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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

TheMatrix Equation-balance
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    It does not meet the requirements? – Organic Marble Mar 07 '23 at 04:25
  • @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." – TheMatrix Equation-balance Mar 07 '23 at 11:49
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    @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. – GremlinWranger Mar 07 '23 at 12:14
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    As noted in a now gone comment, https://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'. – GremlinWranger Mar 07 '23 at 12:18
  • @GremlinWranger - If Starship replaces Orion, will they rethink the orbit for "The Gateway" ? – TheMatrix Equation-balance Mar 07 '23 at 15:57
  • Look, you say in the reopen "My question should have been...". So, change the title @TheMatrixEquation-balance – Starship - On Strike Mar 07 '23 at 20:23
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    @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. – GremlinWranger Mar 08 '23 at 08:27

1 Answers1

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

Jörg W Mittag
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