Nomadic Interstellar travel

From: "John Frazer"
To:
Sent: Friday, July 27, 2001 9:50 PM
Subject: [spacesettlers] Nomadic Interstellar travel

[snikt]
> Note the energy source: each person is given (arbitrary) 1MW
> of power. This means that a colony of 500 needs about
> 30,000km radius mirrors (SWAG, I don't remember the article
> precisely). With this, you get your power from the brightest star in
> the sky, and it's not necessarily the closest.
[snikt]
> They use huge mirrors to catch starlight, instead of fancy fusion
> or antimatter (Impossible? Unknown.).

Well... A mirror 30 Mm in radius, even assuming a microscopic thickness of 1
micrometer, would have a volume of 2832 Km^3 - equivalent to that of an
asteroid of 17.5 Km in diameter. It is not, to say the least, an easy thing
to do. Even if we assume a nano-structured mirror 1 nanometer thick, we
still would need a 1.75 Km asteroid. Also, how to shape something that is
thin as a cell membrane but has the surface area of a giant planet, so that
it will focus starlight in an area a few kilometers across?

For those reasons, planet-scale mirrors sound less credible to me than
fusion reactors. I don't have much problem imagining a couple of mass
drivers tens of kilometers long colliding deuterium pellets inside a hollow
reaction chamber in the center and thus producing a (presumably)
energy-efficient fusion, but I have problems imagining something like the
mirrors described above.

So, I have a gut feeling that colonization of the Oort Cloud will be viable
only with nuclear fusion - which is a tricky thing to do in a room-sized
reactor on Earth, but does not seems to be particularly difficult to do with
big enough structures in space. And, even though for some reason artificial
controlled fusion is proven to be impossible, comet dwellers can always
filter their comets to get uranium and thorium (it would be a process akin
to mining the ocean, I guess - again, not an easy thing to do), and get
their energy from fission.

[snikt]
> The Zen way to the stars: Living the journey is important, not
> getting to the destination.
>

Yes! And, as you said, a natural consequence derived from space settlements.

[snikt]
Lucio Coelho