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In terms of either thrust or delta v, what is the next big thing?

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  • $\begingroup$ That's a very broad question. Are you referring to continuous thrusting, and if so specifically electric propulsion, or only large $\Delta v$ changes? $\endgroup$ – ChrisR Mar 8 '17 at 5:34
  • $\begingroup$ I presume that by large delta v changes you're referring to impulsive burns? If so, I don't really care either way. I'm just looking for what's new in the field. $\endgroup$ – Schlusstein Mar 8 '17 at 15:31
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No.

There is a bunch of incremental research on adapting different ion thrusters and other pre-existing propulsion systems to cubesats. There are some experimental propulsions (especially if you count braking: deorbiting satellites as a kind of propulsion) - electrodynamic, or utilizing trace atmospheric drag - that are tested with aid of cubesats, although not intended as actual practical propulsion for nanosatellites - as normally propulsion is means to get a satellite into position where it performs its actual tasks - scientific or otherwise - these propulsion systems cost too much and leave too little room for equipment for these tasks. Cubesat becomes a test stand, not the actual target "customer" vessel.

The one currently being developed, completely novel propulsion system for cubesats, while interesting, is hardly a breakthrough: Electric Solid Propellant propulsion.

The promise of ESP is bringing fully functional, inexpensive and safe RCS capability - and even inexpensive low-performance main propulsion of performance much higher than typical inexpensive alternatives (cold gas, steam), and cost way lower than high-performance alternatives (ion). On top of moderate cost, the solution is really tiny - a single thruster weighing around 6 gram, leaving a plenty of room and mass for the cubesat's primary functions.

The obvious disadvantage, making it not-breakthrough, is the poor performance: the single RCS thruster can provide delta-V of order of 10cm/s to your typical 1U cubesat, and all ESP thrusters have a very modest 200-230s of specific impulse. That's better than cold gas or the likes, but worse than about all chemical (solid, mono- and bi-propellant), never mind ion propulsions. Still, the material safety meets the stringent requirements for cubesats, and the device simplicity vastly reduces its dry mass comparing to "competitors".

Of course RCS is not a highly-sought feature for cubesats, and the puny delta-V is making it hard to to treat as anything but a gimmick.

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  • $\begingroup$ I'm not necessarily talking about new technologies. Cubesat propulsion systems typically perform much further below theoretical limits than do larger scale systems. Optimization can have some pretty dramatic impacts on propellant mass in higher delta-v missions thanks to the tyranny of the Tsiolkovsky equation. $\endgroup$ – Schlusstein Mar 8 '17 at 15:29
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    $\begingroup$ @Schlusstein: Well, with this available currently, there's very little left in the "next big thing" department. Cubesats have too little electric energy supply to get the best ion engine variants working, the requirements put a complete embargo on all chemical propulsion, nuclear engines are dead in the water across the board, laser propulsion is a domain of femto/picosatellites, and cubesats are deployed into orbits too low to start dreaming about solar sail. $\endgroup$ – SF. Mar 8 '17 at 15:36
  • $\begingroup$ There's some dabbling with magnetic propulsion, but that's more station-keeping than actual propulsion, going into nano-newtons. Possibly some new ion engines, like the colloid thrusters will be ported eventually. And there are constant talks about Em Drive, but even if it's not a total snake oil, there's no way to easily provide the ~300W required for operation, never mind the prototypes don't really fit the cubesat weight limits. $\endgroup$ – SF. Mar 8 '17 at 15:38
  • $\begingroup$ What is the limiting factor on the miniaturization of the best ion propulsion systems? Given that a 12U cubesat should be able to pull at least 200 W with deployable panels, I expect that there's a good amount of room for improvement in the electric propulsion department. $\endgroup$ – Schlusstein Mar 8 '17 at 15:41
  • $\begingroup$ What do you mean by magnetic propulsion? $\endgroup$ – Schlusstein Mar 8 '17 at 15:42

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