My question should have being: "Is it possible to have a stable (minimal Delta-V) Circumlunar trajectory that goes around Earth and the Moon? "

Circumlunar free return trajectory

Lunar Gateway trajectory

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    $\begingroup$ It does not meet the requirements? $\endgroup$ Mar 7, 2023 at 4:25
  • $\begingroup$ @OrganicMarble - I thought the idea was to make for an easier connection between Earth and the Moon (for spacecraft). "Spacecraft launched from Earth would perform a powered flyby of the Moon (delta-v ≈ 180 m/s) followed by a ≈240 m/s delta-v NRHO insertion burn to dock with the Gateway as it approaches the apoapsis point of its orbit." $\endgroup$ Mar 7, 2023 at 11:49
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    $\begingroup$ @TheMatrixEquation-balance with this sort of space stuff you need to think less about location and more about velocity. If the gateway is in a high velocity orbit with respect to the moon, any landers need more fuel to descend and get back up again to dock. The proposed orbit involves landers needing to both burn to achieve injection AND do the landing, and coming back up not just achieve orbit but boost up to earth return. It also means the aborting landing is a problem since the gateway is off back to earth. $\endgroup$ Mar 7, 2023 at 12:14
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    $\begingroup$ As noted in a now gone comment, space.stackexchange.com/a/24018/26356 notes that the placement was driven in part by limitations of Orion, making 'best possible within existing constraints' rather than 'best'. $\endgroup$ Mar 7, 2023 at 12:18
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    $\begingroup$ @TheMatrixEquation-balance that is very much a political/financial question, rather than a physics/engineering one, so not really possible to sensibly answer at this point in 2023. $\endgroup$ Mar 8, 2023 at 8:27

1 Answer 1


Because the Gateway is supposed to stay at the Moon, not return to Earth.


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