More than 50 years after Apollo 17, the last Apollo crewed spaceflight to the Moon, deposited Eugene Cernan and Harrison Schmitt on the lunar surface, and 57 years after Neil Armstrong made one small step for man with Apollo 11, astronauts are on their way back to the Moon.
Spaceflight to the lunar surface has been energised by the potential of the Artemis missions, which aim to use the Moon as a pit stop on a much bolder cause: crewed flights to Mars. First mooted by NASA in 2017, the Artemis programme wants to build a permanent base on the Moon that can act as a gateway to further-flung destinations. And since Artemis 1 took off from Kennedy Space Center in November 2022, the moonshot has helped reignite interest in space exploration.
“It's amazing what our predecessors were able to achieve in the 1960s and 70s,” says Jim Geffre, NASA’s vehicle integration manager on the Orion programme. Orion will carry the Artemis crew into space. “But Artemis is really looking to build off that legacy to be able to go and explore parts of the Moon that was never possible back then.”
Yet Artemis is just one of many projects with the Moon in their vision. In the next decade, commercial, academic and government agencies could launch 235 separate missions to the Moon – multiples more than occurred in the previous decade, according to Euroconsult. Not all of those missions will be crewed – far from it, given the stakes involved. But it’s an indication of how much interest in exploring the lunar surface has revived in recent years.
Sister act
Leading the way is NASA’s Artemis programme, which has the backing of 37 countries acting as signatories to the Artemis accords that govern the peaceful exploration planned for the projects. Named after the twin sister of Apollo in Greek mythology, Artemis aims to land the first woman and next man on the Moon by 2025. But how does the engineering behind Artemis compare with that of its predecessor, the Apollo programme? And what challenges lie ahead for this 21st-century moonshot?
At first glance, the Artemis mission might seem like a significant leap forward from the Apollo era. After all, five decades have passed since the last Apollo mission landed on the Moon. However, as Martin Barstow, professor of space science at the University of Leicester, points out, the core concept remains remarkably similar. “I don’t really see it as being that different to what we did with Apollo,” he says. “It’s a capsule. It’s larger, so it can accommodate more people. But it is basically a capsule with a service module, it will re-enter and have a heat shield, just the same way as Apollo.”
Keeping the same broad concept for the two missions is obvious, says Barstow. It follows the ‘if it ain’t broke, don’t fix it’ approach. “There’s no reason why you should discard it,” he explains. “That technology worked really well.”
Yet there are some key differences between the two missions – particularly when it comes to the engineering of the capsule, and especially the fine details. “In terms of developing Artemis and Orion, we’ve learned a lot of lessons from those earlier explorations – things to do and things to be worried about, like lunar dust and other things,” says Geffre. “The Orion spacecraft looks very similar to the capsules of old; however, that’s mainly an appearance thing and, once you get below the surface, it’s a lot different.”
Evolution, not revolution
The Apollo missions demonstrated the effectiveness of the capsule design for both lunar missions and atmospheric re-entry. That latter element is why the Artemis mission is not much different at first glance from the Apollo mission. “It turns out that the laws of physics haven’t really changed since the 1960s,” says Geffre. “That blunt-body capsule shape is really efficient for safely re-entering Earth’s atmosphere.”
By building upon this foundation, NASA can focus on refining and improving the technology rather than reinventing the wheel. Although the basic concept may be similar, the Artemis programme benefits from decades of technological progress. “I’m sure it will be certainly more up to date,” says Barstow. “Innovations in battery life and electronics mean that these elements are way different to what was first developed in the 1960s and honed in the 1970s.”
“We are taking advantage of many decades of computing advancements and computer and software technology that allows us to automate and make the vehicle more autonomous from Earth than was ever possible in the 1960s,” says Geffre.
That frees up time for the crew to spend on the science behind the mission – Artemis is designed to improve scientific knowledge of space, as well as acting as a proving point and a first step towards Mars. A visual example of that is what astronauts will encounter when they enter the modern-day capsule, compared with what Apollo astronauts saw. Then they’d be confronted with between 400 and 500 switches and levers to control the different systems. The interior today is more like a few dozen, bolstered by a handful of displays, because much of it is automated.
A mission for the era
The fact that little may have changed in the five decades between missions ought not to be too shocking when considered in the context of risk assessment and astronaut safety. The Apollo missions were undertaken in the context of the Cold War space race, where the political imperative to beat the Soviet Union to the Moon often overshadowed safety concerns. And while China – as well as private enterprise – is snapping at the heels of NASA in this latest space race, there’s less urgency to get to the Moon first at all costs.
“Apollo’s tremendous achievement was that a whole lot of development was packed into a short space of time,” says Barstow. But that came with drawbacks. “It was so obviously seat of the pants that there were huge risks involved in that technology. Risks were taken that paid off.”
In contrast, the Artemis programme operates in a different era, with a more cautious approach to progress. “I think the risk appetite of NASA is also more realistic now,” Barstow notes. “People need more certainty. They don’t want to be flying quite so close to the limits of what’s possible.” While Apollo mission craft had just the one flight computer to handle everything, leaving the astronauts at the risk of it failing entirely, those used on the Artemis mission will have four.
Room for more
Engineering also means the journey will be less uncomfortable for the astronauts chosen, says Geffre. “The miniaturisation technologies, lighter and higher-strength materials, all allow us to create more volume inside and more capability for the astronauts – because these missions are more challenging,” he explains.
Evolution in materials has enabled that space to increase, even as more astronauts join the mission. Apollo was largely built of aluminium, with some stainless steel on the outside, says Geffre. “Since that time, we’ve developed higher-strength alloys of aluminium, which are a little bit lighter weight, and allow you to make things either lighter or thinner. We also use titaniums, which are really high strength-to-weight ratio materials.”
But the biggest advancements from an engineering materials perspective have been in the area of composites. Carbon-graphite composites allow stiff, strong structures to be made while keeping weight down – something engineers in the 1960s would have loved to have, but didn’t.
How the capsules and vessels are made has also changed. While 3D printing or additive manufacturing isn’t yet being used at a wide scale within the programme, it is helping with the creation of prototypes that can quickly be tested and learned from to iterate new ideas. “There are amazing computational capabilities with cloud computing and other type of technologies, including software programs to do computer-aided design,” says Geffre. “In the past all that was done on drafting tables and slide rules. It allows the engineers a lot of tools at their fingertips to optimise designs and iterate rapidly.”
That rapidity is key, given NASA wants to launch the next Artemis project next year. But it’s all made possible thanks to the evolved engineering behind Artemis and the opportunities that provides – as well as the inspiration it triggers. “I wasn’t alive during the Apollo programmes, but I love the history and so being able to talk about Apollo and compare what we’re doing is really exciting to me,” says Geffre.
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