While the Apollo missions took place on the equator of the Moon, much of the lunar exploration planned for the 2024 Artemis mission will occur in a more challenging environment: the south pole, where sunlight is limited.

Nujoud Fahoum Merancy

During a live Tech Briefs presentation called Artemis: Back to the Moon, a reader had a question for Nujoud Fahoum Merancy, Chief at the Exploration Mission Planning Office in NASA's Johnson Space Center.

"How are the technology drivers specific to the lunar south pole different from the Apollo equatorial missions?"

Read Merancy's edited response below.

Nujoud Fahoum Merancy: First, for propulsion systems, it takes more to get to the south pole than the equator.

One of the other big differences is truly environmental. The Sun is very oblique on the horizon at the south pole. It never gets above 6 degrees over the horizon. If you think about what you've heard about Antarctic exploration, where the summer is fully lit all the time and the winter is dark all the time, that's a lot of what's happening on the south pole of the Moon, with that extreme sun angle. There are craters that never see sunlight, and that's where we believe that there is water ice embedded in those craters.

That also makes for a very challenging technology environment, because we have such extremes on power and thermal. If you park a solar array or your habitat on the very top of a ridge of one of those craters, in certain places, you can get in excess of 90% of the year in sunlight. That's extremely useful when you are using solar arrays. We use batteries during the periods of darkness. One of the challenges there is that we have multiple days of darkness. If you get even a little bit off those extreme ridges, you can have darkness that extends for several days at a time. It's very challenging in this environment, to build our power and thermal systems to handle those extremes.

When astronauts were on the equator for Apollo, that was the side of the Moon that we see all the time. You get two weeks of light and two weeks of darkness there, and they only did mission to the equator during those sun-lit periods. If we were doing that today, we could just take a solar array up there, you could do your whole mission, and then go home again.

With the south-pole exploration, it's a big challenge of light and dark cycles, and where exactly do we put the equipment so we get a lot of sunlight on solar arrays? Maybe we have to drag cables to elements for nighttime. The extreme environmental differences are some of the big challenges driving technology improvements since Apollo.

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