated that it wasn't. It IS every bit as powerful as a fusion
engine, a lot easier to do, and working now. That is all I ever claimed it
was. This was all in response to your assertion that the technology was a
long way off. Maybe, maybe not. VASIMR is simply an example that the
technology may be closer than you think.

> OK, with that I agree. Then, why you added the <G> tag to
> that your sentence?

The grin was to emphasize the point that even though I disagreed with the
statement about automation, I (and we) would personally rather they were
manned because we have our own agenda, it was not meant to make you think I
was speaking tongue in cheek! I believe that a lot more automation will be
possible than we are allowing for, but I personally don't believe in sending
robot probes to the stars. The whole point is that WE want to go, not our
electronic henchmen.

> It would be very interesting to actually compare realistic
> costs and technology needs to build both kinds of habitats.
> You may have more ores handy in asteroids, but much larger
> demand for them and for high-technology machinery if you
> want to build the habitat on or near an asteroid
> instead of on a planet (with atmosphere, gravity,
> appropriate temperature & possibly oceans...).
> I still think the balance is towards a planet,
> at least with current technology.
> It may change when the space/asteroid habitats
> will be a common thing, with appropriate construction
> and maintenance technology evolved into something familiar
> and efficient (and possibly with gentic-engineered species
> of humans to live in this environment).

I don't know. This is another of those areas where we can't tell because we
haven't done it yet and therefore have no comparison. At a guess, I would
speculate that it will be a net wash - it will not be a great deal more
profitable nor a great deal more expensive for either case. Mostly because
in order for the space portion to become possible, the rules have to change
enough that it mandates that the costs will be equal and any technological
improvements that make this possible will probably have off-setting benefits
to life on Earth that we haven't even thought of yet, so again, the costs
balance out.