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RE: starship-design: Interstellar mission within fifty years


> One million antiprotons are about (1/6.023*10^23)*10^6 grams of
> mass; twice that mass converted to energy is about 3*10^-4
> Joules.  Admittedly that turns out to be a fair amount of hard
> radiation (gamma rays plus pions and such) if you annihilate them
> all at once; perhaps you could give someone cancer or radiation
> poisoning if you direct them properly.  But you'd need many
> billions of antiprotons before you could blow anyone's hand off.
> However, it does seem as if antiproton-catalyzed fusion will
> require a fairly hefty supply of antiprotons.  Neither does it
> seem likely that you can generate enough antiprotons from the
> energy released by fusion to have a self-sustaining system.

Admittedly, it will take quite a bit more than what current Penning traps
hold to become "dangerous", you probably could dump them in your hand
without any significant effect. My intent was to illustrate by analogy that
the preceding statement was nonsense.

Antiproton catalyzed micro fusion is not self sustaining, it requires a
regular injection of fresh antiprotons every few cycles or so (which is
better than what we thought a year ago). It is, however, an over entropy
reaction, unless one considers the energy put into creating the antiprotons
in the first place, in which case it becomes the world's most expensive

However, I can easily believe that given fifty years, this sort of engine
could be using Lithium or Boron to produce much more thrust than the current
generation under development with the added advantage of being aneutronic.
Antimatter production will probably be a purely space-based industry
converting solar energy into antimatter for storage in large quantities
somewhere off-planet (talk about a terrorist target). This scenario dodges
the entire question of self-sustaining over entropy fusion reactors, which
although they would be nice, aren't necessary.

The problem is, even with a thousand fold increase in power provided by
Lithium, Boron, etc. (which is stretching it), this will only meet the
lowest level engine specification I am currently proposing to the group -
which means a trip duration too long for human explorers. It can be
considered an interstellar drive, just not one we can use to meet our goals.

>From what I can see of the plans for the next twenty five years in space,
commercial enterprise will be firmly ensconced throughout near Earth space
by that time. We will already have acquired much of the experience I was
talking about and which most members of this list seem to agree is
necessary. That leaves us the next twenty five years to bring to maturity
the technologies required to transition from interplanetary to interstellar.