Global wireless hotspot

Ian Parker wrote:

I am not going to reply point by point. I would however like to make a
number of general comments.

1) Smart pebbles is an expression which means lightweight intelligent
spacecraft designed to do a specific job. It does NOT mean that the
spacecraft is dense like a pebble. I am simply using the extression a
boulder for a lower order of division. A number of pebbles may be
linked together for a specific task, for example a high resolution
steered array.

2) Power is simple. Solar power, paddles. We could try the new 80g/m^2
cells.

.....

I like the idea of global wireless, low orbits so that voice doesn't have
the delay. Lasers for plenty of bandwidth, phased arrays, low power,...

I'm kind of surprised that no one has produce solar cells with microcircuits
on the back side of the silicon. There is plenty of space to have old
technology "big" circuits that aren't affected by radiation as much. It's
the perfect place to put the arrays of computers, routers, rf circuits
right on the back of the solar cells. Then cover the microcircuits with a
radiator/antenna. Solar cells pointed at the sun, radiator away from the
sun, most power never leaves the silicon, passed array isn't always pointed
at the earth, but at high noon it is. The microcircuits would be protected
by the solar cell on one side, radiator on the other and would slow die
over time as impacts occur, reducing power and wireless routing
capabilities at the same time. Or, maybe someone is already doing it,
haven't looked on the www yet.

They aren't pebbles, they're flying relay singles.
--
Craig Fink
Courtesy E-Mail Welcome @

On 15 Jan, 14:50, Craig Fink wrote:
Ian Parker wrote:
I am not going to reply point by point. I would however like to make a
number of general comments.

1) Smart pebbles is an expression which means lightweight intelligent
spacecraft designed to do a specific job. It does NOT mean that the
spacecraft is dense like a pebble. I am simply using the extression a
boulder for a lower order of division. A number of pebbles may be
linked together for a specific task, for example a high resolution
steered array.

2) Power is simple. Solar power, paddles. We could try the new 80g/m^2
cells.

....

I like the idea of global wireless, low orbits so that voice doesn't have
the delay. Lasers for plenty of bandwidth, phased arrays, low power,...

Eventually you would probably use MEO. That is when you had such a
number that there would be continual coverage - As with GPS.

The circuits are microwave circuits. The laser circuits was talking
about are hypercubic, that is to say they are for internal
communication between the pebbles. I feel I should say again a
"pebble" is a term for a small intelligent spacecraft. Pebbles have to
behave like a large attenna a kilometer (say) across. The system fails
soft, it gradually degrades if pebbles fail to work. This is an
attractive feature too. It means that we will tolerate a certain level
of failure, we can launch new pebbles to replace those that have
failed.

ONLY A PEBBLE SYSTEM IS CAPABLE OF OPERATING WITHOUT LOSING A BEAT.

Communication computer/space will be using microwaves. The bandwidth
is achieved by spatial separation, by FFT rather than by a single high
bandwidth circuit. That is why you need a large (effective) aperture
anf FFT.

I'm kind of surprised that no one has produce solar cells with microcircuits
on the back side of the silicon. There is plenty of space to have old
technology "big" circuits that aren't affected by radiation as much. It's
the perfect place to put the arrays of computers, routers, rf circuits
right on the back of the solar cells. Then cover the microcircuits with a
radiator/antenna. Solar cells pointed at the sun, radiator away from the
sun, most power never leaves the silicon, passed array isn't always pointed
at the earth, but at high noon it is. The microcircuits would be protected
by the solar cell on one side, radiator on the other and would slow die
over time as impacts occur, reducing power and wireless routing
capabilities at the same time. Or, maybe someone is already doing it,
haven't looked on the www yet.

Good point. For WiFi probably the best solution. For SSP you need an
array producing a Terawatt or so.

They aren't pebbles, they're flying relay singles.

Technical term.

-- Ian Parker

I think I should have made clear that the first systems would be at
GEO as comprehansive coverage would be required for any other choice.
GEO would be the preferred choice for SSP.


- Ian Parker

Ian Parker wrote:
:
:I am not going to reply point by point. I would however like to make a
:number of general comments.
:
:1) Smart pebbles is an expression which means lightweight intelligent
:spacecraft designed to do a specific job. It does NOT mean that the
:spacecraft is dense like a pebble. I am simply using the extression a
:boulder for a lower order of division. A number of pebbles may be
:linked together for a specific task, for example a high resolution
:steered array.
:

The preceding makes no sense (and 'pebble' doesn't really mean what
you describe it as).

:
:2) Power is simple. Solar power, paddles. We could try the new 80g/m^2
:cells.
:

These things are space-rated and have reasonable lifetimes under that
kind of radiation flux?

Cite?

:
:You have raised a number of points about historical systems. Yes it is
:all true. Saturn was the cheapest per Kg. Raising S out of maothballs
:now might not be such a bad idea. However you would have to update the
:electronics.
:

Saturn isn't 'in mothballs'. Saturn is *GONE*. Resurrecting it would
essentially be a clean sheet design, so you might as well just start
with a clean sheet and design to requirements.

:
:Looking at space in general we need to think in terms of high density
:electronics. phsical optics tells us that the Fourier Transform of a
attern of transmitters at infinity represents the angular spread of
:radiation. We have chips which will do an FFT extremely fast. This
:means that our spacecraft will support a large number of circuits
:differing only be geographical position. As I saif we need lasers with
:a hypercube topology as the "butterfly" is essentially a hypercube.
:This is quite feasible. Log(2)N lasters and receivers on each pebble.
:

The preceding makes no sense. Define 'hypercube'.

:
:There is a question about thether WiFi is needed for SSP. To me it is
:clear that it is an intermediate stage, if only bcause the public
:needs to be given assurances that steerable conformally generated
:beams work. You need to demonstate control of a few kilowatts before
:you start transmitting Terawatts. If WiFi works and never drops a beat
:the public just might accept Terawatts.
:

The preceding makes no sense. WiFi is a different frequency with
different beam requirements, different power requirements, different
*EVERYTHING*.

The fact that to you "it is clear that it is an intermediate stage"
cuts no ice, because your ignorance seems to know no bounds.

[Ian spinning off into Artificial Stupidity System (ASS) Chatterbot
mode elided.]


--
"Ordinarily he is insane. But he has lucid moments when he is
only stupid."
-- Heinrich Heine

Ian Parker wrote:
:
:The circuits are microwave circuits. The laser circuits was talking
:about are hypercubic, that is to say they are for internal
:communication between the pebbles.
:

Then you should have said that, because that's not what 'hypercubic'
means.

:
:I feel I should say again a
:"pebble" is a term for a small intelligent spacecraft.
:

Well, no, it isn't. Perhaps in Parkerese, but not in English.

:
:Pebbles have to
:behave like a large attenna a kilometer (say) across. The system fails
:soft, it gradually degrades if pebbles fail to work. This is an
:attractive feature too. It means that we will tolerate a certain level
f failure, we can launch new pebbles to replace those that have
:failed.
:
:ONLY A PEBBLE SYSTEM IS CAPABLE OF OPERATING WITHOUT LOSING A BEAT.
:

So GPS doesn't work?

[Remaining spew elided.]


--
"Ignorance is preferable to error, and he is less remote from the
truth who believes nothing than he who believes what is wrong."
-- Thomas Jefferson

There is a great deal that can be learnt about large conformally
sterred system. I do not deny that a WiFi project would be
challenging. There are, as yet, no space rated products. There are
abundant chips that would work on Earth. There are no reasons to
suppose something could not be built.

Come to think of it there is nothing currently available that would do
a tenth of what some people are suggesting. Space colonies - ha ha.

The Saturn drawings are still BTW available. A Saturn could be
produced from them. BTW - The DOD has a mania for secrecy. How could
anyone hostile produce a Saturn if NASA can't. Why can't the drawings
be sold to anyone round the world?

How is it that people who cannot even do a distillation of H2O2 are
credited with the ability to produce not only WMD but also Saturns.
Never try to figure out the workings of the military mind.

It may or may not be better to start again, but NASA scrapped a system
that worked with one that was twice as expensive. Conspiracy, or
simple incompetance?


- Ian Parker

On Tue, 15 Jan 2008 11:41:35 -0800 (PST), in a place far, far away,
Ian Parker made the phosphor on my monitor glow
in such a way as to indicate that:

There is a great deal that can be learnt about large conformally
sterred system. I do not deny that a WiFi project would be
challenging. There are, as yet, no space rated products. There are
abundant chips that would work on Earth. There are no reasons to
suppose something could not be built.

Come to think of it there is nothing currently available that would do
a tenth of what some people are suggesting. Space colonies - ha ha.

The Saturn drawings are still BTW available. A Saturn could be
produced from them. BTW - The DOD has a mania for secrecy. How could
anyone hostile produce a Saturn if NASA can't. Why can't the drawings
be sold to anyone round the world?

How is it that people who cannot even do a distillation of H2O2 are
credited with the ability to produce not only WMD but also Saturns.
Never try to figure out the workings of the military mind.

It may or may not be better to start again, but NASA scrapped a system
that worked with one that was twice as expensive. Conspiracy, or
simple incompetance?

No, simply typical rambling, babbling lunacy on the part of Ian
Parker.

As I said previously, I know how to build the system of 660 satellites
I described earlier. Your 'explanations' merely marginalize what is
otherwise a sound concept.

My system involves the placement of 22 satelites of about 10 metric
tons each into a single orbital plane - in a sun synchronous polar
orbit.

http://en.wikipedia.org/wiki/Polar_s...chronous_orbit

each satellite separated by pi/11 phase angle along the orbit.

The entire network consists of 30 orbital planes separated by pi/15
angle of longitude between planes.

A reusable heavy lift launcher with 500 metric tons of useful payload
places 22 satellites in the same plane. The satellites are deposited
along different phases of the orbit separated by pi/11 phase angle.
30 launches over an 18 month period provide total global coverage.

The reusable havy lift launcher is a variant of Bono's Manned Mars
launcher

http://www.astronautix.com/craft/bonhicle.htm

Except here, we have modified Space Shuttle ET - to be completely
reusable, with an annular aerospike at the base, powered by 3 Pratt &
Whitney RS-68 pump sets.

http://www.astronautix.com/engines/rs68.htm
http://www.astronautix.com/engines/aeroster.htm

The seven 710 metric ton elements, combined with the 500 metric ton
orbiter (including payload) comprise a 5,470 metric ton vehicle at
launch.

From these elements a smaller three element launcher, with a 200
metric ton orbiter may be constructed. A yet smaller one element
launcher, with an 500 ton second stage (similar to Ares concepts) with
a 70 ton payload to orbit is also doable.

These provide a range of capabilities from this basic set of
components.

Each 10 ton satellite is solar powered and uses a combination of gyro,
hypergolic (320 sec Isp) thermo-electric (600 sec Isp) and ion (1,800
sec Isp) propulsion for station keeping. 5 tons is allocated to
station keeping propellant.

The solar panels on each satellite may be augmented with a bandgap
matched laser system beamed from the New Mexico launch site - to
augment solar power for electrical propulsion maneuvers providing 4x
the rated power level during laser augmentation.

Each satellite has four open optical laser links to its nearest
neighbors. One ahead in the orbital plane, one behind in the orbital
plane, one immediately to the East, one immediately to the West in
different adjacent planes. Each orbit is slightly oblate, so that
while the period is the same for each, and they have the same semi-
major axis, they are oriented to pass over the poles at different
altitudes from each plane. furthermore, each plane is slightly out of
phase in its orbital placement so that they arrive above the pole at
different well defined times for each orbital plane. this way
collisions over the poles are avoided, and beam steering the open
optical lasers is simplified.

Optical communication through the shuttle window was carried out as
long ago as 1997 by Astronaut Lucid with a ground station in Hawaii.
Which was a repeat of a much earlier experiment done on Gemini 7

http://www.astronautix.com/flights/gemini7.htm
http://www.wtec.org/loyola/satcom2/03_06.htm

Phased array antennae on each of the satellites paint multiple
stationary microwave cells on the ground - using GPS signals along
with gyro signals to keep the virtual cells stationary and doppler
corrected for each satellite. The 'footprint' of each satellite's
antenna array is 1,850 km by 1,335 km. Across this footprint is
15,250 cells each 15 km across. Within each cell up to 50,000
channels may be active at one time. 50 billion channels may be active
across the entire network at one time.

The report below talks about optimizing phased arrays on the ground to
communicate with several satellites. Reverse the situation - having a
satellite communicate with several ground stations, and you get the
idea..

http://eo1.gsfc.nasa.gov/new/validat...ions_PPT.pd f

The launcher is estimated to cost $6.5 billion to build a fleet of
four - consisting of 28 booster elements and 4 orbiter elements -
creating four vehicles. The elements are interoperable between
vehicles. Three vehicles are 'active' one is designated 'spare'

The fleet of three launchers puts up 22 satellites into an orbital
plane every 18.6 days. Turn-around is 55.8 days per vehicle. The
spare covers the launch in the event the turn-around is missed. A
satellite is produced and installed in an orbiter every 20.3 hours
until all 660 satellites are deployed.

This 18 month production run is the first attempt at an assembly line
for spacecraft.

The satellites are estimated to cost $50 million each, so each launch
will have $1.1 billion in payloads. The cost of each launch is
estimated to be less than $210 million - which adds another $10
million per launch. This is a cost of $1,000 per kg a substantial
reduction in launch costs.

This launch system as noted before is very flexible. A 3 element
system, or a two stage single element system is possible. Payloads
can also vary.

So, after the comsat network is established, and $80 billion per year
is being earned by the network, the satellite production line can be
adapted to something like this;

http://www.astronautix.com/craft/marirect.htm

A payload for this vehicle could contain THREE Mars Direct capsules
per launch, and with a fleet of four vehicles, a fleet of 12 Mars
Direct vehicles could be deployed EACH synodic period.

Between launch windows to Mars there would be launches to support a
moon base built around the Mars Direct system - putting a dozen of
these payloads on the moon every 30 days.

On the unpiloted side, a 500 ton kick stage, would dock in LEO with a
500 ton payload stage, that would deploy a 20 GW inflatable solar
powersat - that beams laser energy to a large number of spots on Earth
and in cislunar space.

Humanity spends $4 trillion per year on energy to power a 15 TW
industrial infrastructure. Dviding 15,000 by 20 obtains 750 powersats
in GEO. At 42,164 km semimajor axis, and spread evenly around the
orbit, the 750 powersats would have a meann separation of 353.2 km.
With a 40% conversion efficiency each concentrator is 7 km in diameter
with a 6.82 km diameter concentrator area.

The 750 satellites, costing $6 billion EACH - would have a total cost
of $4.5 trillion - and generate $4 trillion per year.

A 20 GW infrared laser operating at 1 micron wavelength, can also
perform significant experiments in laser propulsion

http://en.wikipedia.org/wiki/Laser_propulsion
http://en.wikipedia.org/wiki/Specific_impulse

Thrust = mdot * Ve
Power = 1/2 * mdot * Ve^2
Ve = g0 * Isp

so,

Power = Thrust * Ve / 2

then

Thrust = 2 * Power / g0 * Isp

So a 20 GW system can provide the following thrusts

Isp = 500 sec -- 829,500 kgf
1000 sec -- 414,750 kgf
2000 sec --- 207,375 kgf
4000 sec --- 103,680 kgf

Which is quite sizeable.

A successful propulsion development program, that produced a 2000 sec
Isp capable engine, that worked with the existing launch elements
described earlier would produce a significant improvement in space
launch.

A single 710 ton reusable launch element carrying a 2,600 ton payload
operating at 2000 sec Isp could achieve orbit in a single stage.
Thrust at lift off would be 4,000 metric tons - or 25 of the engines
described above. That is, 500 GW would be needed - the output of 25
of the 750 satellites. The system could launch 2,600 metric tons
every 20 minutes or so.

A laser powered laser system on the ground, working in conjunction
with a solar powered laser array on orbit, would be capable of
significant improvment in our space faring capability. The fleet of
four booster rockets, consisting of 7 launch elements, could be
adapted to a fleet of 28 launch elements, with the construction of an
appropriate payload faring and propulsion system.

Reducing turn around from 60 days to 14 days, provides a means to
launch TWO vehicles per day each placing 2,600 metric tons on orbit.
This is over 216 metric tons per hour. If $1 trillion per year is
allocated to payload construction, costs of $530 per kg would have to
be achieved.

A 20 GW IR laser powersat could also power deep space probes and even
interstellar probes

http://www.sff.net/people/Geoffrey.L...ghtsail89.html
http://www.niac.usra.edu/files/libra...99/4Landis.pdf

One important use would be to create a near-sun powersat that operates
at the peta watt and exa-watt level to produce very powerful laser
beams and even anti-matter on an industrial scale. Such systems would
be evolutionary developments of the GEO based powersats and ground
stations, and would be placed in orbit using the very-heavy reusable
laser launchers, which are evolved from the heavy reusable chemical
launchers.

The revenue stream from space based assets, starting with comsat
network, and evolving to powersat network, provides adequate funding
for private development. Increasing value of the off world asset
base, and the products and services it provides to terrestrial
populations, eases environmental issues on Earth while providing a
long period of exponential growth in incomes and material wealth.

1 exa watt = 1,000 peta watts = 1,000,000 terawatts

This is sufficient to move asteroids using laser propulsion as well as
propel significant payloads interstellar distances - not just probes,
but space colonies. Similar near sol powersats placed at target stars
could create counter-propagating beams which would then be used to
create a navigational network for interstellar commerce, as well as
interplanetary commerce within each system.

Surveying and capturing rich asteroids for use in orbit around EArth,
using telerobotics to process those asteroids into useful products,
and deorbiting those products directly to users on the ground - and
anywhere in the solar system, creates a marked increase in human
capacity to produce material goods. At present $66 trillion in
economic activity is now supported by present resources and industry.
By capturing a few rich asteroids and placing tele-robotic systems to
process those asteroids using solar power on orbit, this economic
activity can be captured by a space based asset, and expanded
markedly. The average US citizen consumes 11x the material per capita
than the average for the balance of humanity. The average millionaire
consumes material resources at 20x the rate of the average American.
So, we can see that incomes have rather large upper bounds - that is,
economic activity in the peta dollar to exa dollar per year is
possible with human populations measured in the billions. Since very
wealthy nations and populations within nations do no reproduce at
replacement level, it is likely that at these extreme incomes humanity
will fall below replacement level. It is also likely that medical
advance would limit the rate of decline in human numbers even if
reproductive rates should fall.

The advent of interplanetary, and later, interstellar travel to the
general populace, along with a long term stability in human numbers,
not only means massive increases in wealth are possible, especially
when considering fully-autonomous robot systems used for production -
but also massive decreases in human density as we spread across even
the nearest of nearby stars.

The production of anti-matter from massive near-star stations would be
used to provide a secondary source of stored power aboard such ships,
as well as provide energy to smaller scale industrial systems - though
such systems would far out-class anything on Earth today.

At this level significant shaped payloads of iron-56 could be
experimentally collided at 0.3c in an attempt to create engineered
micro-black holes - which may have interesting properties that lead to
further propulsion and energy breakthroughs too speculative to discuss
here at length.

This is all doable over a span of the next 50 years.

Ian Parker wrote:
:
:There is a great deal that can be learnt about large conformally
:sterred system.
:

Want to try that one again in English?

:
:I do not deny that a WiFi project would be
:challenging. There are, as yet, no space rated products. There are
:abundant chips that would work on Earth. There are no reasons to
:suppose something could not be built.
:

And if wishes were fishes we'd all cast nets in the sea.

If 'hypotheticals' were systems, I'd be posting this from the Moon.

:
:Come to think of it there is nothing currently available that would do
:a tenth of what some people are suggesting. Space colonies - ha ha.
:

There are a lot more solid plans for those than for anything you dream
up.

:
:The Saturn drawings are still BTW available.
:

True.

:
:A Saturn could be produced from them.
:

False.

:
:BTW - The DOD has a mania for secrecy. How could
:anyone hostile produce a Saturn if NASA can't. Why can't the drawings
:be sold to anyone round the world?
:

Because launchers are on the ITAR Munitions List of prohibited
exports. Note that, despite your slur above, DOD has nothing to do
with what is and is not on the Munitions List.

:
:How is it that people who cannot even do a distillation of H2O2 are
:credited with the ability to produce not only WMD but also Saturns.
:Never try to figure out the workings of the military mind.
:

The preceding is merely the usual loony Artificial Stupidity System
(ASS) Chatterbot spewings that we know and love Ian for.

:
:It may or may not be better to start again, but NASA scrapped a system
:that worked with one that was twice as expensive. Conspiracy, or
:simple incompetance?
:

NASA didn't get a say.

You really don't understand AT ALL how things work, do you?


--
"Ignorance is preferable to error, and he is less remote from the
truth who believes nothing than he who believes what is wrong."
-- Thomas Jefferson