I am curious on what the simplest possible rocket design that have been proposed which could reach orbit. My first thoughts would be earlier rockets like the Atlas LV-3B, but then I consider the stranger designs by OTRAG, through those don't appear to be confirm to be able to work.

  • $\begingroup$ How many orbits and what type of orbits would you consider to satisfy the terms of your question? $\endgroup$
    – Moo
    Jan 5, 2023 at 21:31
  • $\begingroup$ I don't really have any requirements. Perhaps LEO for more than one orbit? $\endgroup$ Jan 5, 2023 at 21:36
  • $\begingroup$ @Uwe "Nobody did it with only one stage." does not mean that "A rocket with at least two stages is needed." Certainly it's achievable. and as pointed out in answers to Has humanity launched a SSTO ... ever? commercially viable launches come close with Atlas-B being the closest (it "cheats" by dropping spent boosters, but does not need an actual 2nd stage to reach orbit). So the OP's question is valid and answerable because it doesn't ask about what's been done, only what would be simplest if SSTO was a goal. $\endgroup$
    – uhoh
    Jan 6, 2023 at 3:18
  • $\begingroup$ different but relevant: Which launch vehicles are considered SSTO? and one answer to Falcon 9R as SSTO says a Falcon 9 core could do it (Musk quote + someone's simulation). If you had money, that would be "simplest" in that you could do it with out doing the engineering yourself, but in terms of simplest design, we'll have to wait for answers. Probably a whole big string of SRB segments stacked together and a robusified nozzle that lasts long enough. $\endgroup$
    – uhoh
    Jan 6, 2023 at 3:25
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    $\begingroup$ No orbital launch vehicle is really "simple". Making a solid fuel motor capable of orbital launch that doesn't kill the creators in the process or blow up the vehicle isn't "simple". Don't try it at home. Relatively maybe, but untold hours of engineering work went into everything that ever launched a payload into orbit. $\endgroup$ Jan 6, 2023 at 14:40

1 Answer 1


Depending on exactly what you mean by simple, the SS-520 might count (see the later SS-520-5 for a successful launch). No guidance, just point it and let it go and stage for a bit. As far as I know it's still the smallest orbital rocket. Not that small implies simple, but the SS-520 happens to be both.

EDIT: looks like I was incorrect; the second stage also does a one-time re-direction using cold gas thrusters, which requires a full GNC suite. This rocket isn't that simple at all. I'm a liar! Take those upvotes away

  • $\begingroup$ I always wondered how the SS-520 was guided having all its stages powered by solid rocket motors. So even the last stage doesn't need to be guided to inject into orbit? It's just spun up from the beginning and maintains its spin to keep it stable and on track? $\endgroup$ Jan 6, 2023 at 20:43
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    $\begingroup$ @JamesCraft as far as I'm aware, its only control response is that it can replan the ignition time of the upper stages $\endgroup$
    – Erin Anne
    Jan 6, 2023 at 21:09
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    $\begingroup$ @JamesCraft It has 2nd stage nitrogen cold gas thrusters. ("SS-520 Nano satellite launcher and its flight result") $\endgroup$
    – user71659
    Jan 7, 2023 at 5:41

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