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Point out news stories, on the net or in mainstream media, related to polywell fusion.

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Aeronaut
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Post by Aeronaut »

So practical manned space exploration is going to favor power density.
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zapkitty
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Post by zapkitty »

Aeronaut wrote:So practical manned space exploration is going to favor power density.
Yep, power or ultra-clever materials technology. And fusion gives us that power.

But there's a caveat with powered shields... power failure.

Power plant or shield projector failures would normally not be a big deal re: exposure as you'd have ample time to fix things or even get spares from home base before the dose piled up..

But if you're caught in the inner system with shields down and the Sun tosses something nasty your way... well, without sufficient passive shielding for solar particle events you'd just fry.

So even with shields you'd want a passive solar storm shelter at the very least.

... shields and shield projectors and "shields down"... waitaminute here...

Well, anyway, the shields described would just love the naturally high voltage output of certain types of fusion plants... in fact they'd prefer gigavolt ranges for handling GCR if they could get it...

Skipjack
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Post by Skipjack »

So even with shields you'd want a passive solar storm shelter at the very least.
Yeah, I think that would be something you would want anyway. But it would only have to be a very small shelter, just enough for everyone to hide out in there until the worst is over. Then go back to business as usual.

Aero
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Post by Aero »

Skipjack wrote:
So even with shields you'd want a passive solar storm shelter at the very least.
Yeah, I think that would be something you would want anyway. But it would only have to be a very small shelter, just enough for everyone to hide out in there until the worst is over. Then go back to business as usual.
How long do solar storms last? And how long a storm would you design for? One sigma, two sigma, three sigma length? Or six sigma? It could make a difference in the size and resources needed within the shelter.
Aero

CaptainBeowulf
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Post by CaptainBeowulf »

For a moonbase I would be inclined to dig out a hole in the regolith and put the base mostly "underground". You can put the regolith you've dug out back on top when you've put your modules in place. Even in the event of a power failure, you should be ok then (obviously you would have surface features too, like observation ports, a rover hangar, airlocks, landing pads etc.).

However, I think that an electrostatic magnetic shield may very well be necessary for interplanetary craft (including an earth-mars or moon-mars vessel).

I also remember NASA having a webpage where they speculated that an electrostatic magnetic field could function as a solar sail. The solar wind might push against it, pushing it into the outer system.

Such an effect would make a very good solar sail (it could be easily switched on and off, the spacecraft could be compact, and it would not be brittle - erosion from spacedust and micrometeorites would be less of a threat). However, such an effect could also be a problem if you wanted to have your shield on while flying sunwards (ie. inbound from Mars or the outer system to Earth).

Perhaps if you can make your magnetic shield very small, just a small bubble surrounding the ship, it wouldn't have much of a solar sail effect. However, if you expanded it, you'd get the solar sail effect. That would be cool.

zapkitty
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Post by zapkitty »

Aero wrote: How long do solar storms last? And how long a storm would you design for? One sigma, two sigma, three sigma length? Or six sigma? It could make a difference in the size and resources needed within the shelter.
They are short-term events. Exceptional flares can last 3 hours or more although the geomagnetic events they and CMEs trigger at Earth can last for days.

But they are triggered by solar magnetic instabilities and those, like sunspots, tend to appear in clusters.

As for how bad to plan for? At some level it's best to have experts chime in, and I'm definitely not an expert :)

Of course the experts are learning too... years after the radiation protection levels for ISS were written up they are still adding shielding to the sleeping areas in order to cut down on lifetime dosage.

But at this point it is safe to say that Bigelow modules will offer improvement over current station hulls in radiation shielding. Even without numbers the very physical makeup of the modules ensures that much.

And it's also safe to say that current spacecraft designs cannot afford the mass or the power to shield deep space missions against GCR and can offer only limited protection against SPEs.

And fusion says... well... something like "... mass margins for lead and boron armor on the hab to handle solar flare x- and gamma rays... additional margin for shield projectors to handle the heavy stuff... and the power to run the projectors... margin for a storm shelter with a meter of shielding... ... ... no problem!"

And it's safe to say that even if all you had to offer for a Mars trip was a ship that had little protection but could make the trip in 5 weeks... well, the line of volunteers would still stretch out of sight.

And as this is a DPFF thread I'll add this: while polywell may eventually take the lead, the FF module would seem to be ideal for initial forays into the realm of spaceborne fusion power plants.

But first you need to actually test the concepts on orbit so back to the FOOF thread for me ;)

zapkitty
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Post by zapkitty »

CaptainBeowulf wrote:For a moonbase I would be inclined to dig out a hole in the regolith and put the base mostly "underground".
Digging the hole at the bottom of a deep crater will increase your protection by putting kilometers of regolith between the base and stuff coming in from the horizon.

93143
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Post by 93143 »

The evidently common lava tubes may minimize the amount of excavation necessary...

Skipjack
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Post by Skipjack »

Nextbigfuture once again has a nice (small) update on Lerners DPF- research:
http://nextbigfuture.com/2010/04/dense- ... s-and.html
Not quite sure what to make of it yet. They do seem to be making progress though.

Brian H
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Updates

Post by Brian H »

Some of that is new, some is outdated. More on the focusfusion.org site; check the latest 5 new postings.
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jrvz
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Post by jrvz »

Giorgio wrote:Yes, there was a couple of projects funded by NASA for a moon base shielding based on electrostatic/magnetic fields.
One of the final reports is this:
http://www.niac.usra.edu/files/studies/ ... Buhler.pdf
...
High energy particles are deflected by magnetic fields, but in the process they emit synchrontron radiation http://en.wikipedia.org/wiki/Synchrotron_radiation. These are X or gamma rays, primarily forward along the particle's original path (like headlights). Maybe the resulting radiation dose is too small to require shielding, but I'm surprised the article doesn't even mention it.
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rcain
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Post by rcain »

Skipjack wrote:... They do seem to be making progress though.
i was about to agree and say, i really like the frequent updates on their site at present (Dr Nebel take note). But, just now i discover theyve let their domain renewal slip and their site is currently completely unavailable.

Brian H
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Post by Brian H »

rcain wrote:
Skipjack wrote:... They do seem to be making progress though.
i was about to agree and say, i really like the frequent updates on their site at present (Dr Nebel take note). But, just now i discover theyve let their domain renewal slip and their site is currently completely unavailable.
Called Eric about it; they've had lotsa calls. He says it's paid up, and they don't understand why it's down. They're working on it; the ISP is "MyDomain", which sounds like it's a small outfit. :(
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rcain
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Post by rcain »

internic shows domain expiry in 2011, though record only just updated today On:26-Apr-2010 11:23:04 UTC - currently still in AUTORENEWPERIOD.

maybe propagating still. check again later should be ok.

Brian H
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Post by Brian H »

rcain wrote:internic shows domain expiry in 2011, though record only just updated today On:26-Apr-2010 11:23:04 UTC - currently still in AUTORENEWPERIOD.

maybe propagating still. check again later should be ok.
Yep, back up now. Seems there was a mis-directed renewal email, etc., etc.
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