Incoming!!!

Hypothetically...

You've captured your stony-iron asteroid and parked it at the
Earth-moon L4 point. You've got mines and smelters producing tens of
megatons of refined metal annually, enough to meet a noticeable
fraction of Earth's demand for metals. The endless bounty of the space
is within humanity's grasp.

So...How do you land megatons of metal annually without resorting to
beanstalks, tethers, or anti-gravity? Just aerobrake big ingots and
let them drop into the ocean or an artificial receiver lake?

Mike Miller, Materials Engineer

"Mike Miller" wrote in message
om...
You've got mines and smelters producing tens of
megatons of refined metal annually, enough to meet a noticeable
fraction of Earth's demand for metals.

Wouldn't it make more sense economically to use the material where it is --
in space? After all, if you have a substantial enough infrastructure in
space to capture an asteroid, would that not imply that rather than giving
up all that kinetic energy (in fact, dumping a whole lot more into it to
drop it down the Earth's gravity well), it would be better to retain it and
use it a lot closer (in energy terms) to where it is to expand that
infrastructure and add to its capability?\

Jim McCauley
Mountain View CA

Mike Miller wrote:
Hypothetically...

You've captured your stony-iron asteroid and parked it at the
Earth-moon L4 point. You've got mines and smelters producing tens of
megatons of refined metal annually, enough to meet a noticeable
fraction of Earth's demand for metals. The endless bounty of the space
is within humanity's grasp.

So...How do you land megatons of metal annually without resorting to
beanstalks, tethers, or anti-gravity? Just aerobrake big ingots and
let them drop into the ocean or an artificial receiver lake?

Would simple steel spheres of around 2cm work?
Quite a lot of them of course.

(Mike Miller) writes:

Hypothetically...

You've captured your stony-iron asteroid and parked it at the
Earth-moon L4 point. You've got mines and smelters producing tens of
megatons of refined metal annually, enough to meet a noticeable
fraction of Earth's demand for metals. The endless bounty of the space
is within humanity's grasp.

So...How do you land megatons of metal annually without resorting to
beanstalks, tethers, or anti-gravity? Just aerobrake big ingots and
let them drop into the ocean or an artificial receiver lake?

One probably wouldn't use "big ingots," but aerobraking is not unreasonable.
One could either foam the metal or form it into a wide flat cone to increase
its frontal area per unit mass, so that it would decelerate at high altitude
without need for (much) ablative shielding (and if ablative shielding proved
necessary, it could be cheaply made out of slag). And since there is nothing
particularly "delicate" about a load of bulk refined metal, it might indeed
not be unreasonable to allow it to simply splash down at terminal velocity
in a large lake.


-- Gordon D. Pusch

perl -e '$_ = \n"; s/NO\.//; s/SPAM\.//; print;'

Mike Miller wrote:
So...How do you land megatons of metal annually without resorting to
beanstalks, tethers, or anti-gravity? Just aerobrake big ingots and
let them drop into the ocean or an artificial receiver lake?

Nothing really stopping you from forming the ingots as disk shaped blunt
reentry vehicles. Sure you have some mass disappearing during reentry,
but a cheap and reliable tug for the deorbit burn that can be
refurbished and sent back up completes the package. Ocean landing is the
least hazardous, but does contaminate the surfaces. Do a scheduled drop
of a series of very large reentry masses on a single day, then spend the
rest of the month retrieving them either the ocean surface or the ocean
floor depending on how bad of an impact. This allows you to do a not
heavily disruptive warning to mariners.

Fresh water lakes would be nice, but you're effectively dealing with an
unguided reentry which requires a big landing ellipse, and you may need
the lake to be somewhat deep in case of a bad impact, which increase
hazards and costs.

Junkboy

(Mike Miller) :

Hypothetically...

You've captured your stony-iron asteroid and parked it at the
Earth-moon L4 point. You've got mines and smelters producing tens of
megatons of refined metal annually, enough to meet a noticeable
fraction of Earth's demand for metals. The endless bounty of the space
is within humanity's grasp.

So...How do you land megatons of metal annually without resorting to
beanstalks, tethers, or anti-gravity? Just aerobrake big ingots and
let them drop into the ocean or an artificial receiver lake?

Mike Miller, Materials Engineer

Foam Metal or hollow shapes. If you aerobrake an metal object with a low
average density, you can send pure raw stock down to land near the processing
plant. Since the metal feedstock to the Earth-side plant is already
processed, it will take a lot less energy per pound/kilo of output compared
to processing ore, and the pure metal feedstock will also cut out a lot of
the pollution normally generated.

Earl Colby Pottinger


--
I make public email sent to me! Hydrogen Peroxide Rockets, OpenBeos,
SerialTransfer 3.0, RAMDISK, BoatBuilding, DIY TabletPC. What happened to
the time? http://webhome.idirect.com/~earlcp

Mike Miller wrote:
Hypothetically...

You've captured your stony-iron asteroid and parked it at the
Earth-moon L4 point. You've got mines and smelters producing tens of
megatons of refined metal annually, enough to meet a noticeable
fraction of Earth's demand for metals. The endless bounty of the space
is within humanity's grasp.

This has always fascinated me - why do people think there is a shortage
of metals here on earth that requires asteroid mining? The metal -
leaving the cost of asteroid capture aside for the moment - is not going
to be free, and increased availability will decrease prices.


So...How do you land megatons of metal annually without resorting to
beanstalks, tethers, or anti-gravity? Just aerobrake big ingots and
let them drop into the ocean or an artificial receiver lake?

Preferably, you would have found a way to get people to pay for these
materials without these leaving earth orbit, or even more, go to a
not much different orbit. So you sort of have to have lots of orbital
infrastructure first before it makes sense.


Mike Miller, Materials Engineer

--
Sander

+++ Out of cheese error +++

(Mike Miller) wrote in message . com...
So...How do you land megatons of metal annually without resorting to
beanstalks, tethers, or anti-gravity?

Why would you not resort to space tethers? If you are lowering things with
a rotating tether you can use the energy to bring stuff up. So lowering
metal to Earth would help you be able to bring things off of Earth.
You can make rotating tethers out of Spectra-2000, which is used
for fishing line. You could really make a reusable suborbital rocket
to match speed with the end of the tether. So why put tethers
with "beanstalks" or "anti-gravity"? A rotating tether is just
a rotating rope using existing rope materials. Why do you want
to avoid them? I am really puzzled that people don't take space
tethers much more seriously than anti-gravity. Please explain...

-- Vince

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~
Vincent Cate Space Tether Enthusiast
http://spacetethers.com/
Anguilla, East Caribbean http://offshore.ai/vince
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~

You have to take life as it happens, but you should try to make it
happen the way you want to take it. - German Proverb

In article ,
Mike Miller wrote:
So...How do you land megatons of metal annually without resorting to
beanstalks, tethers, or anti-gravity? Just aerobrake big ingots and
let them drop into the ocean or an artificial receiver lake?

In principle, you can just form it into suitable reentry shapes -- hollow
spheres might be good, you want something light enough that it decelerates
aerodynamically to near-zero terminal velocity -- and hard-land them in
some convenient location. It's probably better to just lease a big chunk
of desert rather than fooling around with water; you don't much care
whether they break on impact.

In practice, you may have a problem with nitrogen-oxide formation during
reentry, and possible adverse effects thereof on the ozone layer. This
is not a big deal for modest numbers of manned spacecraft, but aerodynamic
braking of megaton quantities of materials would be a real concern. Time
to warm up the rotating tethers.
--
MOST launched 30 June; science observations running | Henry Spencer
since Oct; first surprises seen; papers pending. |

Mike Miller opined

Hypothetically...

You've captured your stony-iron asteroid and parked it at the
Earth-moon L4 point. You've got mines and smelters producing tens of
megatons of refined metal annually, enough to meet a noticeable
fraction of Earth's demand for metals. The endless bounty of the space
is within humanity's grasp.

So...How do you land megatons of metal annually without resorting to
beanstalks, tethers, or anti-gravity? Just aerobrake big ingots and
let them drop into the ocean or an artificial receiver lake?

Form it into a big hollow sphere, with vacuum in the center. Make it big
enough so that the specific gravity is less than sea level air. Drop it into
Earth's atmosphere, wait for it to sink to ~300m and tow to where ever.


-ash
Cthulhu for President!
Why vote for a lesser evil?

From an old Analog story.