Author Topic: Solar Power Satellites  (Read 103584 times)

Offline su27k

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Re: Solar Power Satellites
« Reply #340 on: 11/21/2022 02:51 am »
Another overview article from Scientific American: Is Space-Based Solar Power Ready for Its Moment in the Sun?

Quote
When inventor Charles Fritts created the first crude solar photovoltaic cells in the 1880s, one might have thought the achievement would rapidly revolutionize global electricity production. There is, after all, no power source cheaper, cleaner and more ubiquitous than sunlight. Yet despite enormous (and ongoing) technical advances making solar power ever more capable and affordable, some 140 years on it still supplies less than 5 percent of the world’s electricity. For all its benefits, solar power does have drawbacks that can limit its use—chief among them the fact that half the planet’s surface is in darkness at any given time.

Offline CameronD

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Re: Solar Power Satellites
« Reply #341 on: 11/21/2022 03:36 am »
DARPA powerbeaming RFI: https://sam.gov/opp/33e1fb52f3a04aeb8f099d71c85aca41/view

Tactical Wireless Power Beaming Technologies for Energy Web Dominance Request for Information

This Request for Information (RFI) from the Defense Advanced Research Projects Agency (DARPA)’s Tactical Technology Office (TTO) seeks technologies and innovative solutions for efficient, kilometer-range radio frequency (RF) kilowatt-class power beaming, distributed apertures for dynamic coherent beamforming, the conversion of RF to electrical energy, and RF energy relays in a lightweight, size-limited payload.

Maybe it's something else, but I read in passing that the recently-returned X-37B had a prototype SPS payload on board:

Quote
For example, we know that OTV-6 tested the U.S. Naval Research Laboratory's Photovoltaic Radio-frequency Antenna Module. This device, about the size of a pizza box, is designed to convert solar energy into microwaves, which can then be beamed down to Earth. Its work could help bring space-based solar power closer to reality, experiment team members have said.

https://www.space.com/space-force-x-37b-space-plane-otv-6-mission-ends
https://www.space.com/x-37b-space-plane-solar-power-beaming
« Last Edit: 11/21/2022 03:39 am by CameronD »
With sufficient thrust, pigs fly just fine - however, this is not necessarily a good idea. It is hard to be sure where they are
going to land, and it could be dangerous sitting under them as they fly overhead.

Offline Asteroza

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Re: Solar Power Satellites
« Reply #342 on: 11/21/2022 03:51 am »
DARPA powerbeaming RFI: https://sam.gov/opp/33e1fb52f3a04aeb8f099d71c85aca41/view

Tactical Wireless Power Beaming Technologies for Energy Web Dominance Request for Information

This Request for Information (RFI) from the Defense Advanced Research Projects Agency (DARPA)’s Tactical Technology Office (TTO) seeks technologies and innovative solutions for efficient, kilometer-range radio frequency (RF) kilowatt-class power beaming, distributed apertures for dynamic coherent beamforming, the conversion of RF to electrical energy, and RF energy relays in a lightweight, size-limited payload.

Responses to this RFI will be used to inform and explore future programs within the Tactical Technology Office that advance the ability of multiple ground assets to dynamically move energy across a network of small aircraft equipped with energy receiving and relay technologies. This RF power beaming and relay concept is expected to serve as a component of a more expansive energy web of power generation, transfer relays and receiving solutions, enabling the DoD to dynamically distribute energy resources to more flexibly deliver military effects.

Intellectual or other privileged or proprietary information contained in responses to this RFI will not be distributed outside of the Department of Defense (DoD) or U.S. Government employees from other Government agencies who are working with DARPA on this RFI. In the event that a new DARPA program is developed in response to this RFI and a solicitation is issued, no intellectual or other proprietary information received in response to this RFI will be divulged to  entities outside the U.S. Government.

I get the feeling DARPA feels an RF based tactical wireless power beaming solution is preferred, as it allows easier timesharing and split ops, compared to the 1-to-1 relationship of laser systems. Also, in theory it could just be another mode of advanced ESA radars, meaning any airplane with a substantial radar could provide power if it can be programmed for it (from fighters to AWACS), beaming power to small drones (kilowatt class is pretty small all things considered)

Offline LMT

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Re: Solar Power Satellites
« Reply #343 on: 11/21/2022 04:50 am »
Still, commercial GEO SSP must be a multi-km structure in a zone that's radar-blind to objects under 30 cm.  Impacts would be frequent and unavoidable.  Impact debris would not deorbit, but would continually intersect GEO, setting up further GEO impacts, most especially with the immense SSP structure itself:  i.e., a Kessler cascade generator. 

Choi and Choi are developing an SSP disposal patent which aims to transfer the retired structure to a distant Sun-Earth L4 / L5 graveyard.

Their patent development is ongoing, so one can only speculate.  Given the structure's great dry mass, a very-high-ISP electric propulsion system might be needed to limit propellant mass.  In that hypothetical case, high ISP corresponds with low thrust per kW, unavoidably, so disposal is slow; i.e., a spiraling orbit.  That leaves a risk on the table:  if a significant impact occurred while the structure were still in GEO, a Kessler cascade could kick off long before the structure reached safety.

Quote from: Choi and Choi 2021
...at present, [GEO satellites] are moved to the graveyard orbit by increasing their altitudes by 200-300 km. However, this approach is not applicable for giga watt-class space solar power satellites whose dimensions are several kilometers because it is highly possible for space solar power satellites to collide with other satellites in the graveyard orbit and cause Domino-like collisions (Kessler Syndrome). For this reason, the disposal of space solar power satellites could be the biggest dilemma...

What GEO SSP disposal methods might be both efficient and also robust against Kessler cascade?

Posts:  1 2 3

Video:  ESA:  Space debris 2017 - a journey to Earth
« Last Edit: 11/21/2022 05:02 am by LMT »

Offline TrevorMonty

Re: Solar Power Satellites
« Reply #344 on: 11/21/2022 07:15 am »
These power stations will need robotic assembly to build and maintain so shouldn't have end of life that requires disposal. They will be continually upgraded as needed.


Offline LMT

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Re: Solar Power Satellites
« Reply #345 on: 11/21/2022 03:24 pm »
These power stations will need robotic assembly to build and maintain so shouldn't have end of life that requires disposal. They will be continually upgraded as needed.

Is there a bot to repair PV on Earth?  Not to clean, but actually repair?

-

The unaddressed, blocking GEO SSP issue looms large.  Does it emerge from the blind spot, or does the blind spot grow around it?
« Last Edit: 11/21/2022 04:19 pm by LMT »

Online lamontagne

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Re: Solar Power Satellites
« Reply #346 on: 11/21/2022 05:37 pm »
These power stations will need robotic assembly to build and maintain so shouldn't have end of life that requires disposal. They will be continually upgraded as needed.

Is there a bot to repair PV on Earth?  Not to clean, but actually repair?

-

The unaddressed, blocking GEO SSP issue looms large.  Does it emerge from the blind spot, or does the blind spot grow around it?
On Earth, people are still much cheaper than robots.  So there is no user case.
In space, it should be the other way around, but the space robots don't exist yet.  SO it's all a bit theoretical.

Offline LMT

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Re: Solar Power Satellites
« Reply #347 on: 11/21/2022 08:30 pm »
These power stations will need robotic assembly to build and maintain so shouldn't have end of life that requires disposal. They will be continually upgraded as needed.

Is there a bot to repair PV on Earth?  Not to clean, but actually repair?

On Earth, people are still much cheaper than robots.  So there is no user case.

I asked if it exists.  You might just see if it exists.
« Last Edit: 11/21/2022 08:38 pm by LMT »

Offline jdon759

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Re: Solar Power Satellites
« Reply #348 on: 11/22/2022 01:45 am »
To deal with disposal Kessler issues, instead of having in the actual GEO belt,  why not have it a few 10s of km above, between GEO and graveyard? Make use of the impressive SEP array it will need for disposal to keep it orbiting at the right period.  Bonus is that if there is a debris-generating event, the debris will be flung into a higher orbit because it will be unpowered.  Disadvantage is being closer to GEO graveyard.  But if the SEP array was powerful enough, it could be above the graveyard instead.

The station would need to carry a lot more fuel though.  Probably need refuelling fairly regularly, and would be hard to rendezvous with.

Offline Twark_Main

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Re: Solar Power Satellites
« Reply #349 on: 11/22/2022 04:44 am »
Yes, space debris (or more accurately MMOD) is the main problem with SBSP, as I outlined here:

Not sure if this has been covered, but this thread seems a good place for it:

https://www.fnc.co.uk/discover-frazer-nash/news/frazer-nash-exploring-viability-of-space-based-solar-power-to-help-deliver-net-zero

The UK Government is looking for risky ventures, perhaps to try and compensate for the Brexit damage. They have now commissioned a study into Space Solar Power.

This is relevant to SpaceX because if the cost of launching a solar power station is less than the cost of building the solar arrays, then it might be possible to make a business case for it.

Launch cost = System Weight x Cost per unit mass
Quote
As part of the study, we are looking at the leading three SBSP concepts, from the USA (SPS Alpha), UK (CASSIOPeiA) and China (MR-SPS). SBSP experts John Mankins (USA) and Ian Cash (UK) – the inventors of the first two concepts – are supporting our study.

Problem with using SBSP en-masse is and always has been MMOD.

Micrometeoroid impacts blast away ~100x as much mass as the original impactor, and SBSP offers a huge target (you almost couldn't design something worse for MMOD unless you launch buckets of sand or something). So even if you dodge the big chunks, your solar panels will slowly get "eroded away" by untrackable MMOD. Since each impact multiplies the amount of tiny debris, you don't need too many SBSP installations before you're substantially increasing the MMOD environment in your chosen orbit.

Note that while the Kessler syndrome runaway threshold depends only on the total mass in a certain orbit, a large area satellites will be eroded away into fragments faster than a compact satellite.

One reaction at the time was that radiation pressure would take care of it, but apparently this is not the case.

Quote from: The Small Size Debris Population in the GEO Belt
The particles with the highest [area-mass ratios] show the largest spread in eccentricity and inclination. Many of the 6 µ objects had even decayed or were ejected from orbit. The debris of 50 μ size and larger, however, formed a fairly stable ring around GEO. The denser parts of that ring extended to about +/- 30° in declination (high ARM particles typically exceeded the maximum increase in inclination of 15°) and spreadover a radial distance of 500-1000 km.



In short, without non-conserved forces (eg drag), the radiation pressure causes the debris objects to "boomerang" back to the original orbit, then oscillate back and forth.
« Last Edit: 11/22/2022 04:48 am by Twark_Main »
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Offline LMT

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Re: Solar Power Satellites
« Reply #350 on: 11/22/2022 02:29 pm »
Yes, space debris (or more accurately MMOD) is the main problem with SBSP...

For delicate structures like GEO SSP, artificial debris is already the greater problem.  As the paper stated,

Quote
...in the sub-mm size range, [artificial] debris fluxes exceed the fluxes of natural meteoroids by at least a factor of 5.

And that debris is slower, at max ~ 800 m/s relative speed; therefore, unlike meteoroids, it can't eject impact debris from GEO-crossing orbits, e.g., to lunar apogee.
« Last Edit: 11/22/2022 03:47 pm by LMT »

Offline Twark_Main

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Re: Solar Power Satellites
« Reply #351 on: 11/22/2022 03:12 pm »
Indeed. "MMOD" includes both artificial and natural objects, but my point was more the micro- part (ie specifically referring to debris within that size range).
« Last Edit: 11/22/2022 03:19 pm by Twark_Main »
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Offline Asteroza

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Re: Solar Power Satellites
« Reply #352 on: 11/23/2022 06:55 am »
Chinese SPS technology maturation marching along...

https://twitter.com/CNSpaceflight/status/1595134353524535296

Online lamontagne

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Re: Solar Power Satellites
« Reply #353 on: 11/23/2022 01:00 pm »
These power stations will need robotic assembly to build and maintain so shouldn't have end of life that requires disposal. They will be continually upgraded as needed.

Is there a bot to repair PV on Earth?  Not to clean, but actually repair?

On Earth, people are still much cheaper than robots.  So there is no user case.

I asked if it exists.  You might just see if it exists.
There are window cleaner robots. https://solarcleano.com/en/gallery
There are no repair robots.  Anywhere.  Robots cannot yet repair things autonomously.

Offline edzieba

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Re: Solar Power Satellites
« Reply #354 on: 11/23/2022 01:44 pm »
These power stations will need robotic assembly to build and maintain so shouldn't have end of life that requires disposal. They will be continually upgraded as needed.

Is there a bot to repair PV on Earth?  Not to clean, but actually repair?

On Earth, people are still much cheaper than robots.  So there is no user case.

I asked if it exists.  You might just see if it exists.
There are window cleaner robots. https://solarcleano.com/en/gallery
There are no repair robots.  Anywhere.  Robots cannot yet repair things autonomously.
If you accept remote operation is possible, then the existing fleets of underwater ROVs that have replaced humans in many deep-sea installation, maintenance and repair roles are active real-world examples of robotic construction and repair of large structures and complex equipment.

Offline Robotbeat

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Re: Solar Power Satellites
« Reply #355 on: 11/23/2022 02:17 pm »
These power stations will need robotic assembly to build and maintain so shouldn't have end of life that requires disposal. They will be continually upgraded as needed.

Is there a bot to repair PV on Earth?  Not to clean, but actually repair?

-

The unaddressed, blocking GEO SSP issue looms large.  Does it emerge from the blind spot, or does the blind spot grow around it?
On Earth, people are still much cheaper than robots.  So there is no user case.
In space, it should be the other way around, but the space robots don't exist yet.  SO it's all a bit theoretical.
I maintain that with launch cheap enough to make SBSP feasible, humans would be cheaper than robots. And this isn’t bad. We want people to live and work in space, right? Not just take tourist flights?
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

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Offline TrevorMonty

Re: Solar Power Satellites
« Reply #356 on: 11/23/2022 03:53 pm »
These power stations will need robotic assembly to build and maintain so shouldn't have end of life that requires disposal. They will be continually upgraded as needed.

Is there a bot to repair PV on Earth?  Not to clean, but actually repair?

On Earth, people are still much cheaper than robots.  So there is no user case.

I asked if it exists.  You might just see if it exists.
There are window cleaner robots. https://solarcleano.com/en/gallery
There are no repair robots.  Anywhere.  Robots cannot yet repair things autonomously.
If you accept remote operation is possible, then the existing fleets of underwater ROVs that have replaced humans in many deep-sea installation, maintenance and repair roles are active real-world examples of robotic construction and repair of large structures and complex equipment.
Not good example as these ROVs are attached to very expensive manned surface ship. Still lot cheaper than deepsea divers to operate.
« Last Edit: 11/23/2022 03:54 pm by TrevorMonty »

Offline edzieba

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Re: Solar Power Satellites
« Reply #357 on: 11/23/2022 04:36 pm »
These power stations will need robotic assembly to build and maintain so shouldn't have end of life that requires disposal. They will be continually upgraded as needed.

Is there a bot to repair PV on Earth?  Not to clean, but actually repair?

On Earth, people are still much cheaper than robots.  So there is no user case.

I asked if it exists.  You might just see if it exists.
There are window cleaner robots. https://solarcleano.com/en/gallery
There are no repair robots.  Anywhere.  Robots cannot yet repair things autonomously.
If you accept remote operation is possible, then the existing fleets of underwater ROVs that have replaced humans in many deep-sea installation, maintenance and repair roles are active real-world examples of robotic construction and repair of large structures and complex equipment.
Not good example as these ROVs are attached to very expensive manned surface ship. Still lot cheaper than deepsea divers to operate.
That's a technical limitation due to lack of high-bandwidth wireless communication through several hundred metres of water, rather than a fundamental requirement. Some ROVs now use the tether for comms only, with power being entirely on-board (to allow for a single optical fibre as the link several kilometres long, rather than a bulky copper cable of much more limited length), which is directly analogous to a remotely operated spacecraft with on-board power and a wireless communication link.
Northop Grumman's Mission Extension Vehicles (and later the MRV and MEPs) are also operational remotely operated robotic spacecraft intended purely for servicing satellites.

Offline su27k

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Re: Solar Power Satellites
« Reply #358 on: 11/24/2022 02:43 am »
China to use space station to test space-based solar power

Quote from: SpaceNews
China intends to use its newly-completed Tiangong space station to test key technologies required for space-based polar power, according to a senior space official.

Robotic arms already operating on the outside of Tiangong will be used to test on-orbit assembly of modules for a space-based solar power test system, Yang Hong, chief designer of the Tiangong space station said in a presentation at the ongoing China Space Conference.

The test system will then orbit independently and deploy its solar arrays and other systems. It is likely to test and verify capabilities such as power generation, conversion and transmission.

Offline Asteroza

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Re: Solar Power Satellites
« Reply #359 on: 11/28/2022 10:14 pm »
Ian Cash, of CASIOPeiA fame, appears to be putting his money where his mouth is, and starting a company to ride the recent wind of ESA SPS studies.

https://www.spacesolar.co.uk

 

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