Several news outlets are reporting Energia Rocket and Space Corporation is nearing completion of a new electrical rocket engine using iodine stored as a solid and vaporized as needed. The new propulsion promises to be "10 times cheaper" than current xenon-based alternatives, with much less complex and lighter propellant storage and dispensing system, and obviously much cheaper propellant.

This is all great news, but what is the performance? Isp, thrust, power usage, mass? Also, electrical rocket engine is a very broad classification. What type of engine is it precisely?

In case this information is not available at the time, I'd rather have the question sitting open for a couple months until the information becomes public, than have speculative answers.


1 Answer 1


Actually not only Russia, in USA iodine ion engines are being developed too:

1, 2, 3.

For the russian iodine engine information is more scarce. I found this. It's in russian language, with short english abstact at the end. The paper's content looks similar with USA papers above. The paper is about laboratory testing evaluation, but there is almost no numbers.

Advantages of iodine ion engines, according to the papers (in the russian paper it stated more clearly):

  • more compact propellant storage system (solid iodine 4.9 g/cm3 versus high-pressure xenon)

  • more compact engine feed system (sublimator for iodine versus "multistage pressure reduction system" for xenon)

  • xenon is more scarce and expensive - cost is not so big concern (5k$ per kg), but scarcity limits applications of ion engines for big missions which require tons of propellant. Currently about 20 tonnes of xenon produced per year globally as byproduct of liquid oxygen extraction from the air.

The russian paper also say laboratory testing of iodine ion engine is cheaper than xenon engine (more actual for Russia than for USA)

What are disadvantages of iodine ion engines? Why aren't they in use already?

I couldn't find it. My personal guess that one of the problems is feeding, because a pressure of sublimated iodine should be maintained at constant level. Also long-time reliability (1000s of thrust hours) should be demonstrated - in laboratory an then in space.

So, maybe not the proper answer, but:

Iodine and xenon have similar molar weights and ionization potentials. So, iodine ion engines should have a performance similar with xenon engines.

The information about russian iodine engine is scarce, but I suppose it would have Isp about 2000-3000 s, like xenon engines.


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