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Comment: Re:More religious whackjobs (Score 1) 215

by Rei (#49602743) Attached to: Native Hawaiian Panel Withdraws Support For World's Largest Telescope

It's the same reason why many of the oppose geothermal power, keeping Hawaii reliant on burning oil for most of its electricity. Also why there's opposition to even trying to redirect lava flows as most countries do when their people are threatened (with a number of successful redirects having been achieved).

Apparently Pele wants people to be ignorant of the cosmos, to destroy the climate, and to lose their dearest possessions without putting up a fight.

Comment: Re:This again? (Score 1) 416

by Rei (#49599695) Attached to: New Test Supports NASA's Controversial EM Drive

I've seen plenty of work on accelerator-drive heavy isotope reactors but nothing for light isotope reactors like lithium. Accelerator driven heavy isotope reactors still deal with many of the problems of conventional fission reactors - they're greatly improved in many regards, but still problematic (you still have some plutonium, you still have some fuel availability/cost limitations, you still have some long-lived waste, you still have some harder to shield radiation, you still have a wide range of daughter products making corrosion control more challenging, etc - just not to the degree of a regular fission reactor). A light isotope reactor using lithium would virtually eliminate all of these problems. And it has a higher burnup ratio, which is of course critical for space uses.

And while everything I've seen about past improvements in accelerator efficiencies and spallation process improvements, and what's being worked on now, suggests no limit any time soon on neutron production efficiencies - at least that's how it looks from the papers I've read. Plus, even if efficiencies couldn't be improved any further (there's not that much further one needs to go), one could hybridize a heavy isotope and light isotope reactor, using a heavy isotope target as a neutron multiplier to bombard the lithium. You'd require significantly reduced quantities of heavy isotopes relative to a pure heavy isotope reactor, and most of the energy from the lithium side could be as mentioned captured without Carnot losses, which is a big bonus. Any non-thermalized neutrons of sufficient energy would produce tritium as a byproduct, which of course would be a value-added product - in fact, given that the tritium-breeding reaction with 7Li and a high energy neutron yields a lower-energy neutron, the thermalization could potentially be done via tritium breeding in the first place. And tritium is a valuable product whether one has interest in D-T fusion or not.

I just think it's weird that I've not come across any work on a lithium-based accelerator-driven spallation reactor, and was just wondering if there's a reason for that. It certainly looks appealing to my non-expert eyes. I mean, it looks even cleaner and more fuel-available than D-T fusion, and looks closer to being viable on a full-system perspective. Versus accelerator-driven heavy isotope fission you get less power per neutron (about a quarter as much), of course, even accounting for Carnot losses in the former - but that's not what matters. Cost is what matters, and if you're eliminating the use of super-expensive fuel, not producing any costly-to-manage waste, have no incident radiation, no proliferation concerns, etc, you're completely changing the cost picture - without even considering the possible joint production of saleable tritium.

Comment: Re:Huh what?? (Score 1) 79

Yeah, it is a convoluted title, all right, and the lack of punctuation really scrambles it. But here's the breakdown, near as I can make out:

A Chapter of "Witch", Square Enix's Demo of Real-time CG system DX-12, Impresses at Microsoft Build

They're trying to cram too much into the title.

Comment: Re:Point proved (Score 0) 271

I own a 2001 Honda Insight hybrid modified to be a PHEV and plugged in nightly to charge on geothermal power.... and a Ford Ranger ;) The "why" is obvious, because I have regular needs to carry big heavy things, now that I own land in the countryside. Back when I had no such need... I didn't own any such vehicle.

I guess it's hard for him to imagine that a woman would have a need to carry large and/or heavy items?

Comment: Re:this is science, so you have to ask... (Score 4, Informative) 271

And the crazy thing is, they did consult with male colleagues before publishing. The reviewer just assumed that because two women submitted a paper with a conclusion that he disagreed with, that it's specifically because they're women "making ideologically biased assumptions" who refuse to talk to men.

Comment: Re:This again? (Score 0) 416

by Rei (#49596849) Attached to: New Test Supports NASA's Controversial EM Drive

Oh hey, since we've got (assumedly) a lot of physics nerds on this thread, and because my mind hasn't suddenly stopped being curious about random topics even though I grew old: here's one of my more recent things that left me with unanswered questions:

One of the commonly cited tritium-generating reactions is 7Li+n(>2.466 MeV) -> 4He + 3H. But is 7Li not also capable of transmutation to 8Li via slow neutron capture? If so would that not yield a 16.004 MeV beta to 8Be, and then immediately into 2 alphas with an additional energy of 0.092 MeV? If so, is there not potential for a future nuclear reactor? Spallation currently yields neutrons for about 25MeV each. If one could cut that in half or less - which I don't see any laws of physics in the way, just improvements in accelerator efficiencies and the spallation process - could this not yield a net positive, using direct deceleration/capture of the beta to generate power without having to suffer Carnot losses? And if so, would that not be a very desireable reactor - nonproliferative, abundant fuel, harmless waste, high ratio of fuel to energy conversion, direct spacecraft thrust possibilities, etc? Or am I totally off base here?

Comment: Re:This again? (Score 1) 416

by Rei (#49596423) Attached to: New Test Supports NASA's Controversial EM Drive

Haha, my concept as a child was to have a buoyant container on wheels in a tube full of water that would rise up, roll down a ramp on the other side, and re-enter the tube through an airlock on the bottom.

Wish my dad had taken the time to tell me why it wouldn't work rather than just saying "perpetual motion is impossible".

Comment: Re:This again? (Score 4, Insightful) 416

by Rei (#49596401) Attached to: New Test Supports NASA's Controversial EM Drive

Or, rather than all of physics being wrong, maybe they have an erroneous measurement setup.

That doesn't mean you shouldn't investigate anomalous measurements. But at this stage you shouldn't be writing fluff pieces with page after page of how much your new technology will change spaceflight. You should be publishing a paper with a name like "Measurement of anomalous thrust in a microwave apparatus operated in a hard vacuum" and trying to avoid the media insomuch as possible - and when you need to talk with them, trying to explain "we don't know what's going on... we have some theories but they're controversial... we need to do more testing." etc.

Comment: Re:Why? (Score 1) 108

by camperdave (#49591157) Attached to: Messenger's Mercury Trip Ends With a Bang, and Silence

Maybe this needs clarification - the probe was not "deorbited" i.e. deliberately smashed into Mercury in a controlled manner. They did all they could to keep it up in orbit as long as possible, but the fuel finally ran out and its orbit inevitably decayed and it finally impacted today.

Now fully out of fuel, the spacecraft smashed into a region near Mercury's north pole, out of sight from Earth, at about 20:00 GMT on Thursday.

That, to me, is the really sad part. They should have reserved enough fuel to deliberately crash it so that the impact could be seen and analyzed.

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