I see two classes of feasible scenario for mining NEA. I would
appreciate people's feedback on which they think is most plausible
and any flaws in logic, physics or engineering that I've made. Also,
I don't consider it feasible to move an entire asteroid. The kinetic
energy required for a mass of that huge size is mind moggling.

The first scenario is to send out a mining ship, process the
material and either send the ship and material back, or keep the
mining facility there doing its mining and refining, while the ship
heads back to earth-space.

The second scenario is one that I'm leaning in favor of. Send out a
ship with a mining facility, seeds of a mass driver and the seeds of
a power facility. Establish the facility, extract the material
needed to construct the main mass of the mass driver and the solar
power facility, integrate the earth-manufactured parts for these
devices, and then commence shipments to earth-space. After a while,
the crew departs back for earth.

Obviously, this second proposal is more complex. I envision a small
solar furnace, extracting the bulk materials required for the
manufacture of the systems. This shouldn't be too complex. It
wouldn't need to capture gases, so minimal storage would be
required. It has only one mission: process enough steel, etc to get
the system functional. The rest of the mined material will be
refined in earth-space.

So, here are my technical concerns. Can a mining/excavating system
run autonomously? I'm envisioning a territory is staked out and the
excavating units are bounded within that territory. They excavate
under some AI heuristic, head back to the processing center, release
their load into the mass driver processing unit, then head back to
mine more material. The dropped off material is weighed to a
standard mass, an orbit is computed, a variable velocity of launch
is applied.

So, how complex a system do you think we can leave unattended with
present day techology? I guess this question applies to self-repair
capabilities. I don't know the state of the art in this engineering
field. Can anyone help? No future guesswork please. I can imagine
things too, but for now, I don't really know what is capable.

Another problem is if the the mass driver is attached to the NEO
then as the NEO progresses in its orbit the mass driver will become
oriented in the wrong direction to fire a payload to earth-space. A
solution I foresee is that downrange of the mass driver is a
particle beam cannon which applies the correct amount of energy to
the "in-flight" payload to alter its course. This seems problematic,
but I'm not sure. Or the mass driver can be pivotable. So it is off
of the NEO and the payload is sent to it on conveyor belt. The mass
driver is oriented to allow the payload to achieve proper orbit. But
how do we mitigate the forces of the payload launch which are acting
against the point of attachment between the mass driver and the
NEO? Perhaps we don't attach the mass driver to the NEO. The
payloads are lobbed up to the mass driver but we'd still be left
with the mass driver changing its postion relative to the NEO. So it
would need some propellant to bring it back into position. I tend to
favor the mass driver being off of the NEO, because now the launches
aren't confined to the plane of the NEO. But I'm still left with a
lot of feasability questions. I'd very much appreciate people's
thoughts on the specifics of making such a scheme work.

Now when the payloads are appraoching earth-space, the question
becomes how much has the course varied over the weeks, months, or
years of transit? I've seen reference to a lunar mass driver being
able to hit a target within 10+ meters. But over the course of tens
of millions of kilometers, the error may grow to a 100+ kilometers,
so, now what? If the particle beam guidance system works, then how
about a series of accelerators stationed around the perimeter of the
100 km zone of error. The propellant needed to keep these
accelerators on station should be relatively easy to provide
considering their proximity to earth-space. Radar guidance could
establish the trajectory of the incoming payload, and the correcting
force vectors can be applied from any number of the accelerators. At
the same time they could be applying energy to slow the payload's
velocity. The payload is thus guided to a mass catcher and taken to
the Materials Processing Facility. Is this achievable? Or is this
science fiction at the present? I know we don't have this equipment
now, but is the technology there yet?

I'm really drawn to the efficiency of mass driver propulsion
compared to the inefficiency of rocket propulsion but I see it as
really pushing our technological limits. How much of what I've
proposed is within out means, and how much am I way off base on?

One last thought, I'd rather send the NEO material to earth
incrementally, rather than moving the whole mass of the asteroid,
consuming its mass for propulsion and not seeing the material reach
earth for many years. At least this way material is reaching earth
incrementally, even though it creates all sorts of guidance problems.

Thanks for your feedback.

> I see two classes of feasible scenario for mining
NEA. I would
> appreciate people's feedback on which they think is
most plausible
> and any flaws in logic, physics or engineering that
I've made. Also,

There have been some discusisons of similar issues
previously on this
list, in July 2001 and October 2001. I have
forwarded to
you personally a couple of messages whihc I retained

> I don't consider it feasible to move an entire
asteroid. The kinetic
> energy required for a mass of that huge size is mind
moggling.
>

We only to need to move as much as we need to move.

>
> The first scenario is to send out a mining ship,
process the
> material and either send the ship and material back,
or keep the
> mining facility there doing its mining and refining,
while the ship
> heads back to earth-space.
>

It depends on what you mean by processing. The cost
of sending ships
to NEO's is higher than lkeaving them in the
Earth-Moon orbital
space. And the end user market will be in
Earth-Moon orbital space.

So we want to send the minimum amount of equipment to
the NEO as
possible. There is no advantage to doing
processing at the
asteroid. So it is necessary simply to recover raw
materials from
the asteroid, then bring them back to Earth-Moon space
for processing.

Another major consideration is that the trip time to
the NEO is several
months. During this time the facftory cannot process
anyhting.
Downtime is wasted time, and expensive. Hence we
want to keep the
factory in near-Earth/Moon space where it can be in
continuous
operation, fed by a continuous stream of raw NEO
material.

> The second scenario is one that I'm leaning in favor
of. Send out a
> ship with a mining facility, seeds of a mass driver
and the seeds of
> a power facility. Establish the facility, extract
the material
> needed to construct the main mass of the mass driver
and the solar
> power facility, integrate the earth-manufactured
parts for these
> devices, and then commence shipments to earth-space.
After a while,
> the crew departs back for earth.
>

Mass driver might not be the best propulsion method.
Previously we
have discussed using a Hall thruster system, with
oxygen as its reaction
mass. This has a much higher specific impulse
(exhaust velocity) than
a mass driver. The oxygen could be produced at the
asteroid after
arrival.

>
> Obviously, this second proposal is more complex. I
envision a small

No, this is not obvious. It could be a lot simpler
than sending a
factory to a NEO, a factory/processing facility coul;d
be very complex
inddedindeed.

>
> So, here are my technical concerns. Can a
mining/excavating system
> run autonomously? I'm envisioning a territory is
staked out and the

Well, right now it is all vaporware, so the answer is
yes, of course.
Vaporware can do anything.

>
> excavating units are bounded within that territory.
They excavate
> under some AI heuristic, head back to the processing
center, release

Sounds rather complicated, I expect there are simpler
ways of doing it.

>
> their load into the mass driver processing unit,
then head back to
> mine more material. The dropped off material is
weighed to a
> standard mass, an orbit is computed, a variable
velocity of launch
> is applied.
>

Well this is where you have a problem. You need to
start thinking
about launch windows. You cannot launch whenever
you want, there are
orbital constraints.

>
> So, how complex a system do you think we can leave
unattended with
> present day techology? I guess this question applies
to self-repair

Present day technology ? Which technology would that
be ?

>
> capabilities. I don't know the state of the art in
this engineering
> field. Can anyone help? No future guesswork please.
I can imagine
> things too, but for now, I don't really know what is
capable.
>

State of the art ? It is all theoretical back of the
envelope stuff.
No serious design work that I know of.

>
> Another problem is if the the mass driver is
attached to the NEO
> then as the NEO progresses in its orbit the mass
driver will become
> oriented in the wrong direction to fire a payload to
earth-space. A

No. You are making assumptions here.

First off, the asteroid will be spinning. So to use
a mass driver you
need a method to despin the asteroid and/or reorient
the spin axis.
Whatever method you use for this can be used to sterr
the entire
asteroid during flight, thus pointing the mass driver
thrust in any
desired direction.

> solution I foresee is that downrange of the mass
driver is a
> particle beam cannon which applies the correct
amount of energy to
> the "in-flight" payload to alter its course. This
seems problematic,

Not really. You are inventing a problem where none
really exists.

> but I'm not sure. Or the mass driver can be
pivotable. So it is off

No, no, this is completely unecessary.

Victoria, permit me to make a general observation:

You sometimes over-analyse very complex solutions to
non-existent
problems.
Whilst you have been ignoring more important and more
basic system level
issues.

> of the NEO and the payload is sent to it on conveyor
belt. The mass
> driver is oriented to allow the payload to achieve
proper orbit. But

What do you mean by proper orbit ? You do not seem
to understand the
launch window issues.

Do you know what a Hohman interplanetary transfer
orbit is ?
If not, go and read up on before continuing this
discussion.

> favor the mass driver being off of the NEO, because
now the launches
> aren't confined to the plane of the NEO. But I'm
still left with a

???

>
> Now when the payloads are appraoching earth-space,
the question
> becomes how much has the course varied over the
weeks, months, or
> years of transit? I've seen reference to a lunar
mass driver being

???
Do you understand the Hohman transfer orbit ?
Do you understand how this differs from a low thrust
trajectory ?

> able to hit a target within 10+ meters. But over the
course of tens
> of millions of kilometers, the error may grow to a
100+ kilometers,

The orbit is tracked using nmavigations systems such
as INS and radar.
The thrust vector of the mass driver/hall thruster is
varied to correct
orbital errors.

> so, now what? If the particle beam guidance system
works, then how
> about a series of accelerators stationed around the
perimeter of the
> 100 km zone of error. The propellant needed to keep
these
> accelerators on station should be relatively easy to
provide

Which "station" are you refering to ?

> considering their proximity to earth-space. Radar
guidance could
> establish the trajectory of the incoming payload,
and the correcting
> force vectors can be applied from any number of the
accelerators. At

Incoming to where ?
Once again you are over-analyzing a rather complex
solution to a
poorly-defined and probably fairly simple problem.

> the same time they could be applying energy to slow
the payload's
> velocity. The payload is thus guided to a mass
catcher and taken to
> the Materials Processing Facility. Is this
achievable? Or is this
> science fiction at the present? I know we don't have
this equipment
> now, but is the technology there yet?
>

Yes it is achievable (vaporware can do anything).

Yes it is science ficiton right now.

> I'm really drawn to the efficiency of mass driver
propulsion
> compared to the inefficiency of rocket propulsion
but I see it as

Actually mass drivers are very inefficienct as
"rockets".
Brian O'Leary caclulated many years ago that about
half of the asteroid
would be consumed and expelled as reaction mass during
the trip home.

A Hall-thrust has a much higher specific impulse than
a mass driver, and
the amount of asteroid mass consumed would be orders
of magnitude less.

But effciency is not very important, what really
matters is money.
We need a cheap solution, if it uses up half the
asteroid on the way
that is probably fine.

> really pushing our technological limits. How much of
what I've
> proposed is within out means, and how much am I way
off base on?
>

It is all vaporware, no serious design work has been
done on any of this
stuff.

> One last thought, I'd rather send the NEO material
to earth
> incrementally, rather than moving the whole mass of
the asteroid,

That would be fine. You need to pay attention to the
launch
windows. There are hundreds or thousands of
asteroids to choose
from. You do not need to return to the same asteroid
each time. You
simply go to which ever one has the most favorable
launch window at the
time when you are ready to amke the trip.

> consuming its mass for propulsion and not seeing the
material reach
> earth for many years. At least this way material is
reaching earth
> incrementally, even though it creates all sorts of
guidance problems.
>

The guidance problems are almost trivial compared to
the overall cost of
the mission.

>
> > I see two classes of feasible scenario for mining
> NEA. I would

Victoria,

Many of the design issues you raise have been
discussed at the innertransit web site, run by
Mitchell James mejames@...

I suggest you head over there and sign up, it is free.

http://www.innertransit.org/

and the related website:

http://www.innertransit.net/

You will find some discussions relating to Tethered
Momentum Transfer Intercept which discusses issues
relating to taking advantage of the asteroid spin as
free energy.

Cheers,

Charles R.

>
> > I see two classes of feasible scenario for mining
> NEA. I would
> > appreciate people's feedback on which they think is
> most plausible
> > and any flaws in logic, physics or engineering that
> I've made. Also,
>
> There have been some discusisons of similar issues
> previously on this
> list, in July 2001 and October 2001. I have
> forwarded to
> you personally a couple of messages whihc I retained
>
> > I don't consider it feasible to move an entire
> asteroid. The kinetic
> > energy required for a mass of that huge size is mind
> moggling.
> >
> We only to need to move as much as we need to move.
>
> > The first scenario is to send out a mining ship,
> process the
> > material and either send the ship and material back,
> or keep the
> > mining facility there doing its mining and refining,
> while the ship
> > heads back to earth-space.
> >
> It depends on what you mean by processing. The cost
> of sending ships
> to NEO's is higher than lkeaving them in the
> Earth-Moon orbital
> space. And the end user market will be in
> Earth-Moon orbital space.

I'm in complete agreement with you here. By processing, I only meant
the minimum amount of work required to prepare the shipment for
transit to earth. Earth orbit is the proper place to have the
sophisticated value-added machary and processes.

>
> So we want to send the minimum amount of equipment to
> the NEO as
> possible. There is no advantage to doing
> processing at the
> asteroid. So it is necessary simply to recover raw
> materials from
> the asteroid, then bring them back to Earth-Moon space
> for processing.

If some material requires NO processing to prepare it for transit,
then of course that's the way to go. Without looking into the
specifics of materials processing science, I'm just allowing for the
possibility of minimum processing to prepare for transit, if it is
argued that that is the optimum solution. The processing could
simple be to confine the shipment in some manner, i.e. sintering,
bagging, loading into containers, etc.
>
> Another major consideration is that the trip time to
> the NEO is several
> months. During this time the facftory cannot process
> anyhting.
> Downtime is wasted time, and expensive. Hence we
> want to keep the
> factory in near-Earth/Moon space where it can be in
> continuous
> operation, fed by a continuous stream of raw NEO
> material.

Absolutely agree.
>
> > The second scenario is one that I'm leaning in favor
> of. Send out a
> > ship with a mining facility, seeds of a mass driver
> and the seeds of
> > a power facility. Establish the facility, extract
> the material
> > needed to construct the main mass of the mass driver
> and the solar
> > power facility, integrate the earth-manufactured
> parts for these
> > devices, and then commence shipments to earth-space.
> After a while,
> > the crew departs back for earth.
> >
> Mass driver might not be the best propulsion method.
> Previously we
> have discussed using a Hall thruster system, with
> oxygen as its reaction
> mass. This has a much higher specific impulse
> (exhaust velocity) than
> a mass driver. The oxygen could be produced at the
> asteroid after
> arrival.
>
> > Obviously, this second proposal is more complex. I
> envision a small
>
> No, this is not obvious. It could be a lot simpler
> than sending a
> factory to a NEO, a factory/processing facility coul;d
> be very complex
> inddedindeed.
>
> > So, here are my technical concerns. Can a
> mining/excavating system
> > run autonomously? I'm envisioning a territory is
> staked out and the
>
> Well, right now it is all vaporware, so the answer is
> yes, of course.
> Vaporware can do anything.

I hoped it wasn't vaporware. That's a little sad. I thought some
research would have been conducted on this topic and that long-term
and knowledgeable members of this list would be able to point me to
that information.

Vaporware is so depressing. I like to dream like the next guy, but I
really like to base my HF vision on technological certainties.
>
> > excavating units are bounded within that territory.
> They excavate
> > under some AI heuristic, head back to the processing
> center, release
>
> Sounds rather complicated, I expect there are simpler
> ways of doing it.
>
> > their load into the mass driver processing unit,
> then head back to
> > mine more material. The dropped off material is
> weighed to a
> > standard mass, an orbit is computed, a variable
> velocity of launch
> > is applied.
> >
> Well this is where you have a problem. You need to
> start thinking
> about launch windows. You cannot launch whenever
> you want, there are
> orbital constraints.

If I'm reading your answer correctly, then I think you've mis-
interpreted what I wrote. I didn't mean to imply the standard usage
of a mass driver with respect to NEO, which is to use the partial
mass of the NEO to propel the NEO to earth-space. What I'm proposing
is that the orbit of the NEO not be changed. The mass driver uses a
small SPS traveling in the orbit with the NEO, and that electrical
energy is used to shoot payloads continuously to earth-space.

Granted, the traditional use of a mass driver would be very
inefficient with respect to specific impulse. But the delta-v that
can be imparted into the payload can be very significant. It would
be a function of the acceleration, energy used, and track length.
With track length being fixed, the accelration and energy used are
the variables used to impart different delta-v.

The mass driver doesn't suffer from the limitations of the rocket
equation, where it has to start the voyage with all of its fuel and
accelerate that fuel.

I don't claim expertise on Hohlmann orbits, but my understanding is
that such an orbit is one in which the minimal delta-v is required
to reach the destination, but the trade-off is time in transit.

Further, my understanding is that Hohlmann orbits are not the ONLY
orbits that can be plotted. If the mission planner is willing to
consider higher delta-v, then more windows are opened, and further,
if delta-v does not become a consideration, then there is always an
orbit that can be plotted.

So, with a stationary mass driver propelling payloads, but not the
NEO itself, no two launches would have the same orbit. Granted the
changes would be incremental over time because the delta-v and
orbital inclinations will be changing.
>
> > So, how complex a system do you think we can leave
> unattended with
> > present day techology? I guess this question applies
> to self-repair
>
> Present day technology ? Which technology would that
> be ?

I have no idea. I know that the members of this list are drawn from
various disciplines and interests and I was hoping someone who KNEW
something about the state of the art in this field could enlighten
me. I can ask the question, perhaps innocently, because I'm not
constrained by the limits of knowing the current limitations, and
someone more knowledgeable than me could give me a few pointers to
the answers. I believe that listmembers include people working in
areospace, computers, academia, etc.

I can contribute in my own field which is finance/marketing where I
have a Ph.D, but there is very little intersect between my own
expertise and the topics of this list :) I'm here to learn and
engage with others on a topic that interest me as a layman. If
you're curious about some of my thoughts on FAR FUTURE economic
issues relating to Habitats, pop over to Spacesettlers group at

>
> > capabilities. I don't know the state of the art in
> this engineering
> > field. Can anyone help? No future guesswork please.
> I can imagine
> > things too, but for now, I don't really know what is
> capable.
> >
> State of the art ? It is all theoretical back of the
> envelope stuff.
> No serious design work that I know of.
>
> > Another problem is if the the mass driver is
> attached to the NEO
> > then as the NEO progresses in its orbit the mass
> driver will become
> > oriented in the wrong direction to fire a payload to
> earth-space. A
>
> No. You are making assumptions here.
>
> First off, the asteroid will be spinning. So to use
> a mass driver you
> need a method to despin the asteroid and/or reorient
> the spin axis.
> Whatever method you use for this can be used to sterr
> the entire
> asteroid during flight, thus pointing the mass driver
> thrust in any
> desired direction.

I assumed that one of the first matters to be dealt with would be to
despin the asteroid. As I stated above, I'm not proposing moving the
entire asteroid, but shooting payloads.

Here are my assumptions. The greater a delta-v that is achievable,
the greater the number of viable orbits there will be. The Holhmann
orbit is not the only one to consider, even though it is most
efficient with respect to delta-v.

The mass driver will be able to impart vairaible delta-v to the
payload and the amss driver must be aimable.

>
> > solution I foresee is that downrange of the mass
> driver is a
> > particle beam cannon which applies the correct
> amount of energy to
> > the "in-flight" payload to alter its course. This
> seems problematic,
>
> Not really. You are inventing a problem where none
> really exists.

I don't understand. My assumption is that over a sufficent range,
any error introduced into the payload launch orbit can be detected
and corrected. I'm not assuming that the orbit will be bang on. Can
it be so accurate that no rbital correction is required?

>
> > but I'm not sure. Or the mass driver can be
> pivotable. So it is off
>
> No, no, this is completely unecessary.
>
> Victoria, permit me to make a general observation:
>
> You sometimes over-analyse very complex solutions to
> non-existent
> problems.
> Whilst you have been ignoring more important and more
> basic system level
> issues.

That comes from not knowing what the hell I'm talking about. :) and
having just a college level understanding of physics and chemistry,
and less so of engineering. Remember, a little knowledge is
dangerous :)
>
> > of the NEO and the payload is sent to it on conveyor
> belt. The mass
> > driver is oriented to allow the payload to achieve
> proper orbit. But
>
> What do you mean by proper orbit ? You do not seem
> to understand the
> launch window issues.
>
> Do you know what a Hohman interplanetary transfer
> orbit is ?
> If not, go and read up on before continuing this
> discussion.
>
> > favor the mass driver being off of the NEO, because
> now the launches
> > aren't confined to the plane of the NEO. But I'm
> still left with a
>
> ???
>
> > Now when the payloads are appraoching earth-space,
> the question
> > becomes how much has the course varied over the
> weeks, months, or
> > years of transit? I've seen reference to a lunar
> mass driver being
>
> ???
> Do you understand the Hohman transfer orbit ?
> Do you understand how this differs from a low thrust
> trajectory ?
>
> > able to hit a target within 10+ meters. But over the
> course of tens
> > of millions of kilometers, the error may grow to a
> 100+ kilometers,
>
> The orbit is tracked using nmavigations systems such
> as INS and radar.
> The thrust vector of the mass driver/hall thruster is
> varied to correct
> orbital errors.

I see your point completely if the payload coming to earth-space had
its own means of propulsion. I'm proposing just a hunk of rock
coming in and how will we guide it and stop it.

Just as you said that it make most sense to have the refining and
processing equipment in earth orbit (completely agree) I hold the
opinion that it makes most sense to send dumb payloads on their
journeys and leave ONE propulsive device (mass driver at NEO) at the
departure point, and have ONE guidance and deceleration mechanism at
earth orbit. Of course, I'm presuming the volume of material
arriving from NEO is sufficient to warrant a large investment in
such infrastructure. The alternative, more traditional perspective
is to have a large number of rocket units delivering payload, and
then deadheading back to the NEO to pick up another payload. Seems
very inefficient given a large number of shipments.
>
> > so, now what? If the particle beam guidance system
> works, then how
> > about a series of accelerators stationed around the
> perimeter of the
> > 100 km zone of error. The propellant needed to keep
> these
> > accelerators on station should be relatively easy to
> provide
>
> Which "station" are you refering to ?

A region of space that is the destination point of the orbit. This
region is defined by a margin of error in guidance. To elaborate;
how much error is introduced into the orbit over a journey of
50,000,000km with no ability to introduce orbital correction burns?
So, the payload arrives within a larger region rather than a smaller
region, or point. The station is the area of that error. The
perimeter of the station is where orbital correction mechanisms are
placed.

>
> > considering their proximity to earth-space. Radar
> guidance could
> > establish the trajectory of the incoming payload,
> and the correcting
> > force vectors can be applied from any number of the
> accelerators. At
>
> Incoming to where ?
> Once again you are over-analyzing a rather complex
> solution to a
> poorly-defined and probably fairly simple problem.
>
> > the same time they could be applying energy to slow
> the payload's
> > velocity. The payload is thus guided to a mass
> catcher and taken to
> > the Materials Processing Facility. Is this
> achievable? Or is this
> > science fiction at the present? I know we don't have
> this equipment
> > now, but is the technology there yet?
> >
> Yes it is achievable (vaporware can do anything).
>
> Yes it is science ficiton right now.
>
> > I'm really drawn to the efficiency of mass driver
> propulsion
> > compared to the inefficiency of rocket propulsion
> but I see it as
>
> Actually mass drivers are very inefficienct as
> "rockets".
> Brian O'Leary caclulated many years ago that about
> half of the asteroid
> would be consumed and expelled as reaction mass during
> the trip home.
>
> A Hall-thrust has a much higher specific impulse than
> a mass driver, and
> the amount of asteroid mass consumed would be orders
> of magnitude less.
>
> But effciency is not very important, what really
> matters is money.
> We need a cheap solution, if it uses up half the
> asteroid on the way
> that is probably fine.

Agree with you completely. I'd rather see a materials processing
facility dealing with material coming in on a steady basis ( a
stream of payloads coming in continuously after being launched from
the NEO via mass driver), rather than in a batch format (huge load
arrives from NEO via rocket) which in turn is more preferrable to
delivering a whole NEO to the the MPF every decade.

>
> > really pushing our technological limits. How much of
> what I've
> > proposed is within out means, and how much am I way
> off base on?
> >
> It is all vaporware, no serious design work has been
> done on any of this
> stuff.
>
> > One last thought, I'd rather send the NEO material
> to earth
> > incrementally, rather than moving the whole mass of
> the asteroid,
>
> That would be fine. You need to pay attention to the
> launch
> windows. There are hundreds or thousands of
> asteroids to choose
> from. You do not need to return to the same asteroid
> each time. You
> simply go to which ever one has the most favorable
> launch window at the
> time when you are ready to amke the trip.

Not planning on return voyages. What I'm wondering about is whether
it is feasible to establish a launch facility on a NEO and
continuously launch from it and vary the payloads delta-v and orbit
over time as the orbit of the NEO precesses?

If I'm reading your answer correctly, then I think
you've mis-
interpreted what I wrote. I didn't mean to imply the
standard usage
of a mass driver with respect to NEO, which is to
use the partial
mass of the NEO to propel the NEO to earth-space.
What I'm proposing
is that the orbit of the NEO not be changed. The
mass driver uses a
small SPS traveling in the orbit with the NEO, and
that electrical
energy is used to shoot payloads continuously to
earth-space.

The same problem applies.

You cannot continuously shoot payloads from a NEO to
the Earth. You can only do so at discrete
short-lived
windows of opportunity when the relative positions of
the Earth and NEO are optimal.

Further, my understanding is that Hohlmann orbits
are not the ONLY
orbits that can be plotted. If the mission planner
is willing to
consider higher delta-v, then more windows are
opened, and further,
if delta-v does not become a consideration, then
there is always an
orbit that can be plotted.

That much is true. It depends on the numbers. It is
possible that at non-optimal alignments
100kg of asteroid material must be expended to get 1
kg of material to the vicinity of Earth.

>
> > So, how complex a system do you think we can
leave
> unattended with
> > present day techology? I guess this question
applies
> to self-repair
>
> Present day technology ? Which technology would
that
> be ?

I have no idea. I know that the members of this list
are drawn from
various disciplines and interests and I was hoping
someone who KNEW
something about the state of the art in this field
could enlighten
me. I can ask the question, perhaps innocently,
because I'm not

My response was meant to be ironic. There is no
signifcant technology developed in this area.
It is all vaporware and speculation at this point.
Robotic mining systems in use on Earth today are not
suited for
operations in space.

I can contribute in my own field which is
finance/marketing where I
have a Ph.D, but there is very little intersect
between my own

Hah ! Well it sure would be nice to get some funding
for more research in these areas. Perhaps you can
advise in
the all-important area of business planning.

>

I assumed that one of the first matters to be dealt
with would be to
despin the asteroid. As I stated above, I'm not
proposing moving the
entire asteroid, but shooting payloads.

Actually, the spin could be used to advantage.
Instead of using a mass driver, simply reel out
payloads at the end of
a long tether, and let it go. If a strong enough
tether is available a significant velocty could be
achieved.

The mass driver will be able to impart vairaible
delta-v to the
payload and the amss driver must be aimable.

The spin of the asteroid itself could be used to aim a
mass driver.

>
> > solution I foresee is that downrange of the mass
> driver is a
> > particle beam cannon which applies the correct
> amount of energy to
> > the "in-flight" payload to alter its course.
This
> seems problematic,
>

I am not sure how that would work.

I see your point completely if the payload coming to
earth-space had
its own means of propulsion. I'm proposing just a
hunk of rock
coming in and how will we guide it and stop it.

OK, I see what you mean. I guess a manouverable
catcher would be required to rendezvous with the
incoming
stream of material at near-Earth space.

Not planning on return voyages. What I'm wondering
about is whether
it is feasible to establish a launch facility on a
NEO and
continuously launch from it and vary the payloads
delta-v and orbit
over time as the orbit of the NEO precesses?

Theoretically possible. Many practical problems
need to be researched.

> Further, my understanding is that Hohlmann orbits
> are not the ONLY
> orbits that can be plotted. If the mission planner
> is willing to
> consider higher delta-v, then more windows are
> opened, and further,
> if delta-v does not become a consideration, then
> there is always an
> orbit that can be plotted.
>
> That much is true. It depends on the numbers. It is
> possible that at non-optimal alignments
> 100kg of asteroid material must be expended to get 1
> kg of material to the vicinity of Earth.
>

We're still crossing wires here. Why 100kg of material to launch 1
kg payload? What I'm prosposing is payload launched by electrical
energy alone. We don't need the 100kg mass at all. Just lots of
energy. Think of how the larnar mass-drivers are proposed to
function. No lunar mass is used for propellant. That's exactly what
I'm proposing.

Consider that the lunar mass driver will be launching payloads at an
escape velocity of 3000 m/s. Some NEO's will require an optimum
delta-v considerably less than that. As launching progesses beyond
the optimum window, the delta-v will continually increase. At some
point in the orbit of that NEO, the energy expended (KE=m*V2) will
be so great that it'll make sense to cease launching until the orbit
of the NEO comes back to a minimal point where it once again starts
to make economic sense to re-commence launching.

You know, in order to facilitate a continuous stream of payloads
arriving at the Manufacturing Facility, we might consider payload
launches up to a delta-v of 7000 m/s where the holhmann orbit could
be achieved at 1000 m/s. The economic analysis is something I'm
comfortable with, it's the technology and the physics that I'm
exploring.

>
> > > So, how complex a system do you think we can
> leave
> > unattended with
> > > present day techology? I guess this question
> applies
> > to self-repair
> >
> > Present day technology ? Which technology would
> that
> > be ?
>
> I have no idea. I know that the members of this list
> are drawn from
> various disciplines and interests and I was hoping
> someone who KNEW
> something about the state of the art in this field
> could enlighten
> me. I can ask the question, perhaps innocently,
> because I'm not
>
> My response was meant to be ironic. There is no
> signifcant technology developed in this area.
> It is all vaporware and speculation at this point.
> Robotic mining systems in use on Earth today are not
> suited for
> operations in space.
>
> I can contribute in my own field which is
> finance/marketing where I
> have a Ph.D, but there is very little intersect
> between my own
>
> Hah ! Well it sure would be nice to get some funding
> for more research in these areas. Perhaps you can
> advise in
> the all-important area of business planning.

I've seen business plans for space ventures. Most of them were
submitted from space-enthusiasts, not business people. That said,
many were very pie-in-the-sky. Some were very engineering and
physics based and therefore more realistic, but had trouble with the
issue of how to make money.

Personally, I think the breakthrough will come when there is a
technology, service, process that CANNOT be done on earth, where the
substitution effect doesn't apply and where prfitable demand exists.
Then the only alternative is to get it into space and work to build
that market. I don't really know what that magic bullet wil be. It's
not SPS yet. Too much infrastructure required and there are
substitutes for SPS energy.

For isntance, come up with a cure for cancer vacine which must be
manufactured in a zero-g vacuum and requires a large infrastructure
in space and now you've got a solid footing to start space
industrialization. There is no substitute that can be manufactured
on earth. The demand for the vacine would be huge. The political
costs of not developing it would be disasterous. People would be
willing to pay a lot for it. But as soon as a substitute can be
developed on earth, the foundations will crumble.

>

>
> We're still crossing wires here. Why 100kg of
material to launch 1
> kg payload? What I'm prosposing is payload launched
by electrical
> energy alone. We don't need the 100kg mass at all.
Just lots of
> energy. Think of how the larnar mass-drivers are
proposed to
> function. No lunar mass is used for propellant.
That's exactly what
> I'm proposing.
>

OK

> Consider that the lunar mass driver will be
launching payloads at an
> escape velocity of 3000 m/s. Some NEO's will require
an optimum
> delta-v considerably less than that. As launching
progesses beyond

It might need either more or less velocity depending
on the asteroid's orbit and its position versus the
optimum launch window.

> the optimum window, the delta-v will continually
increase. At some
> point in the orbit of that NEO, the energy expended
(KE=m*V2) will
> be so great that it'll make sense to cease launching
until the orbit

The only limit will be in the mass driver, what is the
maximum velocity it can launch.
To some extent it might be possible to reduce the
payload weight, increase the acceleration and thus
achieve higher velocity. Again, the utlimate limit o
nthe velocity the mass driver can achieve is a
combination of the length and the switching speed of
the SCRs.

> of the NEO comes back to a minimal point where it
once again starts
> to make economic sense to re-commence launching.
>

If the velocity required exceeds the velocity
capability of the mass driver, then there is no point
in launching anything until the conditions improve.

> You know, in order to facilitate a continuous stream
of payloads
> arriving at the Manufacturing Facility, we might
consider payload

The continuous stream does not need to come from a
single asteroid, of course. It can be comprised of
materials from multiple NEOs.

>
> Personally, I think the breakthrough will come when
there is a
> technology, service, process that CANNOT be done on
earth, where the
> substitution effect doesn't apply and where
prfitable demand exists.

I cannot imagine what such a thing could be. SPS and
tourism are the only markets which have the potential
for massive industrial expansion in space.

> Then the only alternative is to get it into space
and work to build
> that market. I don't really know what that magic
bullet wil be. It's
> not SPS yet. Too much infrastructure required and
there are
> substitutes for SPS energy.
>

Yes. Although I would argue that costs of fossil
fuels are artificially low. The price charged for
fuel at the pump does not include the taxpayer cost of
the US military, about $500 billion per year
(includes DOD, DOE and VA), which is mostly to assure
the security of our oil supplies - after all that is
primarily what the war on terrorism is really about.

And the present price of fossil fuels ignores the
future cost of climate change and economic disruption.

And the cost of nuclear power ignores the future
cleanup cost of nuclear waste, and the additional
military cost of keeping it safe from, terrorists.

For a few per cent of the military budget we could
develop SPS, and make the western world completely
independent of islamic oil. That would change the
global balance of power, and allow a considerably
downsized military.

> For isntance, come up with a cure for cancer vacine
which must be
> manufactured in a zero-g vacuum and requires a large
infrastructure
> in space and now you've got a solid footing to start
space
> industrialization. There is no substitute that can
be manufactured

I hardly think so. Vaccines are manufactured in
quantities of a couple of tons per year.
This needs little in the way of expanded
infrastructure, such an operation could probably be
housed within the existing ISS.

> > >
> > > > solution I foresee is that downrange of the
mass
> > > driver is a
> > > > particle beam cannon which applies the
correct
> > > amount of energy to
> > > > the "in-flight" payload to alter its course.
> > This
> > > seems problematic,
> > >
> > I am not sure how that would work.
> >

Again, I am not sure how such a system wolod work.

It might be most practical to attach a thruster or a
mini-tug to every payload launched by the mass driver.
This would permit in-course corrections.

Note that launching from non-ideal orbital positions
would not only result in higher launching velocity
requirement, it would also result in hgiher braking
velocity reequirement at the desitination.

>> The only limit will be in the mass driver, what is the
> maximum velocity it can launch.
> To some extent it might be possible to reduce the
> payload weight, increase the acceleration and thus
> achieve higher velocity. Again, the utlimate limit o
> nthe velocity the mass driver can achieve is a
> combination of the length and the switching speed of
> the SCRs.

Yes. Very good point. Thank you. Another variable that can be used
in the computation on whether to launch or not.

> > of the NEO comes back to a minimal point where it
> once again starts
> > to make economic sense to re-commence launching.

>
> The continuous stream does not need to come from a
> single asteroid, of course. It can be comprised of
> materials from multiple NEOs.

Absolutely. Have your crew take the equipment there once. Set it up
and let it run while the NEO is in optimum launch phase in its
orbit. Every once in a while send out a crew to effect repairs. Do
this for a number of NEO.

This whole scenario presupposes huge volumes of material. The
infrastructure isn't necessary if all you want is 1000 tonnes of
something. Better to do it with a rocket in that case. But 100,000
tons, maybe a 1,000,000 then it may be worth going this approach.

> I cannot imagine what such a thing could be. SPS and
> tourism are the only markets which have the potential
> for massive industrial expansion in space.

That's the point I made in my spacesettlers post "If we build it
will they come." Our thinking is constrained by our environment.
Who would have thought of radio or TV when a method for creating
vacuum was devised. What process, invention awaits us which is
tailor made for variable-g, hard radiation, no atmosphere
environment. How will our scientist's thinking change when that is
the environment that is only a few meters below their feet? When
they want to do an experiment in that environment, it'll be cheap
access, no jockeying for position for space launch. It'll be harder
for them to study the earth environment for up close, though their
high position should give them a different vantage point for
studying some earth phenomenom.

>
> > Then the only alternative is to get it into space
> and work to build
> > that market. I don't really know what that magic
> bullet wil be. It's
> > not SPS yet. Too much infrastructure required and
> there are
> > substitutes for SPS energy.
> >
> Yes. Although I would argue that costs of fossil
> fuels are artificially low. The price charged for
> fuel at the pump does not include the taxpayer cost of
> the US military, about $500 billion per year
> (includes DOD, DOE and VA), which is mostly to assure
> the security of our oil supplies - after all that is
> primarily what the war on terrorism is really about.
>
> And the present price of fossil fuels ignores the
> future cost of climate change and economic disruption.
>
> And the cost of nuclear power ignores the future
> cleanup cost of nuclear waste, and the additional
> military cost of keeping it safe from, terrorists.
>
> For a few per cent of the military budget we could
> develop SPS, and make the western world completely
> independent of islamic oil. That would change the
> global balance of power, and allow a considerably
> downsized military.
>
> > For isntance, come up with a cure for cancer vacine
> which must be
> > manufactured in a zero-g vacuum and requires a large
> infrastructure
> > in space and now you've got a solid footing to start
> space
> > industrialization. There is no substitute that can
> be manufactured
>
> I hardly think so. Vaccines are manufactured in
> quantities of a couple of tons per year.
> This needs little in the way of expanded
> infrastructure, such an operation could probably be
> housed within the existing ISS.
>
I was just using that as an example, not necessarily the BEST or
most likely example.

I agree with your analysis of the real costs of earth's energy
sources, but that analysis will not be adopted by any policy makers.

You know, the killer application may turn out to be militarization.
Not that I'm advocating it, but they have huge budgets, and if the
arms race or defensive positions develop in space, then an
infrastructure apart from NASA/scientific, develops, crew, experts,
followed by civilian support, followed by families, followed by
commerce.

It's a guessing game as to how the ladder will unfold. If energy
costs go through the roof because the greenhouse effect becomes so
severe that taxes are used to inhibit energy consumption, then SPS
has a good shot.

> > > >
> > > >
> > > > > solution I foresee is that downrange of the
> mass
> > > > driver is a
> > > > > particle beam cannon which applies the
> correct
> > > > amount of energy to
> > > > > the "in-flight" payload to alter its course.
> > > This
> > > > seems problematic,
> > > >
> > >
> > > I am not sure how that would work.
> > >

I'm not either. Vaporware. I was thinking it would work by having
the particle/energy beam vaporize some of the payload that was
arriving and these forces would work to slow down the velocity, or
change the orbit of the payload. Having a number of these beams
working on a payload and you could really fine tune its path and
velocity.

>
> Again, I am not sure how such a system wolod work.
>
> It might be most practical to attach a thruster or a
> mini-tug to every payload launched by the mass driver.
> This would permit in-course corrections.
>
> Note that launching from non-ideal orbital positions
> would not only result in higher launching velocity
> requirement, it would also result in hgiher braking
> velocity reequirement at the desitination.

Yes. Very good point.