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#26 2019-10-24 09:50:15

Registered: 2018-04-27
Posts: 7,326

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

For Calliban re #24 and topic in general...

In recent times, someone suggested scooping up CO2 from the atmosphere of Mars, using a scoop on a tether let out from Phobos.

SpaceNut, if you can find the discussion, I'd appreciate your adding a link in a post after this one.  I'd like to see credit go to the contributor.  It might well have been void, although there are certainly others who might have offered suggestions along that line.

However, I'd like to combine that idea with others that have been posted in the NewMars forum.

First, there is the idea of siting solar power satellite equipment on Phobos, for the purpose, NOT of powering locations on the surface of Mars, worthy as that project would be, but ** instead ** powering vehicles designed to match orbit with incoming vessels, in order to help them to dock with Phobos.

I expect that unsupervised landings on Mars will become unacceptable, after the resident community reaches a size sufficient to defend itself.

The most likely scenario for a Quarantine station would be on Phobos, where living creatures can be observed for sufficient time to be sure they are not carrying threatening biological agents, and where every physical object on the incoming vessel can be examined in minute detail to be sure it does not contain threatening components or materials.

The inspection could include examination of all software on board the vessel, although transmission of malignant software via tight beams from Earth (or elsewhere) is the greater danger.

A tug/challenge vessel could be powered by microwave radiation from Phobos, and the mass to be expelled could be CO2 collected from the atmosphere of Mars as described above.

Edit: a discussion at this site: … ic=21544.0

suggests that CO and O are a practical fuel/oxidizer combination for the scenario presented here.  The ISP is below 300, but the raw material is readily available (assuming the tether/scoop concept works) and  solar power is certainly available at Phobos.  I would envision the tug/challenge vessel loading a tank of liquid CO2 and using microwave power to disassociate the molecules as needed.  That would eliminate the need for separate tanks and reduce the problem of boil-off.


Last edited by tahanson43206 (2019-10-24 10:17:56)


#27 2019-10-24 16:55:42

From: New Hampshire
Registered: 2004-07-22
Posts: 23,099

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

The tethered climber to lower cargo to mars with less fuel is what I remember for the moon. Space Towers and Skyhooks on the page as well on pg 3 are some of the figures

I put forth a a roller track to allow for the teher to go in and out with the rotation of the moon. Since the moon spins as well as circles the planet it makes for a poor means to send power to mars due to constant tracking of the surface and to turn them off as we are not in alignment with mars or the solar energy for the panels to recieve the energy with.

Using the moon for an animal quarantine sound reasonable but the long during should have already been long enough.

Aiming a microwave beam at a moving target and not heating the content of the ships sounds sort of dangerous.

We talked about atmospheric scoups in a few topics as a means to gather gas for orbital use in some of the venus topics but the drag of the tube to get enough volume to draw up the tube as it would pull and slow what ever is dragging it through the atmospher.


#28 2019-10-28 18:26:24

Registered: 2015-01-02
Posts: 4,615

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

We didn't have efficient 1MW to 10MW gyrotron technology to send the power back to the planet from orbit, within the mass constraints required of a satellite, until a few years back.  We do now, thanks to the nuclear fusion program's never-ending quest for lighter, smaller, more efficient, and higher-power gyrotrons.  That's the real game changer for orbital solar power transmission systems.  If we combine electric propulsion for efficient station keeping with thin film arrays and current state-of-the-art 170GHz to 300GHz gyrotrons, then we can deliver power a couple hundred kilometers through a significant atmosphere, such as the one Earth has, with acceptable losses.

As few as 6 of these things could beam power to any point on or around a planet, as required.  Supplying the dark side of a planet through re-transmission is the most novel use of solar power satellites.  Taking an antenna to wherever power is required sure beats dealing with setup of any energy production or storage equipment.  The cost of things that don't have to be built or transported to still get reliable power is staggering.  The only real degradation the equipment is subject to comes in the form of radiation and debris, but that takes awhile to significantly degrade a suitably hardened system.  Aside from the frequency-associated breakdown distance within the atmosphere, there's no dust, water vapor, or atmosphere to deal with when generating power.  Transmitted power could simply be injected into the grid at a point where interference is minimized.  Within limitations, beam shaping can focus the power to account for antenna dimensions.

Apart from the mundane but necessary requirement for continuous power, there is also the possibility of using these things to deliver thermal power to rockets to enable launches and orbital transfers with the efficiency and thrust of nuclear thermal rockets.  Very fine control is required to direct the satellite's power to a rocket accelerating to orbital or even escape velocity, but modern microchips and laser ring gyros can provide the precise beam steering control required to support this type of operation.  So, while we may not power cities here on Earth from orbit in the short term, we could drastically reduce the quantity of rocket fuel required to reach orbit to something closely resembling the quantity of fuel a fighter jet requires for its similarly short period of useful operation.


#29 2019-10-28 19:03:29

Registered: 2018-04-27
Posts: 7,326

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

For kbd512 re #28 and other posts in this topic and elsewhere relating to solar power satellites

I ** really ** appreciate your addition of encouraging news about (relatively) recent developments which ** may ** allow a business case for SPS to close.

Earlier this year, you spent some time showing how Ammonia can be prepared, transported and used for a variety of energy consuming applications.

This may be to much to ask right now, but (by any chance) can you imagine a scenario where the combination can be put together, somewhere on Earth, to deliver a positive cash flow after investing in an SPS including launch using all-recovered vehicles, the ground station, ammonia preparation, delivery and consumption?

If that scenario can be shown to close in today's competitive environment, with fossil fuels still in their glory days, then it will surely do even better when fossil fuels begin to fade out.



#30 2021-07-10 18:30:07

From: New Hampshire
Registered: 2004-07-22
Posts: 23,099

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

our topic on energy beaming from orbit....

tahanson43206 wrote:

For RobertDyck .... re #142

Thanks for picking up on the Dyson sphere error, and adding the Ringworld follow up ...

The figures you've posted are interesting (to me for sure) and they might be right, but they might be in need of adjustment ...

The efficiency of 30% ** might ** be the ratio of power delivered to the ground compared to the amount of power subtended by the solar panels or mirrors.

Could you clarify that?

One thing I am confident needs adjustment ... almost NONE of the power transmitted through the atmosphere is lost.

If you can find a reference for ** that **, I'd be amazed.

My corresponding estimate is 3% at most.

The beam from GEO has to travel through only 100 miles (162 km).

I asked Google for assistance to support my 3% guess, but since I'm on an ancient computer at the moment, I can't pursue the links.

Radio propagation - Wikipedia › wiki › Radio_propagation
Radio propagation is the behavior of radio waves as they travel, or are propagated, from one ... Several different types of propagation are used in practical radio transmission ... At different frequencies, radio waves travel through the atmosphere by ... The RF noise burst from the lightning makes the initial part of the open ...

Atmospheric Attenuation - an overview | ScienceDirect Topics › topics › engineering › atmospheric-attenuation
The atmospheric transmission efficiency of the microwave beam depends on ... to eliminate periodic RF power fading caused by dispersion in optical fibers and ...

Which layer of atmosphere is important for transmission of radio waves?
Do radio waves pass through the atmosphere?
Does humidity affect RF transmission?
OSA | Studies on characterizing the transmission of RF signals over ... › abstract

Apr 27, 2009 · In this work, we aim at experimenting in actual deployment environment scenario the performance of RF signal transmission using a FSO link.
Radio-Frequency Communication › spp › military › docops › afwa
In the upper levels of the ionosphere, ions are thinly spread and remain highly charged. ... The different layers in the atmosphere are caused by the different ... TESTWhen high-powered transmitters and efficient antennas are used, the surface ...

RF Safety FAQ | Federal Communications Commission › ... › Radio Frequency Safety

This efficient absorption of microwave energy via water molecules results in rapid ... intensity of the RF environment at a given location in terms of units specific to ... It is common that not all antennas are used for the transmission of RF energy; ...

Electromagnetic radiation - Radio waves | Britannica › science › electromagnetic-radiation › Radio-waves

Transmission therefore involves not a single-frequency electromagnetic wave but rather a ... This width and the decrease in efficiency of generating. ... miles) above Earth's surface in which the atmosphere is partially ionized by ultraviolet light ...

Telecommunications media - Radio transmission | Britannica › topic › Radio-transmission

In atmospheric propagation the electromagnetic wave travels through the air ... ionosphere (as in shortwave radio; see below The radio-frequency spectrum: HF). ... An important measure of the efficiency with which a transmitting antenna ...
[PDF] The effect of temperature and humidity on the transmission of radio ... › cgi › viewcontent

other factors affect radio waves such as which frequency is most efficient and transmits the strongest radio ... lower temperature and lower relative humidity in the atmosphere. ... Figure 2.2 Radio Frequency energy losses due to scattering.

RF Path and Absorption Loss Estimation for Underwater Wireless ... › pmc › articles › PMC4934316

Jun 16, 2016 · The intricacies presented by the underwater environment are far more ... To design an efficient and robust UWSN, the characteristics of underwater ... transmission distance and nature of communication in underwater.
[PDF] Radio frequency propagation differences through various ... › ark: › metadc5801 › high_res_d › thesis
selection, tuning and maintenance, increasing the efficiency of the network and ... Null: There is no difference in signal transmission through Styrofoam, Lexan ... To propagate radio waves through Earth's atmosphere, the energy must be.
Related searches

I see a pdf in that list ... I'll try to pull it down ...Nope ... the site is protected.

The ** truth ** lies somewhere between 70% and 3%



#31 2021-07-10 19:18:09

From: New Hampshire
Registered: 2004-07-22
Posts: 23,099

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

RobertDyck wrote:

Last I read, microwave beamed power has only been successful across a short distance, a few miles, less than 10. And only 30% collected at the other end. Transmitted through the atmosphere requires at least 100 km (62.1 miles). Above that is tenuous atmosphere, so yea, a lot. And getting through the ionosphere will be non-trivial. It's been a number of years, so let's see what I can find.

Wikipedia: Wireless power transfer

Power transmission via radio waves can be made more directional, allowing longer-distance power beaming, with shorter wavelengths of electromagnetic radiation, typically in the microwave range. A rectenna may be used to convert the microwave energy back into electricity. Rectenna conversion efficiencies exceeding 95% have been realized.[citation needed] Power beaming using microwaves has been proposed for the transmission of energy from orbiting solar power satellites to Earth and the beaming of power to spacecraft leaving orbit has been considered.

Power beaming by microwaves has the difficulty that, for most space applications, the required aperture sizes are very large due to diffraction limiting antenna directionality. For example, the 1978 NASA study of solar power satellites required a 1-kilometre-diameter (0.62 mi) transmitting antenna and a 10-kilometre-diameter (6.2 mi) receiving rectenna for a microwave beam at 2.45 GHz. These sizes can be somewhat decreased by using shorter wavelengths, although short wavelengths may have difficulties with atmospheric absorption and beam blockage by rain or water droplets. Because of the "thinned-array curse", it is not possible to make a narrower beam by combining the beams of several smaller satellites.

For earthbound applications, a large-area 10 km diameter receiving array allows large total power levels to be used while operating at the low power density suggested for human electromagnetic exposure safety. A human safe power density of 1 mW/cm2 distributed across a 10 km diameter area corresponds to 750 megawatts total power level. This is the power level found in many modern electric power plants. For comparison, a solar PV farm of similar size might easily exceed 10,000 megawatts (rounded) at best conditions during daytime.

Following World War II, which saw the development of high-power microwave emitters known as cavity magnetrons, the idea of using microwaves to transfer power was researched. By 1964, a miniature helicopter propelled by microwave power had been demonstrated.

Japanese researcher Hidetsugu Yagi also investigated wireless energy transmission using a directional array antenna that he designed. In February 1926, Yagi and his colleague Shintaro Uda published their first paper on the tuned high-gain directional array now known as the Yagi antenna. While it did not prove to be particularly useful for power transmission, this beam antenna has been widely adopted throughout the broadcasting and wireless telecommunications industries due to its excellent performance characteristics.

Wireless high power transmission using microwaves is well proven. Experiments in the tens of kilowatts have been performed at Goldstone in California in 1975 and more recently (1997) at Grand Bassin on Reunion Island. These methods achieve distances on the order of a kilometer.

Under experimental conditions, microwave conversion efficiency was measured to be around 54% across one meter.

A change to 24 GHz has been suggested as microwave emitters similar to LEDs have been made with very high quantum efficiencies using negative resistance, i.e., Gunn or IMPATT diodes, and this would be viable for short range links.

In 2013, inventor Hatem Zeine demonstrated how wireless power transmission using phased array antennas can deliver electrical power up to 30 feet. It uses the same radio frequencies as WiFi.

In 2015, researchers at the University of Washington introduced power over Wi-Fi, which trickle-charges batteries and powered battery-free cameras and temperature sensors using transmissions from Wi-Fi routers. Wi-Fi signals were shown to power battery-free temperature and camera sensors at ranges of up to 20 feet. It was also shown that Wi-Fi can be used to wirelessly trickle-charge nickel–metal hydride and lithium-ion coin-cell batteries at distances of up to 28 feet.

In 2017, the Federal Communication Commission (FCC) certified the first mid-field radio frequency (RF) transmitter of wireless power.

So real-world experiment resulted in 54% across one metre.


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