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Artemis 3 is going to land on the Moon's south pole, on the far side of the Moon. Therefore, before launching the crew to the Moon, NASA must put (a) communication satellite(s) either into lunar orbit or to some Lagrangian point. Are there some more concrete plans on how to maintain communication with Houston from the lunar south pole?

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  • $\begingroup$ There is some potentially relevant information on higher frequency allocations for cis-lunar space (rather than deep space) in answer(s) to Will there be “Near Space” Ka-band allocations for TESS? but I do see that this is more about geometry than frequency allocation. $\endgroup$
    – uhoh
    Jun 15, 2020 at 8:25
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    $\begingroup$ Hmmmm.... wonder how long a cable would be needed to hard-link the station to an antenna on the front face of the Moon? $\endgroup$ Jun 15, 2020 at 12:20

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In the original draw, Artemis 3 would have docked to the "Lunar Gateway" (or a smaller replacement) from where the Lander would be deployed. Lunar Gateway would be on a highly elliptical seven-day moon orbit (Wiki Lunar Gateway, Orbit). Such an orbit would have most of its time an access to the lunar south pole. Artemis 3 on the other side is only scheduled to stay on moon for 6.5 days (Wiki Artemis 3, Mission).

But:

By early 2020, plans for Orion and the HLS to rendezvous with the Gateway were abandoned in favour of a solo demonstration of Orion and HLS, and development of the Gateway independent of the Artemis program.

Source: Wiki Artemis 3, Development

This is just a problem, if someone plans to put the Artemis 3 Orbiter in a complete different orbit.

On the other hand a relay satellite near a Lagrange-Point would not help, it could not see a pole (at least not with a sufficient elevation) and a set of satellites in low-lunar-orbit would have a problem keeping a "stable" orbit (as every object in a low lunar orbit).

..::EDIT::..

For my own curiosity I checked the orbit in STK: Assuming a kelperian Orbit, 3000 km Peri..Periluna?..Periselene?... Pericenter above moons north pole and a 70000 km Apocenter above moons south pole I get an Orbit Period of about 7d 19.5h. Time with no access to the south pole: about 6h.

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  • $\begingroup$ To make it clear: HLS is the crewed lunar lander built by SpaceX for the Artemis program. So if I understand you correctly, through the Orion mothership in polar orbit communication with Houston remains upheld? $\endgroup$ Jun 15, 2020 at 12:46
  • $\begingroup$ At least the "Lunar Gateway" was planned as a "communication hub" (en.wikipedia.org/wiki/Artemis_program#Lunar_Gateway). There is no point in using the A3-Orion-Orbiter instead. (HLS is not necessary SpaceX en.wikipedia.org/wiki/Artemis_program#Human_Landing_System) $\endgroup$
    – CallMeTom
    Jun 15, 2020 at 13:03
  • $\begingroup$ Well, at first they need the Orion because, as you stated, the Gateway will be built after Artemis 3. But if the Orion is above the Moon's north, the crew on the south pole can't talk with Houston either, or did I miss something? $\endgroup$ Jun 15, 2020 at 13:27
  • $\begingroup$ @LoveForChrist accepting too quickly discourages others from posting answers because they have no way of knowing that you will be a more "dynamic" than average accepter. It's your choice of course but... $\endgroup$
    – uhoh
    Jun 15, 2020 at 15:23
  • $\begingroup$ As an answering guy I am total comfortable with waiting a day or three to get the green check mark ;-) ... Back to topic: @LoveForChrist I edited my answer after simulating the orbit with STK. $\endgroup$
    – CallMeTom
    Jun 16, 2020 at 4:52

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