NASA is gearing-up in a big way to return to the Moon. As of now, and COVID-19 permitting, the first flight of the new Artemis programme that will take astronauts back to the Moon will be in November 2021, with a Moon landing planned for October 2024.

AArtemis I is planned to be a long-duration (3-4 weeks) un-crewed test flight to the Moon and back, followed by a shorter figure-of-eight crewed Moon flight in Artemis II and then the lunar landing and the first woman on the Moon in Artemis III.

Although there are some fascinating parallels with Apollo, there are also huge differences. The Apollo-Saturn programme featured no less than twenty un-crewed flights before an astronaut flew in an Apollo capsule. In contrast, the entire Orion capsule development will have consisted of just six launches before astronauts fly in it. Furthermore, Orion, unlike Apollo, is designed for long-duration flights.

No Apollo crew were in their capsule for more than 12 days. The longest crewed flight in preparation for Apollo – that of Gemini 7 – lasted under 14 days. In contrast, apart from the Artemis 2 shakedown flight, which is likely to be around ten days duration, no crewed Artemis flight is planned to last for less than a month and, from Artemis VIII, pencilled-in for launch in 2029, flight durations are expected to be two months or longer.

Similarly, Apollo featured a quite giddy rhythm of flights, with six crewed flights – Apollos 7 to 12 – launched in just 13 months in 1968 and 1969, putting extreme stress on launch teams and flight controllers. In contrast, Artemis is expected to have a much more relaxed programme, with a baseline of one just launch per year over its first ten flights.

However, in one way, the public watching the Artemis III Moon landing may find things extremely familiar.

Up to now, the assumption was that, when Artemis III flies, it would take its crew of four into a lunar orbit from which two of the crew, including the first woman on the Moon, would transfer to the lander and descend to the lunar surface somewhere in the region of the South Pole. The crew would explore the lunar surface in typically five moonwalks over a seven day stay, in sharp contrast to the three moonwalks over three days of the last three Apollo crews. Artemis IV would, a year later, land alongside Artemis III and would start the task of building the permanent lunar habitat, using its own lander and the left-behind elements of Artemis III.

However, maybe NASA is having a re-think. Although the landing site(s) for Artemis have not yet been selected, some widely reported remarks from NASA Director, Jim Bridenstine, made on September 14^th, have suggested that he is considering a radically different approach for Artemis III. His suggestion was that the scientific value of the landing could be maximised, not by going to somewhere new – almost certainly to the Lunar South Pole – but, instead, by going somewhere that has already been visited.

Why might you do this? To visit high latitudes on the Moon requires a great deal more fuel than landing at a site near the equator as you have to lift the capsule from an equatorial orbit to one of much greater inclination. That takes a lot of effort and so, to get up towards the poles you must sacrifice payload to be able to carry extra fuel. That is why only Apollos 15 and 17 ventured more than a very modest nine degrees away from the lunar equator. Of the six lunar landings, Apollo 15 holds the record, venturing as far as 26⁰.13N. The only other landing to move significantly away from the lunar equator was Apollo 17, which landed at 20⁰.19N.

With Artemis III launching on the less powerful Block 1 Space Launch System, the payload/latitude equation becomes potentially critical. So, the question facing NASA is: if you have to settle for a site close to the equator for your first Artemis landing while waiting for Artemis IV to be launched on the more powerful Block IB version of the rocket that could reach the lunar South Pole easily, where do you want to go?

The answer that NASA seems to be coming up with is that, if the SLS cannot reach the South Pole, the greatest amount of science would be achieved by going back to somewhere that is already explored, where the astronauts would hit the ground running, already familiar with the area and knowing what are the high-value sites to visit. In other words: land close to one of the Apollo landing sites. At present, this is speculation. In an interesting about turn, Bridenstine seemed to rule out any other landing site than the South Pole in a Press Briefing on September 21^st, in which he said “To be clear, we’re going to the South Pole… There’s no discussion of anything other than that.” The reason for this change may be the fact that the contract for the Lunar Lander has not yet been awarded, with three concepts still competing for the contract and the required $3.2 billion to fund the landing must be passed by Congress by the end of the year if the plan for a 2024 landing is to stay on schedule. So, there are still a lot of unknowns, both in the schedule and the payload capability of Artemis III that mean that a South Pole landing is in no way ruled out at this moment.

After fifty years of analysis of the Apollo moonrocks, many questions have been answered, but others have arisen. Part of the problem is that, with the honourable exception of Jack Schmitt, none of the astronauts were geologists, nor had they received more than basic training in geology. With the gold visor down, their ability to distinguish colour and thus make informed sample choices, was severely compromised – it was noticeable that Jack Schmitt kept his visor up whenever possible.

Despite the well-known problems with the Apollo 11 landing, Pete Conrad showed, with Apollo 12, that pinpoint landings were possible. This allowed NASA to get increasingly ambitious. Apollo 15 landed on a site for which there was not even high-resolution imaging available, making the landing especially risky, although brilliantly executed. Apollo 15’s landing required a much steeper angle of descent than any previous mission as it had fly over the Lunar Apennines to land between Mount Hadley (which stands 1450m above the surrounding plain) and the rather lower Mount Hadley Delta.

The culmination in daring and in piloting skill though was the landing of Apollo 17 in the Taurus-Littrow Valley, that saw Gene Cernan fly the Lunar Module over mountains 2000 metres high, to land neatly in a substantial crater field.

So, if you were unable, for whatever reason, to be able to reach the Lunar South Pole and decided to return to an Apollo landing site, which would you choose?

Apollos 11 and 12 landed in the flattest, most boring terrain that NASA could find. The aim was to avoid risk, with scientific interest a very distant second, although one of the selling points of Apollo 12’s site in Oceanus Procellarum, the possibility that it was crossed by one of the rays from the crater Kepler.

Although the Apollo 14 landing site in the Far Mauro Hills was certainly not as flat as the previous landing sites, it was still a very conservative choice, as the astronauts were limited to walking and still had the short-endurance backpacks. By far the most spectacular landing sites were those of the three heavy, science missions that closed the programme: Apollo 15, alongside the Hadley Rille; Apollo 16, in the Descartes Highlands; and Apollo 17, in the Taurus-Littrow Valley.

If science is the only criterion, it is hard to beat the Hadley Rille. Maybe my memories are coloured by the fact that Apollo 15 represented the first time that NASA processed the TV images to give much better quality and resolution before they were transmitted. Viewing them, as an 11-year-old, the panoramas of Mount Hadley and the stunning views down into the Hadley Rille and the panoramas of the majestic Mount Hadley, the first mountain that astronauts had seen from the surface were so spectacular compared to anything that we had seen previously from the Moon that they were unforgettable. Maybe Mount Hadley did not have the sharp crags and cliffs of mountains on Earth, but its lines were still oh so beautiful.

Certainly, the Apollo 15 landing site had enormous personality compared to the Descartes Highlands of Apollo 16. Of all the Apollo landing sites, only Taurus-Littrow can compete.

With the new space suit design giving the astronauts better mobility and a week-long stay on the Moon allowing for more ambitious exploration, the astronauts could even go down to the floor of the rille itself with its priceless geological treasure trove. There would also be the opportunity to go one better than Dave Scott and Jim Irwin and find the true Genesis Rock. Although sample #15415 – its official designation – was found to be “only” 4.1±0.1 billion years old and thus not a fragment of the original lunar crust, as hoped, there is the chance that there are even older anorthosite rocks in the area.

However, there is an alternative and very political option for the Artemis III landing site. You can certainly argue that there would be huge publicity and emotional value in landing at the Apollo 11 Tranquillity Base to initiate site conservation (hint: if on schedule, the putative Artemis III landing would be potentially just days before the 2024 Presidential Election). It would not be a great target for science, although you might also argue that there is justification in going back to one of the maria to contrast its geology with the much better explored highland sites from later in the Apollo programme.

More than anything, though, you can just imagine the impact of the President announcing that, apart from their science tasks, the Artemis III astronauts would initiate the conservation work to turn Tranquillity Base into a Museum/Heritage Site/Monument/National Park (delete to taste). Certainly, the time will come when future tourists will gaze in wonder at the descent stage of Eagle and the first steps on the lunar surface e, so why not start the conservation of the site with the first landing on our return to the Moon?  The Artemis III astronauts might even re-plant the flag[1].

Jim Bridenstine was hinting that maybe emotion could win-out over hard science for the return to the Moon and that the South Pole can wait for Artemis IV.

Which would you pick for the human race’s return to the Moon: Tranquillity Base, or the Hadley Rille? Or should NASA not settle for anything less than a landing at the South Pole?

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[1] As explained in a previous post, the Apollo 11 flag fell when the astronauts took off to return to Earth. Images from orbit show that only two flagpoles still stand – those of Apollo 12 and Apollo 17 but, the flags themselves, disintegrated long ago and, at best, only a few shreds of material remain.