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

Registered: 2018-04-27
Posts: 1,622

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: 17,340

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: 3,102

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: 1,622

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.



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