New study demonstrates iodine as satellite propellant... in space Scientists are trying to support the boom in miniaturised satellites with the development of a plasma engine using an iodine propellant — rather than the commonly used xenon — for the first time. Launched last November by Chinese space biz Spacety, the propulsion systems developed by French company ThrustMe are meant to offer …
"Why not ThrustMe?
"Because the French have a problem with pronouncing the th, which comes out as z (ze satellite...)"
the 'th' sound in 'the' is different to that in 'thrust'. There are at least two different 'th' sounds in English and there's an example to illustrate the difference 'the theatre'. So the example isn't a good choice.
See https://en.wikipedia.org/wiki/Pronunciation_of_English_%E2%9F%A8th%E2%9F%A9
I have no idea of what problems the French have pronouncing any of them, although wikipedia does mention some.
The two pronunciations of 'th' are the voiced ('than') and unvoiced ('thing') dental fricative. Both are quite rare in European languages and think in languages generally, this is why non-native English speakers often find them hard. Interesting is that they did not occur in ancient Greek, but they do in modern Greek. Both occur in Spanish. Neither occurs in my native language (in either of them in fact).
Oh that reminds me of some "unofficial" bits of chemistry at school back in the 60's :-)
I seem to recall that potassium permanganate and conc sulphuric acid provided interesting results - covered the entire chemistry lab in a layer of fine black fluff some ten minutes before the class was due to start.
Which in turn reminds me fondly of the grinding mill for gunpowder that my friend and I made out of Meccano, an Andrews tin and some marbles. Sealed (small) jar of the powder was ignited electronically using a model railway transformer, two wires and a sliver of tin foil - I sometimes wonder how I survived my childhood!
"I seem to recall that potassium permanganate and conc sulphuric acid provided interesting results - covered the entire chemistry lab in a layer of fine black fluff some ten minutes before the class was due to start."
Our chemistry teacher was also the deputy head, so he used to think big. When he wanted to demonstrate the reaction of sugar and conc sulphuric, he took a bag of the stuff from the lab steward's tea-making kit and tipped a whole bottle of acid on it. Luckily? he did it in a large crystallising dish and there was a fume cupboard nearby to dump it into.
For a fun read about FOOF, here's Derek Lowe, PhD, discussing why he will never work with it.
https://www.science.org/content/blog-post/things-i-won-t-work-dioxygen-difluoride
https://www.science.org/content/blog-post/things-i-won-t-work-dioxygen-difluoride
"I do hope we're not going to discover that dusting iodine over the upper atmosphere might be a bad move"
I suspect we will. Halogens are highly active chemically. However it may not become apparent for some time, making it harder to reverse.
Iodine is thought to be bad for the recovery of the ozone layer but considering it will be used in microscopic amounts in orbits somewhat higher than the ozone layer, it is unlikely to have any significant effect. hopefully.
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwjSydT4taL0AhUi5uAKHYk3C8EQFnoECAcQAw&url=https%3A%2F%2Fwww.sciencedaily.com%2Freleases%2F2020%2F01%2F200113153310.htm&usg=AOvVaw2KcMF5uvbZk_MQxMG6EFED
From a quick Google, it seems like iodine is about $80/kg, while Krypton is only $3 (and Xenon is $850). But I guess if the storage system is much simplified (i.e. lighter) with iodine, that's probably much more significant than the cost of the stuff itself. I guess we'll know soon enough; if there's a significant cost saving, certain companies putting thousands of satellites into orbit are surely going to take note.
Rockets are 100% engineering tradeoffs. For example, liquid hydrogen has more bang than RP-1 (a refined kerosene) but the tanks are huge and need cryo insulation... so first stages use RP-1 because the rocket overall ends up a lot lighter and smaller, and that's important in a first stage.
It's not a cost saving. It's a space & weight saving. Cubesats have a hard size and mass budget. If you exceed it, you're not a cubesat any more, and you don't fit into the standard launcher or the ride-share.
That sort of thought has been considered before. I suggest a read of:
https://library.sciencemadness.org/library/books/ignition.pdf
He covers how at one point dimethyl mercury was considered, that is something you really don't want to deal with. Not ever. Really, not EVER. A world leading specialist in the toxic nature of heavy metals was killed by what seems like a trivial accident:
https://en.wikipedia.org/wiki/Karen_Wetterhahn
there is a Wikipedia page on this topic.
Data is older but indicated Iodine ~$30-35 and borne out by current googling, and a cost for Krypton of ~$290/kg at the same time frame which looks more realistic to me. YMMV
So cost saving on propellant and likely big reduction in thruster weight/volume. Win/Win
All we need now is one with a charged field to ingest orbital debris and a scheme to atomise it for thrust; mk2 tracks down debris to ingest and declutters LEO
Mines the one with the psychoactive substance -->
I would imagine it's also the cost of containing the gases at very high pressure as opposed to the a solid, transporting it to the satellite and "fuelling" it on the launch site. The raw material cost is probably largely irrelevant. Likewise, they are targetting very small sats and the article says the current gas based ion engines don't scale down small enough.
These are low-thrust devices, only used once an object is in (at least) low-earth orbit. You have the cost of the propellant, _and_ its storage tank (significant for xenon), _and_ the cost to get it to LEO in the first place. See slide 9 of the link below; looks as if at best, it'll run you over $1000/kg for that bit.
https://ntrs.nasa.gov/api/citations/20170012517/downloads/20170012517.pdf
So ignoring the storage issues, but adding cost-to-LEO in, you're looking at $1080/kg for iodine; krypton, $1003/kg; xenon, $1850/kg. Also to be considered is exhaust velocity; if one propellant can be expelled at ten times the velocity of another, thereby generating ten times as much thrust per kilogram, that'll slant things in yet another direction.... I know xenon has an exhaust velocity of around 40 km/s; dunno about the others. If they're significantly slower, it'd go a long way to explain why xenon gets the use it does.
Yes and no. The US test was on an object already at low altitude. As a result, most of the bits decayed rapidly, with the last bit coming down 20 months later.
https://en.wikipedia.org/wiki/Operation_Burnt_Frost
You can argue against ASAT tests on a variety of grounds. But if you're going to do them, for $(DEITY)'s sake, do it on an object at low altitude where it won't cause much trouble. Such objects are numerous. There is absolutely no good reason to blow up something at the altitudes of the Russian, Chinese, and Indian tests.
Easier to add extra propellant mass than engineering to increase the velocity - unless you have a very long voyage planned where the amount of the stuff you chuck overboard matters.
Efficiency is just electrical power in vs kinetic energy out - more complex systems to create higher velocities would generally be less efficient.
Iodine's not just space storable, but a room temperature solid that will vaporize easily (184C). Compared liquid and gas containers that have to deal with the stresses of pressurization, an iodine tank could be very light. Just boil a bit off at near-vacuum pressure for the low demand of an ion engine.
And the density! 4.93g/cc is about four times denser than any common liquid or solid propellant, to say nothing of a gas like xenon. The propellant tank would be so light for the delta-V you could cram in it.
Finally, iodine ionizes at a lower energy than xenon, so it's got that advantage.
Cool stuff.
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