How long would it take for a 12U cubesat on a circular polar orbit with altitude 600 km to fall down to 500 km?

Please, add references/calculations to your answer.

  • $\begingroup$ I don't consider any thrusters. The question is, how long would it be on orbit? $\endgroup$ Commented Feb 25, 2018 at 10:05
  • $\begingroup$ The question is, how long would a 12U cubesat remain on this orbit. I don't carry about maneuvers now $\endgroup$ Commented Feb 25, 2018 at 10:12
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    $\begingroup$ @uhoh - A sun-synchronous orbit does not require an integral number of orbits per day. $\endgroup$ Commented Feb 25, 2018 at 10:46
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    $\begingroup$ @tarlan - it is not generally considered appropriate to try to remind people the question is unanswered after only a couple of hours. If there is no activity for a few days or a week it would probably be okay. $\endgroup$
    – Rory Alsop
    Commented Feb 25, 2018 at 14:43
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    $\begingroup$ @tarlan I don't consider it appropriate at all. No one is required to answer your question. Make it an interesting and well-written question, that helps getting answers. $\endgroup$
    – user10509
    Commented Feb 25, 2018 at 15:22

1 Answer 1


There is no one answer to this question. How long a 12u cubesat will remain in orbit depends on a number of factors, including solar activity, orientation, and mass. Atmospheric density at 600 km varies by well over an order of magnitude over the course of the eleven year solar cycle. Flying with the long axis of the satellite along or across track changes drag by 50%. Since drag acceleration is inversely proportional to mass, a very light 12u cubesat will suffer greater drag acceleration than will a very heavy one.

That said, a 600 to 700 km orbit is on the cusp of violating the 25 year lifespan used by NASA and ESA. If your 12u cubesat flies such that the small face faces the wind and the cubesat mass is over 17 kg, the odds are quite high the spacecraft will remain on orbit for over 25 years.

  • $\begingroup$ Thanks! You said 600 to 700 km. What if 500 to 600? $\endgroup$ Commented Feb 25, 2018 at 11:55

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