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What kind of fuel do electric propulsion spacecraft and satellites use?

Did any of them get electricity from bateries?

An ion engine creates thrust by accelerating ions using electricity. How is that electricity generated? By solar power?

Joe Jobs
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    There may be a limit to the number and frequency of questions a single user asks whose answers can be easily obtained by searching within this site (or Wikipedia) that the community will accept. At some point "What research have you done?" accompanied by substantial down voting will become the response. – uhoh Aug 09 '20 at 02:13
  • it's not so obvious, for non-experts, that spacecrafts are powered by batteries: none ever talks about spacecrafts batteries, everybody always talks about spacecrafts solar panels, if you pay attention to it... – jumpjack Aug 09 '20 at 09:51

2 Answers2

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Batteries don't have nearly enough power to provide for electrical propulsion. Electrical propulsion is generally powered by solar panels or (in speculative designs) nuclear reactors.

Hydrazine is used as a chemical propulsion fuel, not normally for electrical (though it's not fundamentally impossible).

Propellants (not fuel) for electrical propulsion can be a variety of things, but inert gases and high vapor pressure metals seem to be favored.

ikrase
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    With ion engines I know space x uses Krypton while other groups like NASA use xenon – Lonely Fox Aug 08 '20 at 23:51
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    It should be clarified that the issue with batteries isn't enough power, it's that they don't have enough energy density. A lithium-ion battery pack could easily provide enough power, but it'd be exhausted in a matter of minutes, hours at most. The energy requirements are just far beyond what you can store in chemical bonds. If we could build batteries with enough energy density to run an ion thruster, we'd just use the same chemistry to make better chemical rockets. – Christopher James Huff Aug 09 '20 at 00:16
  • The inert gas helium seems not to be favored. – Uwe Aug 09 '20 at 00:35
  • No, though it might be favorable for some types of electrothermal thrusters.

    Actually, such a battery would have nuclear or near-nuclear power capacity... I wish I had a nuclear rechargeable battery.

     – ikrase Aug 09 '20 at 06:08
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    The big disadvantage of batteries is not only that their energy density is very low, but also that it keeps getting lower as you use them! With chemical fuels, once you have used them, you shoot them out the back of your spaceship, but with batteries, you still carry their weight around even when they are empty. (Unless you do it like Rocket Lab, attach them to the outside of your rocket, and throw them away once they are empty.) – Jörg W Mittag Aug 09 '20 at 09:22
  • Is this answer serious?!? "Batteries don't have nearly enough power to provide for electrical propulsion. Electrical propulsion is generally powered by solar panels". Batteries are the onboard source of constant power, which can be way higher than the power provided by solar panels: if you charge a 100Ah battery for 100 hours by a 1A current, then the battery can provide even 1000A... But anyway electrical propulsion is "famous" to use low power for long times, that's why it's a viable solution for long missions. – jumpjack Aug 09 '20 at 09:42
  • @jumpjack It is not possible for constant power from the batteries to be greater than the average power from the solar panels. Peak power can be, for a short duration, but batteries are mostly used to tolerate interruptions in power. Electrical propulsion is actually famously power-hungry, and is not typically run from batteries. The Dawn spacecraft had a 28 V bus (connected to a 35 Ah battery that was never brought below 80% of full charge) for its main supply and a separate ~100 V bus powered from the solar panels for its ion thrusters. – Christopher James Huff Aug 10 '20 at 14:18
  • Dawn's thrusters themselves used up to 2600 W, and at that power level would have drained the battery in ~20 minutes if they were able to operate from it. (https://spaceflight101.com/spacecraft/dawn-spacecraft-mission-overview/) – Christopher James Huff Aug 10 '20 at 14:20
  • @JörgWMittag With Rocket Lab's Electron, you should also keep in mind that the batteries are only used to pump fuel and oxidizer. The vast majority of the power output comes from combustion of those. With ion thrusters, the entire power output comes from the electrical power input. – Christopher James Huff Aug 10 '20 at 14:23
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All spacecrafts get power from batteries, which act as "energy buffer", periodically recharged by solar panels. This allows providing to the onboard electronic a constant power, which may be not possible if the spacecraft is not constantly lit by Sun, like spacecrafts in non-polar orbits.

A battery can also provide an instant power much higher than the one provided by the solar panels: a spacecraft orbiting around Jupiter can collect only low power from Sun, w.r.t. an Earth orbiting spacecraft, but if it collects it into a, say, 100Ah battery, slowly charged by an 1A current for days, then this battery could even provide 1000A of instant current.

jumpjack
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    And then solar power charges bateries which in turn are used to shoot electrons at the xenon atoms? That is how ion propulsion works? – Joe Jobs Aug 09 '20 at 10:00
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    The first sentence contradicts itself, first stating that the batteries are the power source and then correctly stating that they only buffer the power from solar panels. It also inaccurately claims that all spacecraft are powered this way. They're not common, but several spacecraft have used nuclear power sources instead of solar panels. – Christopher James Huff Aug 10 '20 at 13:51