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There has been a lot of talk of NASA putting a Lunar Gateway in a Near Rectilinear Halo orbit around the moon, but I don't actually know how much delta-v it takes to get there. Most delta-v maps I can find have the delta-v for a lunar transfer orbit burn (about 3.2 km/s from Low Earth Orbit) and the delta-v for breaking into Low Lunar Orbit from the transfer burn (about 0.82 km/s), but I don't know how much it takes to go from the transfer orbit to a Near Rectilinear Halo orbit. I assume it takes less that Low Lunar Orbit, but how much less?

uhoh
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ORcoder
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1 Answers1

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The delta-v from LEO to NRHO is 3.95 km/s.

The flight time is 5.33 days with an impulsive departure from LEO at 3.124 km/s and an NRHO capture impulse of 0.829 km/s.

http://newpapyrusmagazine.blogspot.com/2018/06/cis-lunar-gateways-and-advantages-of.html

Marcel Williams
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  • Reading the article you linked, it is surprising to me that the cost to go from NRHO to Low Lunar Orbit is so high (0.73 km/s), since that is not much less than the amount of delta v you’d need to capture into Low Lunar Orbit from a transfer orbit in the first place instead of going to NRHO first. I guess that’s the price we pay for having our stuff in a nearby stable orbit – ORcoder May 17 '20 at 17:22
  • Hmm, it’s weird, the first source listed on that page (https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20150019648.pdf) has a diagram that seems to suggest a 428 m/s capture delta-v, while the second source (https://engineering.purdue.edu/people/kathleen.howell.1/Publications/Conferences/2017_IAA_ZimHowDav.pdf ) claims a capture delta-v of 829m/s as stated in your answer and in the linked article. Given the limitations of Orion’s performance I think 829 m/s seems high but I don’t know how to account for the discrepancy. I think I might email NASA or Tim Dodd or someone – ORcoder May 17 '20 at 17:43
  • (The third source doesn’t discuss delta-v and the fourth source has nice diagrams with delta v labels to various lunar orbits but doesn’t include NRHO) – ORcoder May 17 '20 at 17:54
  • https://engineering.purdue.edu/people/kathleen.howell.1/Publications/Conferences/2017_IAA_ZimHowDav.pdf – Marcel Williams May 19 '20 at 00:37
  • Here's a more direct source to the NRHO delta-v requirements: https://engineering.purdue.edu/people/kathleen.howell.1/Publications/Conferences/2017_IAA_ZimHowDav.pdf – Marcel Williams May 19 '20 at 00:38
  • yeah that's the second source I was talking about. I think it must not be accurate, or else I don't understand what it is trying to say, because Orion's Service Module provides less than 1400 m/s delta-v (math on that here: https://space.stackexchange.com/questions/44177/how-much-delta-v-does-the-orion-spacecraft-have). If it really takes 829 m/s to get in and out of NRHO, then Orion wouldn't be able to get back to Earth. Would it be possible to take less performance to do an Earth Injection Transfer from NRHO than it would take to capture into NRHO? – ORcoder May 19 '20 at 23:47
  • I talked to the author of the aforementioned source, and while that value for NRHO injecton is correct, you can do a more efficient capture with two burns (presumably with one nearest to the moon to take advantage of the Oberth Effect) , which is how Orion can manage to get in and out of the orbit. – ORcoder Jan 31 '21 at 05:42