>
> Message: 4
> Date: Thu, 19 Dec 2002 12:01:58 -0500
>
> Well, that's quite a demo. If funds were available for it, then yes, it
> could really open the lunar frontier in a major way.
>
> But frankly, I'd settle for something much, much less in the near-term. If
> there were a small but growing research base at Malapert Mountain that
> "lived off the land" in the sense of providing its own radiation
> shielding, its own oxygen for refueling of descent/ascent craft, and
> providing for a few other mass-intensive needs with local resources, then
> I'd be a happy camper. If small robotic factories for producing
> low-grade solar cells arrived at Malapert Mountain 5 years before the
> first human, that'd be o'k with me too.
>
> Dream big or dream small. I guess I'm dreaming small.
>
> Ron
> ******
Ron the ability to raise funding correlates more to the ROI, than to the amount of money requested, it also correlates to the
intagible "giggle factor".
$ 10 billion with an ROI of 100:1 would be easier to raise than $1 billion with no ROI.
What is the ROI for bootstrapping ?
>
> Message: 5
> Date: Thu, 19 Dec 2002 12:44:03 -0500
>
> Smaller transmitter and receiver sizes are practical with higher
> microwave transmission frequencies, although that requires higher
> quality antennas also. The typical frequency Charles is probably
> assuming is 2.5 GHz, but there's nothing particularly special about that
> number, other than FCC regulations and atmospheric considerations,
> neither of which apply to the Moon. At 250 GHz, the two would need to be
> only 1/10 the diameter (see
> http://www.spacefuture.com/archive/a_few_things_you_occasionally_wanted_to_know_about_wireless_power_transmission.shtml
> for example).
>
> Also, the transmitting antenna does not need to be a single continuous
> object of several hundred meters or kilometers across - rather several
> transmitting antennas can work together in "phased array mode" to
> produce a single main beam lobe at the receiving location.
>
> In other words, I believe the demo could be quite a bit smaller than
> Charles suggests.
>
> Arthur
>
Good points Arthur, I had not really thought about that.
Yes, since the Moon has no atmosphere, optimization criteria becoem different. We would want to minimize the size of the
transmit antenna and rectenna, so we would want to use the highest frequencies where the DC to RF and RF to DC efficiencies are
still up in the 90's %. At some point as the frequencies transition from Microwave to Infrared, the conversion efficiency
starts to drop off rapidly.
Lasers are not much use, because the rectenna would simply be PV arrays are low conversion efficiency.
I wonder what would be the highest useful frequency. Anybody know ?
I don't know much about the electrical engineering side of this, but
these guys:
seem to have RF/microwave stuff going up into the 100's of GHz, so
there's at least some
equipment available. It might be one of those things where "more
research is needed"
to get equipment with the right characteristics for this...
Arthur
Charles: Do you anticipate that the L1 SPS demo would have an ROI of
100:1 ? What kinds of cash flows do you imagine would accrue from such
a demo?
charles radley c.radley@...
12/20/02 09:31 AM
>
> Message: 4
> Date: Thu, 19 Dec 2002 12:01:58 -0500
>
> Well, that's quite a demo. If funds were available for it, then yes,
it
> could really open the lunar frontier in a major way.
>
> But frankly, I'd settle for something much, much less in the near-term.
If
> there were a small but growing research base at Malapert Mountain that
> "lived off the land" in the sense of providing its own radiation
> shielding, its own oxygen for refueling of descent/ascent craft, and
> providing for a few other mass-intensive needs with local resources,
then
> I'd be a happy camper. If small robotic factories for producing
> low-grade solar cells arrived at Malapert Mountain 5 years before the
> first human, that'd be o'k with me too.
>
> Dream big or dream small. I guess I'm dreaming small.
>
> Ron
> ******
> _________
Ron the ability to raise funding correlates more to the ROI, than to the
amount of money requested, it also correlates to the
intagible "giggle factor".
$ 10 billion with an ROI of 100:1 would be easier to raise than $1 billion
with no ROI.
What is the ROI for bootstrapping ?
>
> Message: 5
> Date: Thu, 19 Dec 2002 12:44:03 -0500
>
> Smaller transmitter and receiver sizes are practical with higher
> microwave transmission frequencies, although that requires higher
> quality antennas also. The typical frequency Charles is probably
> assuming is 2.5 GHz, but there's nothing particularly special about that
> number, other than FCC regulations and atmospheric considerations,
> neither of which apply to the Moon. At 250 GHz, the two would need to be
> only 1/10 the diameter (see
> http://www.spacefuture.com/archive/a_few_things_you_occasionally_wanted_to_know_about_wireless_power_transmission.shtml
> for example).
>
> Also, the transmitting antenna does not need to be a single continuous
> object of several hundred meters or kilometers across - rather several
> transmitting antennas can work together in "phased array mode" to
> produce a single main beam lobe at the receiving location.
>
> In other words, I believe the demo could be quite a bit smaller than
> Charles suggests.
>
> Arthur
>
Good points Arthur, I had not really thought about that.
Yes, since the Moon has no atmosphere, optimization criteria becoem
different. We would want to minimize the size of the
transmit antenna and rectenna, so we would want to use the highest
frequencies where the DC to RF and RF to DC efficiencies are
still up in the 90's %. At some point as the frequencies transition
from Microwave to Infrared, the conversion efficiency
starts to drop off rapidly.
Lasers are not much use, because the rectenna would simply be PV arrays
are low conversion efficiency.
I wonder what would be the highest useful frequency. Anybody know ?
>Lasers are not much use, because the rectenna would simply be PV arrays are low conversion efficiency.
>
Do you have a reference for that low conversion efficiency? The best PVs
are now at about 30% when used with sunlight, but that aside, all PVs
are very efficient at their favourite frequencies- pretty much the
frequencies corresponding to those emitted by infrared lasers. I don't
have the figures to hand, but I would not be surprised if they weren't
50-70% efficient, even the cheapest ones.
handle most of the frequencies well at all; that's why they're usually
down at 10-15% efficient.
--- In ssi_list@... Ian Woollard
>
> >Lasers are not much use, because the rectenna would simply be PV
arrays are low conversion efficiency.
> >
> Do you have a reference for that low conversion efficiency? The
best PVs
> are now at about 30% when used with sunlight,
the most efficient PV available because if they have to be
constructed from orbital resources, I wonder if we'll be able to
acquire the Group III or V periodic table elements to alloy with
gallium arsenide, indium, copper indium diselenide, gallium indium
phosphide, and germanium.
I think it more likely that a simpler silicon PV cell will be used
because it will be more easily manufactured from lunar silicon using
the Czochralski or float zone method in a zero-g or lunar
environment.
I think that there is a chance that PV technology and solar
thermal/sterling engine may not even be used. With the abundance of
ilmenite in the lunar regolith, after we extract the iron and an
oxygen atom we'll be left with titanium dioxide, which when
impregnated with a dye can replace the semiconducting material used
in PV cells to create a voltage. This may be a cheaper technology to
implement than large scale crystal growth in orbital or lunar
facilities.
TangoMan
> Charles: Do you anticipate that the L1 SPS demo would have an
ROI of
> 100:1 ? What kinds of cash flows do you imagine would accrue
from such
> a demo?
>
> Ron
> *******
Here are some facts to work with.
The capital cost of power plants tends to the dollar/watt range for
plants in the 100MW to 2GW range.
Fuel costs are extra. I'm sorry I can't provide the data on the fuel
cost component of operational expenses but I've lost my data. If
you're really interested it shouldn't be too hard to find out how
much energy is released from oil, natural gas, coal.
We know that the wholesale cost of electricity is in the range of 2-
4 cents per kW/hr.
So if you have a modest SPS of 1GW, it could produce a revenue
stream of $175.2 - $350.4 million dollars per year.
Using O'Neill's figures for the mass of a SPS, 10 kg per kW, the 1
GW SPS would mass at 10,000 tonnes.
Granted these are all disparate facts, but my analysis is that the
capital cost could exceed the earth-based plants because the fuel
cost would be non-existent, so I'll double the capital cost
allowance. Subtracting from this capital cost is the lease for the
rectenna land (5 mile radius), which shooting from the hip, we
should be able to find a dual use lease rate of $1,000/acre per
year, which at $50,200,000 per year translates to a cost of
$0.0057/kW/hr.
So, two factors become clear at this stage. 1.) The capital cost of
a 1 GW SPS should be be no more than 2 billion dollars. 2.)
O'Neill's figures indicate that the mass should be 10,000 tonnes but
it's difficult for me to determine the mass breakdown between PC
cells, transmitter/klystron, support structure, or alternative to PV
a solar thermal system, so I'm just going to assume the material
cost to be the same as on Earth, $1/kW and the other dollar will be
for our orbital infrastructure. More appropriately for our pilot
plant project, let's assume that the 10,000 tonnes is lifted from
earth at a cost of $500/kg, for a total lift cost of $5 billion, on
top of the plant cost of $1 billion. So, the pilot SPS is 6 times
more expensive than an Earth alternative with no allowance made for
orbital construction costs.
I don't have the time to do a sophisticated financial analysis,
though you do raise an interesting topic. But if we do a simple
discounted cash flow analysis assuming an infinite series cash flow
of $300 million/year ($0.04 kW/hr) at a high risk cost of capital of
35%, then the 1 GW SPS should cost no more than $857 million.
Clearly the SPS demonstrator will be a losing investment.
But as a pilot project it doesn't have to be judged by investment
standards. If the technology works out, then the risk to the capital
will diminish and if long term bonds are issued (personally I'd like
to see 100 year bonds come back to the market in a significant
fashion - think about how little deprection there would be of
orbital assets,) then we may be safe to assume a capital cost of 9%,
resulting in a maximum SPS cost of $3.33 billion dollars. Now we're
in the game. VERY SIMPLISTIC ANALYSIS FOLLOWS: For each SPS we have
$2.33 billion to offset the cost of the orbital infrastructre. Or
put another way, every 10 GW SPS could be competitively priced at
$20 billion, the SPS operator would earn a profit identical to their
Earth based competitors, the future cash flow could be sold and the
remaining $13.33 billion could be invested in orbital infrastructure
to earn, or lose, whatever return can be extracted from other
ventures.
Further, if we assume an aggressive posture in terms of capturing
market share by pushing for environmental penalties for pollutors,
and by lowering our wholesale rate at a steady 1% real dollar cost
per year, then our SPS can cost no more than $2.97 billion but will
create greater demand for more SPS units.
Of course this whole analysis is built on a house of cards series of
assumptions which I can't support and was done very quickly, but
whatever numbers you choose for your own analysis, what is clear is
that the amortization of the orbital industrialization structure
must be borne by many SPSs. Then we're looking at a profitable
industry. A few SPS can't support the mining, refining, fabrication,
fuel extraction, farming, housing, etc that we'll need in orbit.
Hope this helps.
TangoMan
> Charles: Do you anticipate that the L1 SPS demo would have an
ROI of
> 100:1 ? What kinds of cash flows do you imagine would accrue
from such
> a demo?
>
> Ron
> *******
Here are some facts to work with.
The capital cost of power plants tends to the dollar/watt range for
plants in the 100MW to 2GW range.
Fuel costs are extra. I'm sorry I can't provide the data on the fuel
cost component of operational expenses but I've lost my data. If
you're really interested it shouldn't be too hard to find out how
much energy is released from oil, natural gas, coal.
We know that the wholesale cost of electricity is in the range of 2-
4 cents per kW/hr.
So if you have a modest SPS of 1GW, it could produce a revenue
stream of $175.2 - $350.4 million dollars per year.
Using O'Neill's figures for the mass of a SPS, 10 kg per kW, the 1
GW SPS would mass at 10,000 tonnes.
Granted these are all disparate facts, but my analysis is that the
capital cost could exceed the earth-based plants because the fuel
cost would be non-existent, so I'll double the capital cost
allowance. Subtracting from this capital cost is the lease for the
rectenna land (5 mile radius), which shooting from the hip, we
should be able to find a dual use lease rate of $1,000/acre per
year, which at $50,200,000 per year translates to a cost of
$0.0057/kW/hr.
So, two factors become clear at this stage. 1.) The capital cost of
a 1 GW SPS should be be no more than 2 billion dollars. 2.)
O'Neill's figures indicate that the mass should be 10,000 tonnes but
it's difficult for me to determine the mass breakdown between PC
cells, transmitter/klystron, support structure, or alternative to PV
a solar thermal system, so I'm just going to assume the material
cost to be the same as on Earth, $1/kW and the other dollar will be
for our orbital infrastructure. More appropriately for our pilot
plant project, let's assume that the 10,000 tonnes is lifted from
earth at a cost of $500/kg, for a total lift cost of $5 billion, on
top of the plant cost of $1 billion. So, the pilot SPS is 6 times
more expensive than an Earth alternative with no allowance made for
orbital construction costs.
I don't have the time to do a sophisticated financial analysis,
though you do raise an interesting topic. But if we do a simple
discounted cash flow analysis assuming an infinite series cash flow
of $300 million/year ($0.04 kW/hr) at a high risk cost of capital of
35%, then the 1 GW SPS should cost no more than $857 million.
Clearly the SPS demonstrator will be a losing investment.
But as a pilot project it doesn't have to be judged by investment
standards. If the technology works out, then the risk to the capital
will diminish and if long term bonds are issued (personally I'd like
to see 100 year bonds come back to the market in a significant
fashion - think about how little deprection there would be of
orbital assets,) then we may be safe to assume a capital cost of 9%,
resulting in a maximum SPS cost of $3.33 billion dollars. Now we're
in the game. VERY SIMPLISTIC ANALYSIS FOLLOWS: For each SPS we have
$2.33 billion to offset the cost of the orbital infrastructre. Or
put another way, every 10 GW SPS could be competitively priced at
$20 billion, the SPS operator would earn a profit identical to their
Earth based competitors, the future cash flow could be sold and the
remaining $13.33 billion could be invested in orbital infrastructure
to earn, or lose, whatever return can be extracted from other
ventures.
Further, if we assume an aggressive posture in terms of capturing
market share by pushing for environmental penalties for pollutors,
and by lowering our wholesale rate at a steady 1% real dollar cost
per year, then our SPS can cost no more than $2.97 billion but will
create greater demand for more SPS units.
Of course this whole analysis is built on a house of cards series of
assumptions which I can't support and was done very quickly, but
whatever numbers you choose for your own analysis, what is clear is
that the amortization of the orbital industrialization structure
must be borne by many SPSs. Then we're looking at a profitable
industry. A few SPS can't support the mining, refining, fabrication,
fuel extraction, farming, housing, etc that we'll need in orbit.
Hope this helps.
TangoMan
You're not getting me; I'm saying for laser power beaming between L1 and the lunar surface for example, the worst PV you can find can give you 50% efficiency, under a dollar per watt or so, including the laser and PV. And you can use direct sunlight when it's available as well.
I see what you mean about laser beaming. Yes, it definitely makes
mroe sense. I'm with you
do you think that Dubya would be happy with a multi-gigawatt
concentrated laser in orbit.
Wouldn't that be considered a WMD because of its energy density?
Just a thought.
TangoMan
--- In ssi_list@... Ian Woollard
> You're not getting me; I'm saying for laser power beaming between
L1 and
> the lunar surface for example, the worst PV you can find can give
you
> 50% efficiency, under a dollar per watt or so, including the laser
and
> PV. And you can use direct sunlight when it's available as well.
>
> Microwave is great for returning power to earth, because it
punches
> through the clouds, but there's no weather on the moon, and so
it's
> going to be more expensive by the time you've laid out multiple
square
> kilometers of rectenna. I mean, microwaves don't focus down worth
a
> damn from any distance unless you have huge antenna at each end.
Light
> is easy.
>
> >--- In ssi_list@... Ian Woollard
> >
> >>
> >>
> >>
> >>>Lasers are not much use, because the rectenna would simply be
PV
> >>>
> >>>
> >arrays are low conversion efficiency.
> >
> >>>
> >>>
> >>>
> >>>
> >>Do you have a reference for that low conversion efficiency? The
> >>
> >>
> >best PVs
> >
> >>are now at about 30% when used with sunlight,
> >>
> >>
> >
> >True enough, but I'm not ready to accept that a SPS will be using
> >the most efficient PV available because if they have to be
> >constructed from orbital resources, I wonder if we'll be able to
> >acquire the Group III or V periodic table elements to alloy with
> >gallium arsenide, indium, copper indium diselenide, gallium
indium
> >phosphide, and germanium.
> >
> >I think it more likely that a simpler silicon PV cell will be
used
> >because it will be more easily manufactured from lunar silicon
using
> >the Czochralski or float zone method in a zero-g or lunar
> >environment.
> >
> >I think that there is a chance that PV technology and solar
> >thermal/sterling engine may not even be used. With the abundance
of
> >ilmenite in the lunar regolith, after we extract the iron and an
> >oxygen atom we'll be left with titanium dioxide, which when
> >impregnated with a dye can replace the semiconducting material
used
> >in PV cells to create a voltage. This may be a cheaper technology
to
I will debate your numbers later, the particular
values do not matter for my argument..
will repeat it.
We can calculate an ROI for SPS. It is large. I
threw out 100:1 for no particular reason. It could
be a lot larger, I am referring to the size of the
world's energy market, not the ROI of a single SPS at
L-1. The demo at L-1 by itself will not make a
profit. But the huge industry it will spawn is the
ROI.
What is the ROI for the boostrapping model ? I submit
that it is zero, anybody care to defend a different
number ?
>
> I will debate your numbers later, the particular
> values do not matter for my argument..
substantiation, but the magnitude of scale that they refer to is
important. One pilot project will not earn a return sufficient to
amortize the broad infrastructure required to bring about the High
Frontier.
>
> Ron and yourself have dodged my central issue, so I
> will repeat it.
>
> We can calculate an ROI for SPS. It is large. I
> threw out 100:1 for no particular reason. It could
> be a lot larger, I am referring to the size of the
> world's energy market, not the ROI of a single SPS at
> L-1. The demo at L-1 by itself will not make a
> profit. But the huge industry it will spawn is the
> ROI.
I don't disagree with your proposition that a successful
demonstrator of the technology will indeed lower the barriers for
the next iterations of SPS, but the success of that endeavor
shouldn't be defined as a return on investment, which is a specific
financial definition.
I jumped into the debate because I felt I had an opinion I could
offer on the ROI issue that was raised.
Philosophically, I walk the road of compromise between your two
positions as I detailed in my 60 Easy steps post. I actually favor
both positions but at very distinct stages of orbital development,
do favor lunar development, don't favor the South Pole, and see
Ron's small lunar development as a necessary precursor to the first
L1 demonstrator project.
(as an aside, I know that my 60 Easy Steps post was long, but didn't
anybody (other than Charles) have ANYTHING to say about it or the
order of the steps. Geez I spent like a half a day writing that
novel in the hopes that others could offer their insights into
refining the critical path necessary for developing the High
Frontier.) Is there no interest in this type of minutae with regards
to the planning?
>
> What is the ROI for the boostrapping model ?
The answer to this question is dependent on one's definition of the
term "bootstrapping."
My understanding of ther term is that that the bootstrapping model
is dependent on each preceding step being profitable enough to
either fund the following step. A broader interpretation might
include removing enough uncertainty to warrant further investment
into the next step with the likely promise of future financial
rewards.
To use ROI as a criteria would restrict us to consider only the
first definition of the model, so the implication is that an ongoing
bootstrapping model must have a positive ROI.
No financier will embark on a project with returns forecasted 30 -
50 years in the future. The profit window must be on a near horizon,
but not necessarily an immediate horizon.
Other criteria should be used for the second definition of the model.
>I submit that it is zero, anybody care to defend a different
> number ?
I'll defend the position that it must be some value greater than
zero if the bootstrapping model, being dependent on the ROI
criterion, is to proceed to its next step.
OTH, if the criteria for success is to be a factor other than ROI,
then ROI can indeed be zero and the model can still proceed onwards.
I know, it may be nitpicking, but we should all understand the
common definitions of our favorite discussion topic :) If we're in
agreement on the definition and you feel that we're still
disagreeing as to the issues I'm more than happy to engage in a
dialogue with you or Ron, or to read your rebuttal to each other's
positions. Thus far the dialogue between you has been interesting.
TangoMan
I see what you mean about laser beaming. Yes, it definitely makes mroe sense. I'm with you except . . . do you think that Dubya would be happy with a multi-gigawatt concentrated laser in orbit. Wouldn't that be considered a WMD because of its energy density? Depends on how it is constructed. If it is kept down to 1kw/m^2 then its no death ray. Provided the lenses are small enough, it's physically impossible to get the light too concentrated.
Just a thought. TangoMan --- In ssi_list@... Ian Woollard wrote: You're not getting me; I'm saying for laser power beaming between L1 and the lunar surface for example, the worst PV you can find can give you 50% efficiency, under a dollar per watt or so, including the laser and PV. And you can use direct sunlight when it's available as well. Microwave is great for returning power to earth, because it punches through the clouds, but there's no weather on the moon, and so it's going to be more expensive by the time you've laid out multiple square kilometers of rectenna. I mean, microwaves don't focus down worth a damn from any distance unless you have huge antenna at each end. Light is easy.
--- In ssi_list@... Ian Woollard
>
> >I see what you mean about laser beaming. Yes, it definitely makes
> >mroe sense. I'm with you
> >
> >except . . .
> >
> >do you think that Dubya would be happy with a multi-gigawatt
> >concentrated laser in orbit.
> >
> >Wouldn't that be considered a WMD because of its energy density?
> >
> Depends on how it is constructed. If it is kept down to 1kw/m^2
then its
> no death ray. Provided the lenses are small enough, it's
physically
> impossible to get the light too concentrated.
>
1,000 watts/m^2 compared to the 1,360 watts/m^2 of sunlight,
comparing efficiencies of 70% and 20%, respectively, then the laser
would be 157% more efficient than solar PV.
So here's what I don't get: you still need PVs on the lunar surface
to convert the laser light, albeit at a higher efficiency but now
you need a large laser, power source and radiator in orbit, or at
L1. Is this less expensive or complex? I don't know.
Also, a laser that can focus a beam for 30,000 miles is considered
dangerous, isn't it? Also, the laser will be producing a prodigious
amount of energy but focusing it across a large area to achieve a
weak energy density, but how difficult would it be to change the
optics and increase the energy density on short notice?
If your answer to the above points is that they are indeed valid
concerns about weaponization, then is there really a need to keep
the energy density down to 1,000 m^2? If the concerns are satified,
then why not pump it up to 10-20,000 watts/m^2?
TangoMan
--- "victoriatangoman tango_dancer@...
> --- In ssi_list@... Ian Woollard
> > Depends on how it is constructed. If it is kept
> down to 1kw/m^2
> then its
> > no death ray. Provided the lenses are small
> enough, it's
> physically
> > impossible to get the light too concentrated.
> >
they will ever be approved for beaming towards Earth.
Take a look at the US Code of the Federal Regulations
(I forget the CFR number but I can research it) which
govern how much free laser energy is allowed for
public exposure (administered by the FDA).
It is tiny compared to the allowable microwave levels.
>
> OK, I'm missing something here. If we keep the
> energy density to
> 1,000 watts/m^2 compared to the 1,360 watts/m^2 of
> sunlight,
> comparing efficiencies of 70% and 20%, respectively,
> then the laser
> would be 157% more efficient than solar PV.
>
On thing here makes a difference. The sun angle
across the PV arrays on the lunar surface constantly
changes, and is usually lkess than the 1,360 w/m^2.
To maintian constant max power the PV array must have
expensive and heavy steering equipment.
Whereas a rectenna does not need to be steered, and
always gets maximum power.
> So here's what I don't get: you still need PVs on
> the lunar surface
> to convert the laser light, albeit at a higher
> efficiency but now
> you need a large laser, power source and radiator in
> orbit, or at
> L1. Is this less expensive or complex? I don't know.
>
It is basically the same as a microwave SPS, except
that a laser is used instead of a maser. The size of
the radiaiton depends on the amount of waste heat.
Not sure about that, is a laser as efficient as a
klystron ? The advantage is that the transmitting
"antenna" (a reflector mirror probably) is a lot
smaller.
> Also, a laser that can focus a beam for 30,000 miles
> is considered
> dangerous, isn't it? Also, the laser will be
Yes, getting FDA approval for a big laser for pointing
top Earth will be a major challenge. There are very
strict laws on the books governing exposure of workers
and the public to stray laser light.
Even getting a 1 Watt laser approved involves a lot of
paperwork and testing, especially if it is infra-red
(invisible).
> producing a prodigious
> amount of energy but focusing it across a large area
> to achieve a
> weak energy density, but how difficult would it be
> to change the
> optics and increase the energy density on short
> notice?
>
Making the beam narrow requires increasing the size of
the transmitting reflector. But it would be a net
cost saving, because we want to make the rectenna as
small and lightweight as possible.
We are probably limited by human safety limits.
However, on the Moon (as opposed to Earth) there is no
local population, everybody will be employees of the
development organization, so they can be controlled by
contract to stay away from the rectenna when in use.
There can be security procedures to make sure nobody
goes near the rectenna by accident.
Maybe that will allow us to operate at a higher power
level than we would on Earth.
> If your answer to the above points is that they are
> indeed valid
> concerns about weaponization, then is there really a
> need to keep
> the energy density down to 1,000 m^2? If the
> concerns are satified,
> then why not pump it up to 10-20,000 watts/m^2?
>
Reducing the beam size means increasing the size of
the transmitting antenna / reflector.
This is known as the Raleigh diffraction effect.
But there is a positive ROI, making things on the
Moon small (e.g. rectenna) at the cost if increasing
things at L-1 is a good trade off.
Tangoman, I much admire the passion that drives you to extensively write about
your ideas - you're by far one of the main posters of this list, and one of
the greater seeders of rich discussions.
or both, to read posts *that* extensive. I am afraid to say that I'm one of
them :-(. Perhaps if you try to break your 60 Easy Steps in separate posts
sent spaced by some period of time - say, one Step per day - you would
captivate a much larger public and stimulate much more discussion on the
issues...
That's just a hint - I am no one to tell others how to write, or how to read.
Lucio Coelho
--- In ssi_list@... Ian Woollard wrote: victoriatangoman wrote: I see what you mean about laser beaming. Yes, it definitely makes mroe sense. I'm with you except . . . do you think that Dubya would be happy with a multi-gigawatt concentrated laser in orbit. Wouldn't that be considered a WMD because of its energy density? Depends on how it is constructed. If it is kept down to 1kw/m^2 then its no death ray. Provided the lenses are small enough, it's physically impossible to get the light too concentrated. OK, I'm missing something here. If we keep the energy density to 1,000 watts/m^2 compared to the 1,360 watts/m^2 of sunlight, comparing efficiencies of 70% and 20%, respectively, then the laser would be 157% more efficient than solar PV. So here's what I don't get: you still need PVs on the lunar surface to convert the laser light, albeit at a higher efficiency but now you need a large laser, power source and radiator in orbit, or at L1. Is this less expensive or complex? I don't know. No. It's just an array of LEDs or laser diodes. They're really cheap; under a dollar a watt; and really low mass.
Also, a laser that can focus a beam for 30,000 miles is considered dangerous, isn't it? No. Whether a beam of light is dangerous or not depends on the power density.
Also, the laser will be producing a prodigious amount of energy but focusing it across a large area to achieve a weak energy density, but how difficult would it be to change the optics and increase the energy density on short notice? Pretty difficult; large mirrors are expensive and difficult to make. It's like making a telescope twice the diameter, the costs mount rapidly. Upping the energy requires installing bigger solar panels, which would be very obvious, and you'd still have to install more LEDs or laser diodes, and reallign everything; it's slow difficult work.
If your answer to the above points is that they are indeed valid concerns about weaponization, then is there really a need to keep the energy density down to 1,000 m^2? If the concerns are satified, then why not pump it up to 10-20,000 watts/m^2? Well, the PVs start to fry at some point, and keeping the power down prevents it from becoming a death ray accidentally or on purpose (20 kw/m^2 is probably a death ray). The whole point is to build something that isn't a death ray, not build something that is.
--- In ssi_list@... Lucio de Souza Coelho
> Tangoman, I much admire the passion that drives you to extensively
write about
> your ideas - you're by far one of the main posters of this list,
and one of
> the greater seeders of rich discussions.
>
> But unfortunately many people are too lazy, or have too little
available time,
> or both, to read posts *that* extensive. I am afraid to say that
I'm one of
> them :-(. Perhaps if you try to break your 60 Easy Steps in
separate posts
> sent spaced by some period of time - say, one Step per day - you
would
> captivate a much larger public and stimulate much more discussion
on the
> issues...
>
> That's just a hint - I am no one to tell others how to write, or
how to read.
>
> Lucio Coelho
>
heart and break that post up in 60 pieces. :)
I think we can all see the end results of our vision for the High
Frontier, but I am very interested in the road that we must travel
to get there. There are so many forks in that road and so many
options that we can utilize that I'm very curious how a group of us
High Frontier types could put our minds together through this
discussion list and actually optimize a BEST path to the High
Frontier.
So, what follows for the next two months is a daily missive on the
steps to bootstrapping that will serve as a basis for critique and
improvement. (I reserve the right to edit from the original message.)
TangoMan
how about two steps per day...2 months is a long time.
steps to bootstrapping that will serve as a basis for critique and
improvement. (I reserve the right to edit from the original message.)
> how about two steps per day...2 months is a long time.
not very detailed, so perhaps I can flesh them out.
Even with 2 a day, we'll still all be free to read and comment on
all of the posts rather than having to pick and choose where we'll
make our comments. Hopefully some of these threads will stay alive
for more than a day.
There is one problem with the daily approach though. Many of the
steps lay the groundwork for future steps but this may not be
evident when you read the step in isolation. I have a feeling I'll
be responding with a lot of " . . but you have to see the whole
picture" :) type of comments.
Anyways, I'll primarily be be snipping each step from that long post
and be fleshing it out with some new comments, so those who are
curious can always read ahead to form their critiques, suggestions
and alternatives.
TangoMan
> (as an aside, I know that my 60 Easy Steps post was long, but
> didn't anybody (other than Charles) have ANYTHING to say about it
> or the order of the steps.
on one little part...
> Geez I spent like a half a day writing that novel in the hopes
> that others could offer their insights into refining the critical
> path necessary for developing the High Frontier.) Is there no
> interest in this type of minutae with regards to the planning?
I'm interested. And now that you are going to be doing the two-
steps-a-day thing, I'll see if I can say a bit more about more of
the steps. Not promising that I'll have something to say about
*every one*, but we'll see. Again, I rather liked your long post.
Xenophile (who even mentioned the 60 Easy Steps to some family as we
gather for the holidays... though my nephew will only be interested
if I point out that there will be girls in space)
Charles:
"I am referring to the size of the
world's energy market, not the ROI of a single SPS at
L-1. The demo at L-1 by itself will not make a
profit. But the huge industry it will spawn is the
ROI."
As for bootstrapping, I think it is certainly possible that bootstrapping
could lead to the same sort of SPSs and industry downstream as your L1
demo might. By 'bootstrapping' in this context, I mean something, for
instance, like the following:
1.) Send teleoperated/robotic equipment to Malapert Mountain to begin to
make solar cells using local materials.
2.) After a few years of (1), send a liquid oxygen plant to Malapert
Mountain and start making liquid oxygen using teleoperation.
3.) After (1) has reached a specified level of megawatts and after (2)
there is enough liquid oxygen for refueling, then establish a small human
base at Malapert Mountain. The base will have all the electricity and
liquid oxygen it needs as a result of steps (1) and (2).
4.) After some years of (3), develop components of mass driver at or near
Malapert Mountain and transport them to the equator using some means
(small-hop rocket, or maybe even surface transport).
5.) Build equatorial mass driver, and move on to O'Neill nirvana, complete
with SPSs and happiness for all.
For (1), I was definitely thinking small is better. Perhaps (1) is
something that could come in under the NASA budgetary radar screen and be
treated more or less like an expensive deep space probe. For (1), I'd
envision using current launchers and miniaturizing as much as possible.
My thoughts were, "How can we actually get started with minimal up-front
expenditure?" Step (1) is the bootstrapping step that I'd hope to do
with as small an upfront expenditure as possible.
But if you can secure the larger hunk of upfront cash required for your L1
SPS demo, then more power to you.
My thesis is that the larger up-front expenditures might result in the
idea being shot down in Congress or by the Administration.
And no, I don't expect that private industry would fund either your L1
demo or my alternative bootstrapping scenario. Alas.
As for the relative 'ROI' of these alternatives, I have no clue.
Ron
charles radley cfrjlr@...
12/20/02 11:12 PM
I will debate your numbers later, the particular
values do not matter for my argument..
Ron and yourself have dodged my central issue, so I
will repeat it.
We can calculate an ROI for SPS. It is large. I
threw out 100:1 for no particular reason. It could
be a lot larger, I am referring to the size of the
world's energy market, not the ROI of a single SPS at
L-1. The demo at L-1 by itself will not make a
profit. But the huge industry it will spawn is the
ROI.
What is the ROI for the boostrapping model ? I submit
that it is zero, anybody care to defend a different
number ?
RE: "Microwave is great for returning power to earth, because it punches through the clouds, but there's no weather on the moon, and so it's going to be more expensive by the time you've laid out multiple square kilometers of rectenna. I mean, microwaves don't focus down worth a damn from any distance unless you have huge antenna at each end. Light is easy."
I do not agree with the above. It used to be true, but not any more. Antenna theory works equally well for transmitters and receivers. I don't have the reference, but radio antenna in the US south west have recently imaged stellar objects with a resolution of afew micro-arc-seconds. With out adaptive optics, perhaps 0.7 arc seconds (i.e. nearly a million times larger (where larger is worse)) is the best one can do with visible light. With continued development, one might predict that soon microwaves will be resolved (now think aimed) a million times more accurately. Microwave generators can be individually controlled in amplitude and phase, so a solar power satellite, Moon base or redirecting could accurately control the direction and size of their beams. This field, using microwaves, which includes radio astronomy, is advancing rapidly. Sincerely, Jay Huebner
RE: "Microwave is great for returning power to earth, because it punches through the clouds, but there's no weather on the moon, and so it's going to be more expensive by the time you've laid out multiple square kilometers of rectenna. I mean, microwaves don't focus down worth a damn from any distance unless you have huge antenna at each end. Light is easy."
I do not agree with the above. It used to be true, but not any more. Antenna theory works equally well for transmitters and receivers. I don't have the reference, but radio antenna in the US south west have recently imaged stellar objects with a resolution of afew micro-arc-seconds. Actually, I studied this at university. Sadly, this trick doesn't help.
With synthetic aperture you have two or more antenna as widely spaced as possible and combine the signals to get better resolution; in effect you have a huge antenna, kind of. But the kicker is that the total power you get this way is only as much as the sum of the dish size.
But with microwave power transmission the total power is what you want; and trust me on this, the maths says you need square kilometers of antenna from geosynchronous orbit to the earths surface and comparable or larger sizes between L1 and the lunar surface.
With out adaptive optics, perhaps 0.7 arc seconds (i.e. nearly a million times larger (where larger is worse)) is the best one can do with visible light. Adaptive optics is used to help remove the atmospheric effects (e.g. "twinkle, twinkle little star"); as I say this affects microwaves much less, which is another reason why the researchers were able to get such good results.
With continued development, one might predict that soon microwaves will be resolved (now think aimed) a million times more accurately. Sorry no. This is forbidden by Physics (Maxwells equations). There have been no breakthroughs since O'Neills day in this area; what O'Neill said about microwave power transmission cannot be beaten with todays technology or physics using microwaves. There's no theoretical way to do this today, atleast not with reasonable efficiencies; although synthetic aperture could work if you're prepared to slop most of your power across the moon in an interference pattern, but then your destination point wouldn't get the power you launched.
By way of contrast visible light is a millions times higher frequency than microwaves and thus can be aimed a millions times more narrowly (once you get above the atmosphere).
Sincerely, Jay Huebner
> With synthetic aperture you have two or more antenna as widely spaced as
> possible and combine the signals to get better resolution; in effect you
> have a huge antenna, kind of. But the kicker is that the total power you
> get this way is only as much as the sum of the dish size.
>
> But with microwave power transmission the total power is what you want;
> and trust me on this, the maths says you need square kilometers of
> antenna from geosynchronous orbit to the earths surface and comparable
> or larger sizes between L1 and the lunar surface.
>
transmitting end - you just send your power out through whatever surface
area you have, no problem. The issue is concentrating the microwave
power into a central transmitted lobe - which can be done well enough
with enough transmitting antennas (dependency is on number of antennas
and total area covered by their locations, not total antenna surface area).
The receiving end, however, has to cover the entire central lobe area,
because otherwise you're missing a lot of power, as Ian says.
There is a similar asymmetry between transmitting and receiving
at optical frequencies, with the use of lasers (Jay's original
argument on spread referred to non-laser light sources, I believe) - however,
I don't believe DC to optical energy conversion efficiencies are anywhere
near what you can get with the electrical components used for microwave
transmission.
Arthur