NASA injects cash into solar electric motor NASA has announced it has awarded a contract worth $67m to Aerojet Rocketdyne to "design and develop an advanced electric propulsion system that will significantly advance the nation's commercial space capabilities, and enable deep space exploration missions". The Advanced Electric Propulsion System (AEPS) will "potentially …
"Poo ionizes nicely. Perfect propellant"
Agreed. I see the future of inter-planetary space travel, the NASA Special Meat Phal Curry, guaranteed to ionize your poo and cause ejection at more than 65,000 mph.....
The SEP drive is a wonderful new method of crossing interstellar distances in a few seconds; without all the coronary health implications of sitting around in restaurants, dangerous mucking about with improbability factors, or tedious mucking around in hyperspace.
It simply makes the problem of how you get from A to B very fast, Somebody Else's. Arcturan Megafreighters now use this drive as standard, and can cross the galaxy in seconds with full axial-tilt shifting payloads. The Galactic Navy is also investing heavily in the technology.
Recent research has suggested that the exhaust from such massive SEP field generators manifests exclusively amongst organic lifeforms living in Plural sectors. Sometimes, clues as to their origin can be tracked by observant phenomenologists. Concern has arisen about the possibly disastrous consequences of the explosive growth of this Problem Displacement technology. The group SIYSYM* has cited the recent test runs of the Galactic Navy's new battlecruisers, Trump, Cruz, and Farage, as being potentially catastrophic for primitive lifeforms.
Solve It Your Selves, You Morons
Who'd like to convert one of these into some sort of lamp?
It really looks quite cool though I'm guessing highly impractical owing to atmosphere without some elaborate vacuum system.
(I'm also trying to convince the wife a small nuclear reactor would be a fetching piece in the garden pond what with the cherenkov radiation glow, boom because accidents happen.....)
So xenon huh, the same gas they use in strobe light bulbs? So a really bright blue-white glow coming out the tails of spaceships exactly like Star Wars, Star Trek and the vast majority of all video games happened to portray for the last several decades what "space thrusters" would look like..... I'm also pretty sure there must be an excellent physics/chemistry-based reason for using Xenon as opposed to any other propellant.
I'm really starting to notice how very often nature/logic always finds a way to ensure that scientific/technical breakthroughs "just happen" to turn out looking exactly the way Hollywood and video game developers already portrayed them, even though they almost certainly could have had no actual scientific basis for their portrayal, just cool-factor.
From my perusals on the pedia that is wiki, the main reason for using xenon is that it doesn't corrode and knacker your equipment in the same way that the old mercury ions used to.
Xenon presents an erosion / sputtering hazard like mercury, but that was addressed by using an ion engine (Hall effect thruster) without an accelerator grid across the nozzle. Otherwise, it does avoid chemical corrosion and spacecraft contamination present from mercury or alkaline metals. It's also fairly dense as a gas so you can pack a lot of reaction mass into a relatively light pressure bottle.
Xenon's other winning trait is a low ionization potential (~1200kJ/mole) compared to the other noble elements, though it is relatively high compared to champions of ionization like cesium (~500kJ/mole).
Sorry to inject a note of caution, but where are they intending to get a supply of Xenon from? Apparently it exists in the Earth's atmosphere as a trace element at a proportion of 1 in 11.5 million, and is extremely difficult and expensive to extract. The cost of producing sufficient quantities to propel an interstellar craft would be prohibitive, and its storage would present insurmountable problems too. OK for small scale laboratory demonstrations, but not in the real (future) world.
Sorry to inject a note of caution, but where are they intending to get a supply of Xenon from?
All current xenon production is from the atmosphere. At 1 part per 11.5 million by weight, Earth's atmosphere "only" has 4.4 billion metric tons of it. Assuming it ceases to be economically viable to extract when half has been consumed, it will be a while before the annual (1998) production of 5000m^3 (~10,000kg) depletes this reserve.
and is extremely difficult and expensive to extract.
Well, the going rate (in 1999) is about $12 per liter, or $2/g. That's not very comparable to, say, gold.
Xenon is chosen because it is inert (neutral nitrogen is also inert, but tends to become somewhat more chemically active when ionised), is elemental rather than molecular (e.g. Xe rather than N2), so physicists can treat it more like an 'ideal' gas, it has a high atomic mass (131) as opposed to the molecular mass of neutral nitrogen (28), which is important because thrust is proportional to mass, and has a lower ionisation potential than molecular nitrogen (12.13 eV vs 15.58 eV), which determines the amount of energy required to ionise it in the first place before accelerating it as reaction mass.
That real things often mirror Sci Fi. And there are two reasons. One is that inventors/engineers/scientists such as myself grew up on the stuff, said wow, I'd love to make it real, and some of us did just that. It's very gratifying, but also disappointing we've not done better than we have (that little issue about what people think is worth putting money into).
Coming from the other side, many if not most Sci Fi writers (at least of what's often called "hard" scifi) are themselves not exactly ignorant of science. In order to get readers to suspend disbelief long enough to tell their stories, they often do their homework to come up with something at least not trivially dismissable. Some are scientists themselves (Asimov for an obvious example) and others have friends who are to help with what might be called "theoretical error checking" on ideas.
My handle (look it up on youtube) should give you some indication that for some people, it's about the thrill of the chase more than the bucks. Guys like me are rare as a proportion of humans, but there are a lot of humans, and quite a few like me who invent for the fun of it. And we grew up on Sci Fi - whether deliberate or not, it influences how we think.
And yes, xenon is a good choice for an ion thruster for plain old scientific (mV) reasons. SciFi may not have "known" this - and by the way, Hg is also blue, but most people correctly associate blue light with higher energy stuff - It just worked out.
The other option in electric engines is Argon, and that is a ghost of the cost of Xenon, and ALMOST as good. However if the difference between good and a bit better is a few thousand dollars, and you are looking at a spacecraft that costs hundreds of millions (or more?) and only needs a hundred kilos of fuel, buying the expensive fuel makes sense.
f the economics of it change in some way, Argon would be almost as good, and makes up about 1% of our atmosphere. (Oh god, some got into my mouth!) Actually about 1% of a lot of planet's atmosphere.
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