Cesium (in the +1 state) appears to be barely toxic at all. Wikipedia puts its LD50 around that of sodium. Cesium metal is extraordinarily dangerous, but it’s so reactive that none of it will survive long enough to get anywhere near the ground.
> Same line of thinking that results in depleted uranium tank shells.
Yeah, since neither was particularly toxic, and both offered significant performance gains over the alternatives. (Uranium is extremely dense, self-sharpens on impact instead of mushrooming, and catches fire after penetration giving you an incendiary payload for free. Supposedly, nothing else comes close for tank rounds)
The problem here is that armor piercing rounds need to be made of heavy metals in order to work and heavy metals are generally toxic. Even lead, which old fashioned bullets and shells are made of is toxic.
Uranium is more likely to distribute that toxicity in a convenient dust cloud, though. Tungsten and lead for the most part stay in one piece on impact.
Perhaps I should have said "not outrageously toxic" or something of that sort, because that does not sound worse than the stuff we make normal bullets out of - lead.
That's true! Lead does tend to stay more clumped up than uranium dust. But isn't it also easier for lead to become bioavailable and/or enter the water supply?
If you call “toxic” and non biodegradable “political”, I agree with you. I think you will find that countries that expect the fighting to be largely in their backyard selected Tungsten and the countries that fight “overseas” selected Uranium.
Ah, yes, because all lead bullets turn into a thousand degree cloud of dust, which you can later accidentally inhale or adsorb through your skin decades afterwards.
The concerns I have around the project are more in the FAA certification process than in the EPA. I don’t believe this is a partisan issue; it’s stalled under both Democrat and Republican administrations.
I think that the 737-Max issue will put so much more spotlight and brakes on anything that seems remotely risky, that the alternative fuels program (which was already struggling as you note) is unlikely to make serious near-term progress.
Almost tangentially, I believe that we have a viable fuel technically (G100UL) that is likely to be (or be the template for) the fuel ultimately selected, albeit possibly a decade or more in the future.
Apparently back in the day they were seriously considering ClF5 as the next generation oxidizer for rocket propellants. Implying that the rocket exhaust would to a large extent consist of HF and HCl. Yikes!
Equally funny is where someone thought that it would be a wonderful idea to burn mercaptans in a rocket, which wasn't quite as toxic, but caused the test site to become a no-go zone just from the unbearable stench.
As described in Clark's book, ClF3 was discovered first (before WWII actually). But sometime later someone managed to synthesize ClF5 as well, which had slightly better performance as a rocket fuel oxidizer. Although it retained all the other fun properties of ClF3.