Von Neumann machines. The key to space and much else.

I agree and disagree with what you say. I definitely think it is
challenging but not impossible. I agree too that the key is the
production of energy (solar panels).

I do feel that to produce solar panels, or anything else, in large
numbers the loop needs to be closed and a full VN machine will be
required.

As far as getting a variety of chemicals is concerned I do not rule out
bacteria and genetic engineering. Indeed there is already precedent in
that our mammalian cells contain cycloplasm which is in itelf a foreign
organism.

Ian Parker wrote:
Is it possible to make such a thing? In this reference NASA analyzes
the idea.
http://www.zyvex.com/nanotech/selfRepNASA.html
As you can see a considerable amount of work has been done on the
topic. NASA has in fact gone so far as to produce details of the number
of separate parts that would be required. The latest paper I can access
is 1990. After that the paper chase seems to grow cold.


COMMENT:

Von Neumann machines go back as an idea to Von Neumann in the mid
1950's, in a book he never got around to finishing before he died of
cancer, and which was published postumously.

The first person I'm aware of to take the concept seriously for
technical applications was atom bomb engineer Theodor B. Taylor, who
proposed seeding the moon with (large) von Neumann machines as part of
a space project, in 1977. Taylor noted somewhere along the way that von
Neumann machines could be programmed to make anything you like (so long
as the elements are on hand) in addition to replicating themselves.
Thus, they are the robot equivalent of genetically engineered "pharm"
animals. Taylor called them "Santa Claus machines." In goes moon rock
and sunlight, and out comes steak and eggs.

Now comes the dark side. K. Eric Drexler, originally a space enthusiast
and L5 guy in the late 70's, comes across the idea of Taylor's big von
Neumann machines, and realizes they don't have to be large lumbering
clunky things, but can be made of clumps of atoms, much like most of
biology (which as you point out, is made of natural biological carbon
von Neumann machines). An inspirationw as Feynman's 1959 insite that
machines can be made as small as you like, until you get to atomic
scale.

So in 1980 Drexler proposes nano-sized Taylor-von Neumann machines not
only for space, but also for Earth useage. He calles these
self-replicating machines "assemblers" and co-opts a word that was then
floating around ("nanotechnology") to describe it all. Drexler's book
_Engines of Creation_ (1986) is a far-sighted look at both this small
self-replicating technology, and the bad things that could happen if it
went wrong (self-replicating small assemblers could reduce the
biosphere to nothing but self-replicating assemblers--- grey goo.)

And that's where we are. Except that since 1986 and Drexler,
"nanotechnology" has been coopted yet again to describe any kind of
engineering in the sub-micron scale, and no self-replication is
required. The government and the military are spending a lot of money
on sub-micron devices. Drexler and Taylor's ideas, still far ahead of
their time, are currently ignored in the mainstream. But their time
will come, as self-replication of these nano-devices becomes more and
more within their capabilities.

SBH