Say we have a guy orbiting Earth in LEO with no spacesuit (I know, I know), what would be the millisieverts he would be receiving?

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    $\begingroup$ That will depend on where in the orbit he is (Sun side, night side, polar orbit), the state of the solar wind, the time of the year, the phase of the Moon, and probably a bunch of other factors: You should be asking what the range of exposure will be, it won't be a single number... $\endgroup$ Commented Dec 3, 2017 at 0:09
  • $\begingroup$ Between 0 and infinity, depends on how long he stays. I guess you're asking for the dose rate in Sv/h. $\endgroup$
    – asdfex
    Commented Dec 3, 2017 at 18:15
  • $\begingroup$ I would look into charts and information related to the van Allen radiation belts. Although LEO is probably below them, you can probably still find what you're looking for there $\endgroup$
    – Dragongeek
    Commented Dec 3, 2017 at 20:15
  • $\begingroup$ Summary of studies of radiation levels in LEO: wrmiss.org/workshops/sixth/golightly.pdf $\endgroup$
    – Hobbes
    Commented Dec 5, 2017 at 13:41

1 Answer 1


After a lot of reasearch, I've found this NASA page https://srag.jsc.nasa.gov/Publications/TM104782/techmemo.htm where it states that "The integral GCR dose rate in free space is approximately a factor of 2.5 higher at solar minimum than at solar maximum. During solar minimum, the unshielded dose to the blood forming organs (BFO) is approximately 60 rem/year." and "Compared to low inclination orbits, higher inclination orbits are exposed to increased GCR levels as the spacecraft transits the higher latitudes. In the proposed Space Station orbit, the magnetic field provides a factor of 10 reduction in total GCR exposure relative to the free space environment." So according to that site the short answer to my question is: the guy would be roughly receiving an average dose of 0.00685 mSv/h in LEO in low inclination orbits at solar minimum.


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