Science Fiction becomes, err, Science Fiction.

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Science Fiction becomes, err, Science Fiction.

Postby Workingman » 05 Apr 2024, 10:56

I am reading that the UK hopes to put up a mile wide array of solar panels into space to power 1 million homes. That would be 27 of them for all homes - just homes. Each array would need 68 launches for the 2,000 tonnes of panels and robot builders. The full kit would need 1,836 launches.

China, Japan, Europe (EU), India and the US are all looking at similar projects. Just think of the thousands of square miles of panels in space if they all go ahead! How many launches would be needed thus damaging the stratosphere and beyond?

Where will the mass of materials - rare earth metals etc. - come from? Oh, I know, we will mine the Moon, Mars and the asteroid belt - more launches.

Look up Dyson Sphere for more stupid ideas. :lol: :lol: :lol:
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Re: Science Fiction becomes, err, Science Fiction.

Postby cromwell » 05 Apr 2024, 12:41

What could possibly go wrong?
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Re: Science Fiction becomes, err, Science Fiction.

Postby Suff » 05 Apr 2024, 20:38

You are significantly out of date. In the next few weeks we will see IFT-4 of the SpaceX Starship. Expectations are that the booster will make a soft landing in the sea, instead of the 1,000+km/h crash the last one made and also that the ship doesn't tumble and makes it to re-entry without the plasma flow burning it up.

In that case SpaceX will have an operating rocket in disposable mode which can launch 200 Tonnes. 100 in re-usable mode but they haven't got there yet. However in disposable mode they could literally start lifting 200 Tonnes to space this year per launch.

This reduces the number of launches to 270 for all 27 arrays in disposable mode. 540 launches if it is in re-usable mode. Although the raptor 3 is being tested to ship 200 Tonnes in re-usable mode and 400 Tonnes in disposable.

Assuming 400 Tonnes, that comes down to 135 launches disposable. SpaceX is aiming for 140 Falcon9 launches this year. Although it is unlikely that SpaceX will do more than a few launches which are disposable in any one year. So back to 200 Tonnes re-usable or 270 launches.

Learning about Starship is important when assessing whether these technologies are feasible. For instance NASA has their SLS. It took them about 3 months to get the rocket on the stand, fuelled and launched. This was after a decade of converting it from space shuttle to SLS. Nothing new, just a reconfigure. 1 Decade, $100bn to make it and $1-$2 billion per launch.

Starship rocks up to the stand, fuels in about 2 hours and takes off. Done, gone. In all the tests I've watched fuelling is around 95% successful with only a very few aborts. This means the booster can launch a ship, land and do it again 2 or even 3 times a day. SLS is 8 million lbft thrust. Starship is 17.6m lbft thrust in the current incarnation (V2 raptor).

Now your 270 launches can, perhaps, take a year with a required 135 launch days for two launches per day. BUT, that is one booster, one stand. SpaceX has a second stand in build at Starbase and a third in Florida at the cape. Expect two or even four more stands/towers built in Florida. There are currently 4 boosters in stages of build with 1 complete and in testing and 3 more building rapidly.

Now your launch cadence begins to change dramatically. Even 3 stands, 3 boosters, say two launches of ships each launch day. Now we are talking 45 launch days. SpaceX is already doing over 100 now with the Falcon 9 and the falcon 9 requires weeks between launches for checks and refurbishment of the booster. Second stage is always disposable for non Dragon (crew and supply to ISS), launches.

Science fiction? You are entering that zone right now. Science fiction in terms of space launch has become science fact. Anyone who challenges our lift to space over the next decade needs to know what is already in progress and what is upcoming. Blue Origin (somehow I always think orifice), is also rapidly creating New Glenn. A 7m diameter heavy lift vehicle with around 60 Tonnes to orbit with fully re-usable first and second stages.

China is competing with SpaceX not with BO and certainly not with NASA.

But here is the reality for 2023 with Falcon 9. Which peaks at 16 Tonnes to orbit and needs weeks between launches for the boosters to be certified.

Welcome to living science fiction.

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Re: Science Fiction becomes, err, Science Fiction.

Postby Workingman » 05 Apr 2024, 22:45

It is not about St Elon''s Starship, FCOL, it is about the practicality of the proposed multi-region projects. Millions of tonnes and areas of km2 of solar panels floating about at 22,000 miles above the planet.

As I asked earlier: where are the materials to make them to come from? We don't have enough of them, especially the rare earth ones, on planet Earth.

Fusion, anyone?
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Re: Science Fiction becomes, err, Science Fiction.

Postby Suff » 06 Apr 2024, 20:03

I'm all for fusion but Solar panels are not really depleting earth resources.

The big bonus with space based solar is 24x7 power.

The other point is that getting them there became feasible in the last year.

Our planet is on a rapid move to a new technological state. Keeping up is hard.
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Re: Science Fiction becomes, err, Science Fiction.

Postby Workingman » 06 Apr 2024, 21:20

The figure of 68 launches comes from the people hoping to build this dream (the ones in the know) based on today's figures not some future hope for improvement.

The UK single one-mile-wide array (1 mile square) is 2,000 tonnes, 27 of them just for the UK is 54,000 tonnes.

We have no idea of the tonnage or area from the projects of China, the EU, the US, Japan, India and others. The number of 1-mile arrays could be vastly upwards of 50,000, probably a lot lot more.

Don't even try to pretend that there will be no depletion of the Earth's resources. We would need thousands of alchemists working 24/7 turning sawdust into the elements, Nikel. copper, silver to replenish them; and don't brush over the damage to the upper atmosphere.

By the time any of this gets anywhere near to becoming science fact we humans will be done for.
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Re: Science Fiction becomes, err, Science Fiction.

Postby Suff » 07 Apr 2024, 17:29

Yes the figures given by these companies do not factor in Starship because it is not operational yet.

If you follow SpaceX you will know that Elon did a presentation with the team at Starbase yesterday. 1m tonnes to Mars by 2045 is the goal.

To ship 1m tonnes to Mars requires 5 lifts of fuel for every ship that goes to Mars.

Solar arrays of 54k tonnes? Peanuts on the scale being presented.
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Re: Science Fiction becomes, err, Science Fiction.

Postby Workingman » 07 Apr 2024, 19:33

Nice body swerve of the materials problems once the previous players mentioned get involved.

That would be millions of tonnes.

Maybe we should fork up the sea bed for its nodules and screw up the marine environment instead.
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Re: Science Fiction becomes, err, Science Fiction.

Postby Suff » 08 Apr 2024, 19:25

Actually I was not so much ignoring rare earths as expecting that these cells would be Perovskite and not silicon.

It is the silicon cells which are currently being built out with rare earths to try and increase the very things that Perovskite provides naturally. Also I would expect wiring etc to be more aluminium than copper as the weight ratio is so much lower for space lift.

So I was not even factoring in the materials impact of solar cells, I was expecting them to be built out of the correct materials for the job given that they will be exposed to more light for longer and provide a true 24x7/365 power source.

It is not ignorance of the issue. More knowledge of the alternatives.

But, yes, with AI and bots, mining the regolith on the moon is a far more viable solution given that you can fire out of lunar orbit using linear accelerators. Only the materials which cannot be found on the Moon will come from Earth and over time that will move to the Asteroid belt. Saturn is waiting to be mined for fuel and also a bunch of the moons.

We have not yet even begun to look at the solutions out there and yet you are trying to constrain us instead of letting us get to a vast range of resources which will remove our power and carbon issues forever.

Yes ships like Starship are going to launch to Mars and it is going to create emissions. Right.

So how many emissions?

The UK burns around 132mtoe (millions of tonnes of oil equivalent), of energy annually. Now I took a figure of 5 launches for every 200 tonnes to orbit, assuming that every 200 Tonnes will go to Mars and will need the refuel. Honestly I don't think this is the case as the transport will evolve and use different methods. But lets assume this is the case.

That comes out at 30mtoe. roughly one quarter of the UK's Annual emissions to send 1m tonnes of load to Mars. But we're not talking Mars are we? We are talking about Earth Orbit. So let's half that as we will need more to push it to GTO but not as much as to push it to Mars.

Now we are talking 1/8th of ONE year to push up an array of 27 solar grids to reduce UK emissions dramatically. More than 1/8th I'm very sure. Every single year.

So let's stop having the Oil Industry scare tactics and start talking about real solutions which can be deployed within a decade by the technology already developed.

Yes I know Elon made it happen and you hate Elon. But face facts. The full flow staged combustion rocket engine was deemed impossible when the USSR failed to make it happen. Then the N1, again USSR, which had 29 rockets on it but it couldn't be controlled. So, again, it could not be done. Until SpaceX did it.

Our world changed last year when Starship blasted off the launch pad without exploding and made it well into the upper atmosphere before doing the loop the loop due to engine failures. But it changed even more so in November last year when it made it controlled to hot staging and the ship made it to space. Again, doubling down again this year, when the booster made it all the way to trying a soft landing before crashing into the sea and the ship made it to attempting re-entry.

Within a month we'll have a 4th test. Potentially within a month of that again, a 5th.

Humans are going back to space with a vengeance and why should we not at least try to make the best of our energy generation? Once nothing would have stopped us. When did we become so timid?
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Re: Science Fiction becomes, err, Science Fiction.

Postby Workingman » 08 Apr 2024, 21:17

What? Those perovskite cells that are largely theoretical and unproven at scale. The ones using toxic lead in their manufacture as well as those super-abundant elements we all fall over on the pavements - tin and gallium? The ones with stability, durability and power conversion efficiency problems. The ones the U.S. Department of Energy Solar Energy Technologies Office (SETO) have identified as having several key areas of improvement if they are to play a part in the future of photovoltaic technologies at scale. Those perovskite cells?

They are prone to UV degradation, but that is mitigated somewhat by Earth's atmosphere. In space? Hmm.

At the moment they are cm2 sized so not much good for powering 1 million homes from space. Millions upon millions more needed than silicon cells for a one-mile-wide array.

Suff, you accuse me of trying to constrain us. That is not the case, I am just trying to be realistic in what can be done. For the foreseeable future fossil fuels have their part to play, like them or not. We do need alternatives, for sure, but we need a whole raft of them not just the chosen few - solar and wind.

BTW the 'lift' of solar panels; weight / mass, is a bit of misdirection. One tonne of lead ingots is about 60 x 40 x 40 cm. Easy to fit in a Starship in one go. The same mass to volume of an unknown number of solar panels (all players involved) is anyone's guess.

It is not just the lift tonnage; it is also the volume. Capice?
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