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RE: starship-design: Interstellar mission within fifty years


> > No, this is an engineering study. JPL has tested the reactions
> > and verified the energy output.
> >
> Actually maintaining a sustained fusion reaction with positive energy
> balance? It would be quite a media event, such an experiment!

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.

> But we are discussing needs of an interstellar flight,
> not a single ICAN spacecraft.

True, but we have to start somewhere. You will note however that the AIMSTAR
paper uses some of the results of the ICAN testing at JPL and includes a
rather startling observation. ICAN assumed that the antimatter would be
consumed each time by the reaction, actually, it was not. It took three or
four cycles before it had to be replenished. It is only a catalyst remember.

> The current containers can store only picograms or even less
> of antiprotons, have an astronomical mass ratio (container/antimatter),
> and can store the antiprotons only for few days
> (they slowly annihilate inside...).
> Scaling it up to tons of antimatter stored for tens of years
> without loss will need quite a breaktrough in storage methods
> and technology.

Slowly, annihilate? Not according to the paper I read. ICAN and AIMSTAR
don't need tons. An interstellar drive based on an outgrowth of AIMSTAR
would only need a few grams, I don't see a problem.

> > (they drove around the U.S. with the
> > storage container loaded with antimatter in the back, we're
> still here so I
> > guess it worked.)
> >
> That's news. As far as I know, they said that some time
> it will be possible...
> Did they already get proper permits to haul antimatter
> on U.S. highways? I doubt that.

Well, it isn't really all that dangerous, even if the Penning Trap had
failed, it would only have gotten a little hot, its not like it would have
exploded or anything. Since it isn't an explosive, poison or hazardous
waste, no permits are required.

> You say it has performance good enough to put it into
> a starship?

VASIMR? Heck no. Its strictly interplanetary. Unlike the ACMF proposals it
will never scale to interstellar. However, it uses several technologies
which are crucial to enhancing the performance of later generation of ACMF
or even true antimatter drives. 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.

> Seems to be a misunderstanding here.
> I agree about start & self reinforcing, I even said explicitly
> that prior experience is necessary. It was YOU who wrote
> that building permanent habitats in space before building a starship
> is "not necessarily" needed...

Nope, I said it wasn't necessary to build a manned habitat to mine
asteroids. Then promptly intimated that WE would prefer that they were
manned because we need the experience working in space precisely because it
was necessary in order to build a starship.

> Exactly. Almost.
> I questioned that we may discover "a habitable planet" from Earth.
> I am in no way against going to find out.

Oh I think given a few more years we will be able to tell from here whether
it has an Earthlike atmosphere or not - which doesn't necessarily mean that
it is "habitable". Which is why I said the only way to find out is to go.

> Yes and no. I think it will be easier to settle a planet
> (in the sense of building a permanent, self-sutained habitat
> for a significant number of people), that building equivalent
> artificial colony in space, at least in a foreseable future.

Well, I think most people, including the general public would agree with you
there. I am just saying that it makes more sense to settle the system's
asteroids, moons and other ore rich bodies first, but that is a whole
different argument.

> I see that I must add a proper disclaimer:
> ------------------------------------------
> I am not such a die-hard pessimist, as some of you seem to think.
> My point is that quite a lot of hard problems still remains unsolved
> and needs much work to solve. Hence I think that easy optimism that
> all is already essentially in place (as expressed in some posts lately)
> may be quite unreasonable, generating too much self-confidence
> where a call to arms seems more appropriate.

I agree.