Burning Questions About Hydrogen Wire

Scientists at Harvard have recently announced the long-sought creation of the metallic form of Hydrogen.  The last I recall reading about progress towards this goal, perhaps a decade ago, researchers were using diamond anvils.  Take two perfect diamonds, set them opposite each other, place the sample substance in between, and then squeeeeeeeze.  As it turns out they’re still using that same kind of apparatus with some refinements to make the compression surfaces more atomically perfect.

In the circles of material science this milestone really is a big deal.  The theoretical properties of metallic hydrogen are intriguing: room-temperature superconductor, super-high energy rocket fuel.  The article goes into some pie-in-the-sky speculative detail about what wonderful things could be done with this new substance, as most science articles are wont to do.

Let me just point out a couple of things:

  1. There is no theoretical means of mass production.  When these people talk about this room temperature superconductor revolutionizing energy storage and transmission, bear in mind that we have no idea how to scale up production to a level which would be useful or economical for anything other than special-purpose 1-off big-money project.  Think: military, or space exploration, or special-built supercomputer.
  2. Unlike most fuels we use metal hydrogen must have all its energy put into it.  Gasoline, in contrast, has a rather high specific impulse, but what makes it so darn attractive is that the energy is already present in the hydrocarbons we pump out of the ground.  With a few chemical tweaks we can modify it into a very useful fuel, but it is an energy source, whereas metallic hydrogen would be useful as an energy medium, i.e., a form of energy storage.  That is to say, the energy from metallic hydrogen will have to come from some other source and then be stored in the form of metallic hydrogen, but that energy has to come from somewhere else.  Therefore, it’s useful for rockets where volume and mass are at a premium, but very little else as compared to, for example, hydrocarbons.
  3. When considering the superconducting applications of metallic hydrogen, don’t forget the other potential use: high specific-energy rocket fuel.  Now consider the implication: superconducting metallic hydrogen wire would be made of rocket fuel.  We’re used to thinking of wiring as a fire hazard, but mostly because it can overheat and melt, and spark, and thereby set other things on fire, but hydrogen metal wire will itself burn enthusiastically.  Maybe not the kind of stuff you’d want anywhere near your person or things you care about.

So: Metallic Hydrogen.  Superfantasic as the fuel of the world’s tiniest spacecraft, but otherwise, well…  Not so great.


EmDrive Pushing Forward

Here’s more news as a followup to “EmDrive – Propulsion Revolution” – NASA continues to test the EmDrive reactionless thruster with promising results, and they’re making progress with theory development to explain the otherwise inexplicable test results.  There’s a report that experiments show EM drive works in a vacuum, thus dispelling the leading debunking theory that the measured thrust was an artifact arising from internal thermal convection.  What’s more, the working theory helps explain disparate results between U.S. & UK & China teams.

This is exciting!  Read the latest here, although sadly there’s no word yet on what it sounds like.

EmDrive – Propulsion Revolution

NASA confirms: EmDrive works – propulsion without propellant. Yes, I’d say that’s OMG WTF big news!  According to the homepage FAQ, 1st generation will be suitable for spacecraft thrusters, and the 2nd generation (which assumes use of superconducting cavities) should be suitable for terrestrial ground vehicles.  I wonder if the EmDrive goes “weeble-weeble-weeble“…

Teflon Slips By NASA

NASA tells us that “Curiosity”, the new Mars mission, is A-OK and ready to go!  Oh, and by the way, the much-touted rock sampler will probably be contaminating its samples with Teflon.  This will register as carbon when the rock is analyzed – and the rover will be looking for carbon.  How much of it will be from the sample, vs. the rover itself?  NASA won’t be able to tell.  Not to worry!  NASA has workarounds – for example, they could just, y’know, not use the drill and roll over the rocks, crushing them beneath the wheels!  Yeah, that’ll work!

OK, maybe they’ll be able to mitigate the problem, but what ticks me off is that it was entirely avoidable; an “unforced error” in baseball parlance.  Space science is hard, no doubt about it, but this problem had nothing to do with long-duration operation in an extreme environment, or the hazards of the unknowns.  I’m OK with those kinds of problems; they literally come with the territory.  In this case they’re doing what – they’re banging a hammer on a rock.  The hammer has Teflon seals.  Teflon is soft and squishy, and might get on the rock.  Teflon is made of 2/3’rds carbon, one of the elements for which they’re looking.  Nobody noticed until now.

Ladies and gentlemen, this is not a problem inherent in the difficulty of “rocket science”.  If nothing else this is a testing issue; but NASA will often skip tests and double-checks in order to shunt that money towards more science – or cost overruns.  If they do their job right the first time it won’t make a difference, but if they don’t then – well, they say, “Oopsie, not to worry, we’ll figure it out and still do a lot of science!”

I don’t know if private industry would do so much better or cheaper than NASA.  NASA, after all, relies on private industry to do a lot of their grunt work.  Private industry doesn’t have much of an interest in finding life on Mars (nor does NASA , “officially” at least); there isn’t much of a market for it versus space tourism or supply runs to the space station.  Still, NASA hasn’t covered themselves in glory in this instance, and it’s one of many, so I’d like to see if hungry competition might create better results.

Memristors: Rewriting Electronics Theory

[by Mr.Hengist]

Researchers at Hewlett-Packard’s Information and Quantum Systems Lab have created the memristor, the last to be created of the four fundamental circuit elements, joining resistors, capacitors, and inductors. It’s big news in the Electrical Engineering community as it completes the set and, with development and refinement, should lead to significant new capabilities in the field of electronics, not the least of which is a reduction in the leakage current which plagues modern computer chips.

Leakage current in chips is akin to the problem of a leaky aqueduct: more leakage means inefficiency in water transport – and a lot of soggy ground around the leaks. Leakage current is why chips get hot when they run; in personal computers, modern CPUs leak so much electricity that they need at a minimum fan-assisted heatsinks to keep from self-destructing when under load, and motherboards now use cross-connected heatpipes and heatsinks on support chips to keep them from burning themselves out. It’s a problem that’s gotten bad and is getting worse; the main driver of increased chip speed for the last two decades has been feature shrink – smaller circuitry – which in turn has the natural side effect of making the circuitry faster, but feature shrink also results in an increase in leakage current. The writing on the walls has been clear for years: if this problem is not mitigated it will be the limiting factor to what has been the most effective means of making computers faster and cheaper.

Memristors may or may not be a big part of the solution to the leakage current problem in semiconductors, but this discovery is not just adding another class of widget to the toolbox of electrical engineers: it’s going to rewrite their textbooks on electronics. As this article in EETimes explains:

The hold-up over the last 37 years, according to professor Chua, has been a misconception that has pervaded electronic circuit theory. That misconception is that the fundamental relationship in passive circuitry is between voltage and charge. What the researchers contend is that the fundamental relationship is actually between changes-in-voltage, or flux, and charge. Such is the insight that enabled HP to invent the memristor, according to Chua and Williams.

What astonishes me is that such changes are possible even today. Just as the discoveries of dark energy and dark matter have turned upside-down our understanding of the composition of the universe, so too are there discoveries being made which render our understanding of basic principals in well-studied fields moot. How did we get so far while still not knowing this? The tragedy of scientific understanding that it is usually wrong, but it is only through self-correction that we know that to be so, and in that self-correction we see the strength of science.

So long, and thanks for the all the bits!

[by Mr.Hengist]

Two hundred and seventy million miles of vast dark emptiness from here and high above the ecliptic plane slowly spins the high science of two decades past. At fifty million miles an hour Ulysses has been marking the monotony with only a gradual shift in the positions of the stars, including our own, at which it has stared relentlessly for these many years. The heat of her radioisotope generator has been largely depleted and can no longer power all her instruments; her hydrazine fuel has dwindled down to a pittance of only seven months’ supply. The end is near and approaching fast; come November, one year into its third trip around the sun, Ulysses’ low whisper of data will finally fall silent as she succumbs to the cold sleep in deep space.

Yet, just as the forever lost vessels of our early seafaring past are only now being recovered from the floors of the seas, perhaps it will be the children of your children who will one day return her home to Earth, but home she will be brought as a prized artifact of exploration from our time.

I figure it’s either that, or the Klingons will use it for target practice, but twenty quatloos says we get to it first.