Author Topic: Space Solar Power with BFR  (Read 70551 times)

Offline envy887

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Re: Space Solar Power with BFR
« Reply #120 on: 06/14/2018 02:47 pm »
Doesn't Opportunity's situation put paid to the notion of using solar as the power source for a settlement?
No.

Quote
If dust storms can radically reduce insolation for weeks at a time, wouldn't that seriously endanger a base?
No, not a properly planned one.

Quote
Are there practical back-up systems/energy storage solutions that could cover that amount of time with severely reduced PV output?

Yes. The PV required for making fuel is several megawatts per BFS. Even severely reduced, it should be plenty to run critical systems. You wouldn't make fuel in a dust storm.

Even if the storm is bad enough that the PV is unable to keep critical functions running and the batteries charged, each BFS is a giant chemical battery holding about a megawatt-year of energy. Simply run boiloff through a small LNG genset and you have power, water, and heat.

Offline Tulse

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Re: Space Solar Power with BFR
« Reply #121 on: 06/14/2018 02:50 pm »
So, in other words, because of the power needs of ISRU, the settlement will be vastly overpowered for its non-ISRU needs?

Offline guckyfan

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Re: Space Solar Power with BFR
« Reply #122 on: 06/14/2018 02:52 pm »
Much depends on data gathered now. Is the extreme Tau value short lived and local or can a dust storm have those values for extended times in one location? Up to now the state of information was that even during major dust storms solar would yield at least 20% of normal values which would be enough by far to keep essential services running. Just power down all major power consuming industrial processes.

Offline LMT

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Re: Space Solar Power with BFR
« Reply #123 on: 06/14/2018 05:00 pm »
even during major dust storms solar would yield at least 20% of normal values which would be enough by far to keep essential services running.

"Mars is hard."

And even harder than you indicated.  The 2007 dust storm's atmospheric light transmission was < 5% for a period of ~ 3 weeks above Spirit, and ~ 4 weeks above Opportunity.  Shutdown.  Lemmon et al. 2015, Fig. 8.

At a SpaceX facility "essential services" would be more than just a system clock.  Propellant plant services, for example, and unavoidably.  Earth-return launch windows must be honored, irrespective of weather or season.  Winter storms occur:  power systems must have scale and redundancy to accommodate.

Hard, isn't it?



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"After the last of these images were taken, Opportunity was forced to halt imaging -- and most other operations, including regular communication with Earth -- to conserve its battery power and ride out the storm."

Refs

Lemmon, M. T., Wolff, M. J., Bell III, J. F., Smith, M. D., Cantor, B. A., & Smith, P. H. (2015). Dust aerosol, clouds, and the atmospheric optical depth record over 5 Mars years of the Mars Exploration Rover mission. Icarus, 251, 96-111.
« Last Edit: 06/14/2018 07:57 pm by LMT »

Offline envy887

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Re: Space Solar Power with BFR
« Reply #124 on: 06/14/2018 06:35 pm »
And even harder than you indicated.  The 2007 dust storm reduced light transmission by more than 95% for a period of ~ 3 weeks above Spirit, and ~ 4 weeks above Opportunity.  Shutdown.  Lemmon et al. 2015, Fig. 8.

At a SpaceX facility "essential services" would be more than just a system clock.  Propellant plant services, for example, and unavoidably.  Earth-return launch windows must be honored, irrespective of weather or season.  Winter storms occur:  power systems must have scale and redundancy to accommodate.

PV power output is not entirely linear with direct optical transmission, since there is indirect light transmission.

And propellant production absolutely DOES NOT have to continue during a dust storm. That's absurd. Just size the system assuming some weeks are lost to a storm, that is only a few percent of the time between synods.

Offline LMT

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Re: Space Solar Power with BFR
« Reply #125 on: 06/14/2018 07:30 pm »
And even harder than you indicated.  The 2007 dust storm reduced light transmission by more than 95% for a period of ~ 3 weeks above Spirit, and ~ 4 weeks above Opportunity.  Shutdown.  Lemmon et al. 2015, Fig. 8.

At a SpaceX facility "essential services" would be more than just a system clock.  Propellant plant services, for example, and unavoidably.  Earth-return launch windows must be honored, irrespective of weather or season.  Winter storms occur:  power systems must have scale and redundancy to accommodate.

PV power output is not entirely linear with direct optical transmission, since there is indirect light transmission.

And propellant production absolutely DOES NOT have to continue during a dust storm. That's absurd. Just size the system assuming some weeks are lost to a storm, that is only a few percent of the time between synods.

When the atmosphere transmits < 5%, nonlinear response and indirect lighting aren't helpful.

You realize those 4 weeks were just the peak of the storm, yes?  The storm ran for 2 months.  In martian winter, off-equator PV would be essentially disabled for the entirety of the storm. 

Imagine 5 months of winter in Hellas Basin, with daily clear-sky PV averaging 10% of summer max.  Then intersperse 3 months of storms, all causing near-complete PV shutdown for the duration.

Quantifying:  What challenge does that scenario present to winter propellant production for, say, 10 spacecraft?  How might you structure and scale things to accomplish the loading?
« Last Edit: 06/15/2018 12:09 am by LMT »

Offline envy887

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Re: Space Solar Power with BFR
« Reply #126 on: 06/14/2018 07:53 pm »
x
And even harder than you indicated.  The 2007 dust storm reduced light transmission by more than 95% for a period of ~ 3 weeks above Spirit, and ~ 4 weeks above Opportunity.  Shutdown.  Lemmon et al. 2015, Fig. 8.

At a SpaceX facility "essential services" would be more than just a system clock.  Propellant plant services, for example, and unavoidably.  Earth-return launch windows must be honored, irrespective of weather or season.  Winter storms occur:  power systems must have scale and redundancy to accommodate.

PV power output is not entirely linear with direct optical transmission, since there is indirect light transmission.

And propellant production absolutely DOES NOT have to continue during a dust storm. That's absurd. Just size the system assuming some weeks are lost to a storm, that is only a few percent of the time between synods.

When the atmosphere transmits < 5%, nonlinear response and indirect lighting aren't helpful.

You realize those 4 weeks were just the peak of the storm, yes?  The storm ran for 2 months.  In martian winter, off-equator PV would be essentially disabled for the entirety of the storm. 

Imagine 5 months of winter in Hellas Basin, with daily clear-sky PV averaging 10% of summer max.  Then intersperse 3 months of storms, all causing near-complete PV shutdown for the duration.

Quantifying:  What challenge does that scenario present to winter propellant production for, say, 10 spacecraft?  How might you structure and scale things to accomplish the loading?

This should probably go in one of the Mars threads, not SSP.

Hellas at mostly 40+ degrees south is probably further than you want to go with solar as primary, and more equatorial locations are better initially. But even there, just make it bigger, and do propellant production mainly in the summer.

Offline LMT

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Re: Space Solar Power with BFR
« Reply #127 on: 06/14/2018 08:13 pm »
Quantifying:  What challenge does that scenario present to winter propellant production for, say, 10 spacecraft?  How might you structure and scale things to accomplish the loading?

Hellas at mostly 40+ degrees south is probably further than you want to go with solar as primary, and more equatorial locations are better initially. But even there, just make it bigger, and do propellant production mainly in the summer.

The quantitative challenge does press hard.  Adding "a few percent" just isn't enough.  So sure, scaling all systems for "feast-or-famine" high-speed summer loading is an option.  It would incur a real mass penalty, but it's an option.

Offline alexterrell

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Re: Space Solar Power with BFR
« Reply #128 on: 11/18/2020 07:28 am »
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.

Offline Slarty1080

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Re: Space Solar Power with BFR
« Reply #129 on: 11/21/2020 01:35 pm »
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.
I can't help but feel the idea will run aground somewhere on the rocks of transmission loss, continually dropping solar panel prices and the technical uncertainties around massive solar arrays in orbit. But we shall see. It's a neat idea but I question the practicality / economics of it.
My optimistic hope is that it will become cool to really think about things... rather than just doing reactive bullsh*t based on no knowledge (Brian Cox)

Offline aero

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Re: Space Solar Power with BFR
« Reply #130 on: 11/21/2020 02:43 pm »
Maybe we'll have to wait for Space Elevator development. Then we could transmit power from space to the surface over transmission lines down the Space Elevator shaft!
Retired, working interesting problems

Offline Anderqual

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Re: Space Solar Power with BFR
« Reply #131 on: 11/21/2020 02:57 pm »
Would it be possible to harvest static electricity generated during dust storms to offset solar loss?

Offline john smith 19

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Re: Space Solar Power with BFR
« Reply #132 on: 11/21/2020 03:34 pm »
I can't help but feel the idea will run aground somewhere on the rocks of transmission loss,
JPL found ways to phase lock cavity magetrons (something that was not believed to be possible) to make low cost high power phased array transmitters in the 1970's.
Quote from: Slarty1080
continually dropping solar panel prices
Which only work during the day. Above 800Km daylight is 24 hours long. At GEO there would be no pointer shifting but much higher losses.
Quote from: Slarty1080
and the technical uncertainties around massive solar arrays in orbit. But we shall see. It's a neat idea but I question the practicality / economics of it.
And yet somehow the ISS stays in orbit.
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline john smith 19

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Re: Space Solar Power with BFR
« Reply #133 on: 11/21/2020 03:36 pm »
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.
And they will probably conclude (as earlier studies did) that without cheap and rapidly reusable launch systems the design is uneconomic.
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline rakaydos

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Re: Space Solar Power with BFR
« Reply #134 on: 11/21/2020 04:15 pm »
Would it be possible to harvest static electricity generated during dust storms to offset solar loss?
There's no way you could be aware, but "Triboelectricity" has a single, violently aggressive supporter on these forums. his evidence is too sketchy to garner any support though. It isnt looking good.

Offline Twark_Main

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Re: Space Solar Power with BFR
« Reply #135 on: 11/21/2020 05:51 pm »
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.
« Last Edit: 11/21/2020 05:52 pm by Twark_Main »
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Offline Slarty1080

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Re: Space Solar Power with BFR
« Reply #136 on: 11/22/2020 01:05 pm »
I can't help but feel the idea will run aground somewhere on the rocks of transmission loss,
JPL found ways to phase lock cavity magetrons (something that was not believed to be possible) to make low cost high power phased array transmitters in the 1970's.
Quote from: Slarty1080
continually dropping solar panel prices
Which only work during the day. Above 800Km daylight is 24 hours long. At GEO there would be no pointer shifting but much higher losses.
Quote from: Slarty1080
and the technical uncertainties around massive solar arrays in orbit. But we shall see. It's a neat idea but I question the practicality / economics of it.
And yet somehow the ISS stays in orbit.
Yes the ISS stays in orbit, but it does not have "large" solar arrays on the gigawatt scale. The proposed solar plant would be roughly 10,000 times bigger. What could possibly go wrong?
My optimistic hope is that it will become cool to really think about things... rather than just doing reactive bullsh*t based on no knowledge (Brian Cox)

Offline M.E.T.

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Re: Space Solar Power with BFR
« Reply #137 on: 11/22/2020 01:20 pm »
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.

Interesting. Does this then, by extrapolation, ultimately invalidate the idea of a Dyson swarm as well?

Offline savantu

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Re: Space Solar Power with BFR
« Reply #138 on: 11/22/2020 01:40 pm »
In my view solar power is irrelevant long term for space activities. You need nuclear. Hopefully the renaissance of nuclear invest for low power reactors on ground/space will do to BEO exploration what Spx did to transportation.
The first attempts to Mars will be solar, but their multitude of issues already mentioned will probably mean by 2025 you're launching disassembled reactors and getting them online in space.

Offline Twark_Main

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Re: Space Solar Power with BFR
« Reply #139 on: 11/23/2020 12:20 am »
Interesting. Does this then, by extrapolation, ultimately invalidate the idea of a Dyson swarm as well?

I would think so. :(


by 2025 you're launching... reactors

Are there any reactor programs that have a prayer of being ready by then?
« Last Edit: 11/23/2020 12:20 am by Twark_Main »
"The search for a universal design which suits all sites, people, and situations is obviously impossible. What is possible is well designed examples of the application of universal principles." ~~ David Holmgren

 

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