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#1 2004-10-04 13:46:01

smurf975
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From: Netherlands
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Re: Microwave Sattelites - Sending solar energy to from orbits.

I was just thinking of this technology.

As I understand it. It's using solar energy collected by sattelites and sending it to Earth or any other planet using microwaves.

However this will work not in reality especially on Earth as the atmosphere is too thick and the microwaves send to Earth will have extreme high loses in the form of resistance from the atmosphere.

So my point of this post is maybe using a guidance laser for this technology. Be it from Earth or the power sattelite or an assistive sattelite. That laser will create a path of ionized air in which the microwaves will travel. Or better said will want to travel as it's the path of least resistance.

What do you think of that?


Waht? Tehr's a preveiw buottn?

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#2 2004-10-05 14:13:17

C M Edwards
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From: Lake Charles LA USA
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Re: Microwave Sattelites - Sending solar energy to from orbits.

My guess: It won't work for this app, but don't throw away the cocktail napkin sketches just yet.

Orbit to surface microwave transmission losses due to the atmosphere occur mostly because of ionization in the air.  Creating an ionized "shield" between the transmitter and rectenna is unlikely to help. 

However, those ions are potentially useful.  What about adapting Nicholas Tesla's idea of atmospheric power transmission and using the ion trail itself to conduct electricity?  Keep enough power flowing down the pipe, and you won't need the laser anymore.


"We go big, or we don't go."  - GCNRevenger

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#3 2004-10-05 18:59:39

MarsDog
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From: vancouver canada
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Posts: 852

Re: Microwave Sattelites - Sending solar energy to from orbits.

However this will work not in reality especially on Earth as the atmosphere is too thick and the microwaves send to Earth will have extreme high loses in the form of resistance from the atmosphere.

Loss is low, less than 10^-2 db/km up to around 6 Ghz.

See fig 7 on page 8
Attenuation

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#4 2004-10-05 20:07:44

smurf975
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Posts: 401
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Re: Microwave Sattelites - Sending solar energy to from orbits.

My guess: It won't work for this app, but don't throw away the cocktail napkin sketches just yet.

Orbit to surface microwave transmission losses due to the atmosphere occur mostly because of ionization in the air.  Creating an ionized "shield" between the transmitter and rectenna is unlikely to help.

My bad I have done some further reading and noticed that the atmosphere has not that a big impact on microwaves. That is if you choose the right frequency (not that of water).

However there is the possible impact of all those microwaves heating the atmosphere a bit.

And as I gather from this site microwaves are a non ionizing EM wave. Those that do ionize are UV, X-rays, gamma rays and cosmic rays. However you can ionize a gas with microwaves but that's by heating it into a plasma. But then the power of the microwaves that would come down from the power satellites would be weaker then the sunlight hitting a square meter of the Earth's surface. But converting microwaves in to electricity has an efficiency of 98% compared to other forms of "green" power this is very high.

So forgot my post about the lasers as the atmosphere is not the problem just the cost to R&D and launch those satellites.
---

{edit}Marsdog had corrected me on this already


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#5 2004-10-05 20:24:02

smurf975
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Re: Microwave Sattelites - Sending solar energy to from orbits.

However, those ions are potentially useful.  What about adapting Nicholas Tesla's idea of atmospheric power transmission and using the ion trail itself to conduct electricity?  Keep enough power flowing down the pipe, and you won't need the laser anymore.

As I gather it electricity is just an EM wave with a low frequency. So an EM with a frequency of 50-60 Hz

But in power transmission lines the Voltage is many times higher to keep the resistance losses low. R= U/I (if I remember correctly U = Voltage, I = Ampere and R = Resistance).

So instead of ramping up the Voltage you increase the frequency of the EM wave. This gives you microwaves. And as I gathered microwaves don't need any ion trail or anything else to transmitted.

However I think they can only be transmitted from point to point like FM radio unlike AM radio which bounces of the higher atmosphere.


Waht? Tehr's a preveiw buottn?

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#6 2004-10-05 22:15:34

Euler
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From: Corvallis, OR
Registered: 2003-02-06
Posts: 922

Re: Microwave Sattelites - Sending solar energy to from orbits.

As I gather it electricity is just an EM wave with a low frequency. So an EM with a frequency of 50-60 Hz

No, electricity is the flow of electrons.  Elecricity and EM waves are very different things.

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#7 2004-10-06 09:16:21

MarsDog
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From: vancouver canada
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Re: Microwave Sattelites - Sending solar energy to from orbits.

Solar Power Satellites, (SPS), with beamed power are the answer to the high energy needed to launch and send to remote destinations. Centralized power has the economies of scale, and the ability to deliver large power.

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#8 2004-10-06 09:33:16

smurf975
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Re: Microwave Sattelites - Sending solar energy to from orbits.

As I gather it electricity is just an EM wave with a low frequency. So an EM with a frequency of 50-60 Hz

No, electricity is the flow of electrons.  Elecricity and EM waves are very different things.

Sorry, I understand it now I think. Photons are EM waves not?


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#9 2004-10-06 15:51:48

MarsDog
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From: vancouver canada
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Posts: 852

Re: Microwave Sattelites - Sending solar energy to from orbits.

Electricity, as in house 50/60 hz 110/220v is the movement of negative electrons in a conductor; in a solution the charged particle moving can be positive.
-
Alternating electrical current radiates and produces photons.
-
One is the motion of charged particles, the other is the motion of photons (electromagnetic waves)

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#10 2019-07-14 21:40:40

SpaceNut
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Re: Microwave Sattelites - Sending solar energy to from orbits.

Nasa does have work on this and some of the other topics have captured much of this.

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#11 2019-07-14 22:27:19

SpaceNut
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Re: Microwave Sattelites - Sending solar energy to from orbits.

NASA Wants to Beam Microwave Energy to Earth with a Solar Power Plant in Space When we first heard about the Solar Power Satellite via Arbitrarily Large Phased Array (SPS- ALPHA) – a proposed flower shaped solar power energy collector that beams down concentrated microwave energy back to Earth.

https://inhabitat.com/nasa-wants-to-bea … -in-space/

https://en.wikipedia.org/wiki/Space-based_solar_power

http://www.ssdl.gatech.edu/sites/defaul … 8-5714.pdf

https://www.energy.gov/articles/space-based-solar-power

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#12 2019-07-15 11:23:42

tahanson43206
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Re: Microwave Sattelites - Sending solar energy to from orbits.

For SpaceNut re #11 ...

Thanks for those neat links, and especially the flower shaped design.  I've been following SPS discussion since they became popular in 1977 or so, and am glad to see the significant advances.  My recollection is that physical generators were contemplated for creating the AC to drive the microwave transponders, and (if I understood the article correctly) engineers have arrived at all-solid-state solutions.

In the past few days I've had a chance to revisit Gerard O'Neill's "2081" which he wrote in 2080, about 40 years ago.  One chapter was devoted to SPS, which was interesting to me because the topic has just come back up on the NewMars forum, with an "ON MARS" twist that I like.

Speaking of Dr. O'Neill .... ssi.org is celebrating its 50th anniversary this year.  They've announced plans for a get-together in Washington (state) in September.

Tickets are pricey (out of my league) but hopefully someone in the forum membership can attend.

(th)

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#13 2019-07-15 16:33:52

SpaceNut
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Re: Microwave Sattelites - Sending solar energy to from orbits.

Microwave energy works via line of sight and on mars will work better since there is near zero atmosphere to attenuate the signal being sent from orbit. The transmission of power is also done with a target reciever that is as small as possible so as to keep the lose as minimal as possible. With a fixed target on the ground and an orbiting satelite this would mean a need for a synchronous satelite orbit so as to keep them over the target reciever.

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#14 2019-07-15 17:42:13

tahanson43206
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Re: Microwave Sattelites - Sending solar energy to from orbits.

For SpaceNut re #13 ...

Geosynchronous orbit at Mars is MUCH closer than is true on Earth, so the transmission distance is correspondingly less...

Google search for: geosynchronous orbit at Mars

Image result for where is geosynchronous orbit on mars
The Martian geostationary orbit altitude is only 13,634 kilometers (so an orbital radius of 20,428 kilometers, or about 3,000 kilometers inside the orbit of Deimos).Jun 27, 2013

The prospects for Solar Power Satellites at Mars keep looking better.

I'd like to offer a possible adjustment to your post #13 ... the idea of using dishes or concentrated antenna farms does not correspond with my recollection of plans from the early concepts.  In order to keep microwave density down so as to avoid injury to birds, animals or humans, the antenna farms (called rectennas) were planned to be quite large.

The situation at Mars is obviously different, so more compact antenna arrays might make sense.

Edit: https://space.stackexchange.com/questio … it-of-mars

The most fuel efficient way to enter an areosynchronous (same as geosynchronous, but Mars) would be to do a close pass of Mars to orbit, burning until the apoaerion is at the areosynchronous orbital height, and then burn again to have it be at a true areosynchronous orbital plane.

I vote for using geosynchronous as a term meaning "stationary orbit" without regard to the planet.  It will get ridiculous if we try to rename the word for every planet we settle or visit.

(th)

Last edited by tahanson43206 (2019-07-15 17:54:16)

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#15 2019-07-15 21:56:12

tahanson43206
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Re: Microwave Sattelites - Sending solar energy to from orbits.

https://www.researchgate.net/publicatio … g_analysis



Solar power satellite rectenna design study: Directional receiving elements and parallel-series combining analysis
Article (PDF Available) · November 1978 with 138 Reads

Abstract
Rectenna conversion efficiencies (RF to dc) approximating 85 percent were demonstrated on a small scale, clearly indicating the feasibility and potential of efficiency of microwave power to dc. The overall cost estimates of the solar power satellite indicate that the baseline rectenna subsystem will be between 25 to 40 percent of the system cost. The directional receiving elements and element extensions were studied, along with power combining evaluation and evaluation extensions.

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#16 2019-07-16 17:54:48

SpaceNut
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Re: Microwave Sattelites - Sending solar energy to from orbits.

https://en.wikipedia.org/wiki/Space-based_solar_power

Solar Power Satellite Offshore Rectenna Study pg count 254
https://ntrs.nasa.gov/archive/nasa/casi … 004047.pdf

tuning barrels with dipole reciever inside the direction control for collecting maximum energy

https://www.ursi.org/files/WhitePapers/ … ortMin.pdf

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#17 2019-07-16 18:26:53

tahanson43206
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Re: Microwave Sattelites - Sending solar energy to from orbits.

For SpaceNut re #16 ...

Thank you for the links in #16 .... I was impressed by the scope of the nasa study, and by the illustrations of what a rectenna farm would look like, as envisioned for 2.4 GHz, and to avoid ionization of the atmosphere due to excessive energy at 2.4 GHz.

The constraints on design would certainly be different on Mars ... no ocean swells, hurricanes, ice on the antenna elements and so on, but I expect the dimensions would be very similar.

The dimensions of the receiving field would (presumably) be identical, but there is plenty of land available on Mars.

One aspect of the Mars environment which I am hoping someone on the forum can find is the effect of dust on transmission of microwaves.

I would expect the impact to be much less than is the case with visible light, but would like to see the actual effect if it has been studied on Earth.

(th)

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#18 2019-07-16 20:09:57

SpaceNut
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Re: Microwave Sattelites - Sending solar energy to from orbits.

It is Iron for the most part and they are a poor conductor of electricity and if its magnetic enough then we could be creating lots of tiny magnets from the energy. So it would attenuate based on how much is in the air as it does with solar.
The atmosphere of mars will have a tiny amount of ice that would build up from water but there also would be daily co2 frost as well...

Link from discusion other topic
https://www.ascentsolar.com/bare-modules.html

These lend to be able to customize the power and voltage of an array that one would create.

The roughly 1000cm^2 panel x 10 to make up a meter would give just 100w which is not all that great but it does allow the flexibility to make different voltages to better match the batteries for charging and for use....

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#19 2019-10-03 14:30:29

tahanson43206
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Re: Microwave Sattelites - Sending solar energy to from orbits.

For anyone who may be familiar with the work of Ralph Nansen, I just learned that he is no longer with us.

Hello Tom,

I am sorry to report that Ralph passed away last year.

Best regards

Robert Godwin

CEO

I had written Apogee Books to find out if Mr. Nansen was still available for consultation.

(th)

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#20 2019-10-11 18:42:00

knightdepaix
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Registered: 2014-07-07
Posts: 225

Re: Microwave Sattelites - Sending solar energy to from orbits.

Can energy be sent to Mars in microwave then? So a specified range of wavelength in microwave becomes the currency of energy -- like the range of radiowaves for police or airplane communications --- be used. Any freshly generated, extra or waste energies in Venus or Earth orbits, on the Moon are all converted into those wavelength and beamed to Mars using microwave satellites.

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#21 2019-10-12 03:33:50

Terraformer
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Re: Microwave Sattelites - Sending solar energy to from orbits.

Microwave beaming over interplanetary distances? No. It's hard enough getting power over the 36,000 km from GEO.

On the other hand, beaming it from Martian orbit to the surface would be possible. There's plenty of room to set up the rectenna array, and no concerns about how it affects the environment.

Of course, if we can send large amounts of power from GEO to surface, we can build quite the interplanetary transport system. A ship accelerating at 2 m/s would reach 12 km/s by the time it leaves the range of the microwave beam. Then use the beam again to decelerate at the other end. For cargo, you could have a ship made up mostly of payload.

Last edited by Terraformer (2019-10-12 03:40:21)


"I guarantee you that at some point, everything's going to go south on you, and you're going to say, 'This is it, this is how I end.' Now you can either accept that, or you can get to work." - Mark Watney

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#22 2019-10-12 06:25:27

tahanson43206
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Re: Microwave Sattelites - Sending solar energy to from orbits.

For Terraformer re #21 ...

Per Mr. Google: geosynchronous orbit at mars

The Martian geostationary orbit altitude is only 13,634 kilometers (so an orbital radius of 20,428 kilometers, or about 3,000 kilometers inside the orbit of Deimos).Jun 27, 2013

What I ** really ** like about your post is the observation that there is a second entire set of business opportunities for a company that builds an SPS in Mars GEO, besides supplying ground stations with microwave power.

Vehicles designed to take advantage of microwave beams from stations at Mars would (presumably) feature large rectenna arrays.

I do not recall reading anyone writing about this before your post, although (of course) there could be something.

There is plenty of writing about LASER beams from Earth (or other sources) being used to directly influence objects, but your proposal (as I understand it) is to enable space vehicles to collect microwave power to accelerate small quantities of mass to high velocity, thus obtaining the best possible performance per unit of mass expended.

Ion drives are the first type of device that comes to mind, but mass larger than ions could certainly be accelerated.  Space writers have been discussing mass accelerators since Dr. O'Neill and his students began developing the idea in the 1970.

(th)

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#23 2019-10-18 04:50:10

elderflower
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Registered: 2016-06-19
Posts: 1,149

Re: Microwave Sattelites - Sending solar energy to from orbits.

GMO for a power gathering satellite would mean that the system could only be active for about half the time as the orbit passes over the night side every day. A polar orbit is in shadow for much less time over the year.
Several relay satellites in GMO should be used such that the polar orbiting power gathering satellites can send their microwave beams to them for onward transmission to ground stations. This may be subject to capacity reduction when there is a dust storm.
It  might be cheaper to install PV on the surface and provide power storage or round the planet transmission, in combination with differential pricing when it becomes commercial, to allow for night use. This is also subject to interference by dust storms but maybe to a greater extent as it affects energy capture. Round the planet transmission might be by microwave but dust storms would interfere with that too.

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#24 2019-10-18 07:41:25

Calliban
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From: Northern England, UK
Registered: 2019-08-18
Posts: 212

Re: Microwave Sattelites - Sending solar energy to from orbits.

elderflower wrote:

GMO for a power gathering satellite would mean that the system could only be active for about half the time as the orbit passes over the night side every day. A polar orbit is in shadow for much less time over the year.
Several relay satellites in GMO should be used such that the polar orbiting power gathering satellites can send their microwave beams to them for onward transmission to ground stations. This may be subject to capacity reduction when there is a dust storm.
It  might be cheaper to install PV on the surface and provide power storage or round the planet transmission, in combination with differential pricing when it becomes commercial, to allow for night use. This is also subject to interference by dust storms but maybe to a greater extent as it affects energy capture. Round the planet transmission might be by microwave but dust storms would interfere with that too.

About 11% of the time.  Mars has an equatorial radius of 3396km and Areostationary orbit lies some 17,032km above the surface.  So Mars will cast a shadow some 6800km wide on an orbit some 64,200km in circumference.

All the same, a solar power satellite will be in shadow for 2.7hours per Martian day.  To deal with that problem there would need to be either multiple satellites staggered along the orbit; energy storage; or deliberate shutdown of equipment at specific times of day.

Most likely a combination of the above.  On the plus side, the timing and duration of the power loss is entirely predictable down to the microsecond.  That makes it much easier to deal with.  There are some loads that we could simply switch off for 2.7 hours per day.  If people are asleep, then residential loads are lower anyway.  Heating is a function that can take place when power is abundant and switch off when it is not; because heat can be stored very efficiently and at very high energy density in bulk materials (think storage heater).

Last edited by Calliban (2019-10-18 07:47:43)


Interested in space science, engineering and technology.

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#25 2019-10-18 18:26:13

SpaceNut
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Posts: 17,340

Re: Microwave Sattelites - Sending solar energy to from orbits.

Space solar power - for Mars

We also have the natural charging effect from the suns solar winds on phobo Solar eruptions could electrify Martian moons to hundreds of volts...

https://www.space.com/38530-solar-wind- … hobos.html

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