Mass drivers

Ron Menich wrote:
> Why not instead process the NEO raw material into finished
products right there at the NEO, and ship the finished products
back to HEO? Why is it that you prefer to ship raw material back
to HEO rather than finished products? Why not establish your
manufacturing facility at the NEO?

In a word: bootstrapping. Ship out a complete factory to make
finished goods?
Far easier to make some concrete rod, brick, or sheet, the rolled
& stamped metals for truss or plate, and wire -or whatever is
needed to build the track length. (Concrete in some form may be
best, if it can be made more simply than all metal structure. An
asteroid mine/ship certainly isn't mass-sensitive! Concrete
structure uses metals in their most effective ways, and uses bulk
rock to do most of the work.)
As I tried to report, ship out the basic parts needed to build up
the capability to build the track. Basic production facilities for the
bulk structure needed for the more complex facility to mass
produce the bigger track.
It all depends on whether this can be made less massive to
ship up from Earth & out to your rock, than the finished mass
driver. (Typical numbers show that over 90% of a production
facility is just dumb bulk structure. Similar numbers for the mass
driver.)

Far simpler is a solar oven based facility, to separate out the
metals & Ices, and just store them for the return trip, and use the
rock dust waste as reaction mass. (the above debate concerns
shipping the finished mass driver)
Typical projections show several hundred tons needed to ship
out, and 8-12 years to bring back about half of the 800m rock
undigested, and hundreds of k-tons+ of bagged raw metals &
ices.
You bring raw materials back to HEEO, because it's easier to
suport the numbers of people here, and to deal with shipping out
replacement parts & people to run a complete factory.

As with much of my meanderings, this stuff is being debated by
those qualified to design the mission. The fact that the AIAA &
SSI haven't decided for sure which way is best, shows that we
here can't decide. (Any more up-to-date info on what's being
decided?) We just need to keep all these possibilities in mind.

> John Frazer wrote,
>> "I'm still thinking of the asteroid retrieval mission. Latch onto
an 800 meter stony NEA, and drag it back...
>Send out the parts of the mass driver which aren't just rolled &
stamped metals and concrete & wires,and build up the track
length from local materials making up the bulk."