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Could We Build A Bridge To The Moon?

VO: Noah Baum WRITTEN BY: Caitlin Johnson
Few humans have ever set foot on the moon. But, in the future, lots of us could be living on the lunar surface. But, what if we didn't need to fly a space shuttle to get there? What if the moon and Earth were connected by a futuristic bridge? In this video, we take a look at real-world plans to make travelling to the moon much easier, including a genuine "space elevator" and a sci-fi style retractable highway. But, will the plans ever work? Could we really build a bridge to the moon??

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Could We Build a Bridge to the Moon?

For centuries, mankind dreamed of the moon. And, those dreams were mostly realised in 1969 when Armstrong and Aldrin set foot on its dusty surface. Since then, our sights have slowly but surely turned towards Mars, but that hasn’t stopped a few people from contemplating one day colonising our closest celestial object. But even space launches to the International Space Station are still fraught with danger, and missions to the moon even more so… Which is why some people have suggested a way to mitigate these risks by building a more permanent structure – a bridge to the moon.

For a frame of reference, the moon is an average of 238,900 miles away. The ISS is only 250 miles away, and the building of that is considered one of the greatest technological feats of recent times. For even greater context, the distance to the moon is also almost ten times the circumference of the Earth itself, meaning that a construct capable of bridging between here and there would also (theoretically) be able to wrap itself around the entire planet ten times. The current tallest building in the world, the Burj Khalifa, is only half a mile tall – or 829 metres. So, this moon bridge would need to be the same length as roughly half a million Burj Khalifas stacked on top of each other reaching all the way out into outer space.

But perhaps the greatest hurdle of all isn’t even the length of the bridge itself, but rather that the distance between the Earth and the moon is constantly changing depending on tides and where the moon is in its orbit. It drifts between 225,000 and 252,000 miles, which has the difference alone measuring at 27,000 miles (that’s around 54,000 Burj Khalifas). While in the grand scheme of the cosmos it isn’t a particularly large figure, it clearly makes all the difference in whether our bridge to the moon could ever actually reach its destination.

But there are more problems outside of just how something like that would even be scientifically possible… namely the question of, even if we could build such a structure, who would actually do it? To stick with the Burj Khalifa comparison, this enormous tower had a construction cost of $1.5 billion – a fair price for half a mile of skyscraper. But the bill for our bridge would be (appropriately enough) astronomically expensive. It’d easily become the single most expensive construction project in the history of mankind, and that’s before you take into account that when you finally get to the moon you’d need to build even more things to create a reason to go there at all.

Since we’re increasingly relying on private companies like SpaceX to get us to Mars, perhaps the most likely scenario would be another eccentric billionaire showing up, ready and willing to fund a headline-making (though ludicrously expensive) project. It’s not exactly beyond the realms of possibility, though. One company – Moon Express – has already received permission from the United States government to build outside of Earth’s orbit. Who knows, maybe someone somewhere is already mapping an Earth-to-moon super-highway.

Another company with similar goals to Moon Express is the Obayashi Corporation, a Japan-based business which, in 2012, announced its plan to build an operational space elevator by 2050, or even as early as 2035. A space elevator is essentially a space station built in geostationary orbit, at least 22,000 miles above the Earth’s surface, which is kept tethered to our planet by a huge cable – which, ideally, doubles up as a transport link. In theory, the development of a space elevator is the first step on our journey toward building a similar transportation system to the moon, giving us valuable information for what problems we would face. The Obayashi elevator, if it’s completed, will rise 60,000 miles up in total, but also travel at a speed of 120 miles per hour, making it much slower and arguably safer than a commercial aeroplane. But, some are already trying to trump standard space elevators; notably LiftPort, which is a crowdfunded campaign aiming to build a ‘lunar elevator’ direct to the moon. The project has already raised more than $100,000.

The elephant in the room when it comes to all of these projects, though, is the material. Simply put, there’s no known material on Earth which would be able to reliably endure the (in-part unknown) rigours necessary in order to remain stable in outer space. The structure would be too high up to be properly stabilised by gravity, so would instead be dragged through space at the same speed the Earth rotates at – which is 1,000 miles per hour. Even if the bridge was built entirely out of diamond, it wouldn’t be strong enough to withstand the g-force – though it’d certainly look spectacular. This is part of the reason it’s going to take Obayashi so long to build their elevator, because they’re currently waiting for the development of tech strong enough to suspend a space station in perpetual orbit.

For most engineers and experts, there’s only one material that might be up to the task: carbon nanotubes. The Russian Academy of Scientists in particular have worked to make nanotubes a viable option. They’re lightweight and fifty times stronger than the materials we currently have, but they’re difficult and expensive to produce. Regardless, the likes of Obayashi are holding out hope that nanotubes will one day be mass produced.

The flexibility problem is still an issue, though. More than anything else, our bridge would need to be “bendy” – either curving according to the distance to the moon, or able to lengthen and shorten itself to account for the changing mileage. What’s perhaps even more pressing, though, is that it’s almost certainly impossible to build something that’s permanently fixed to the Earth at one end while simultaneously fixed to the moon – given that the moon, like the Earth, rotates. So, for a permanent bridge, we’d need to find a way to stop the moon rotating by building something strong enough to counteract its spin. It’s not possible, but if it were, it’d cause untold chaos to our Earthly lives. Plus, such a move would see the moon begin to fall towards us, meaning our bridge would also need to be strong enough to hold up the weight of the entire moon. Clearly, having a retractable mechanism of some kind is the most reasonable solution – with advocates arguing that we could have short-range landing craft, or shuttles, to take us down to the actual surface. Which, relatively speaking, makes a lot of sense.

There still remains the bigger question of why we’d want to build this link to the moon, in the first place. But, it would quite literally open up a whole new world of possibilities. Perhaps the bridge would be a useful go-between for mining endeavours, since the moon is rich in resources like gold and platinum. Maybe, it’d become the primary route for anyone looking to relocate for a lunar lifestyle, as part of Earth’s first steps toward colonising other places in the Solar System. Or, a moon bridge could simply see the moon become an off-Earth base, from which pioneering astronauts can more readily launch towards Mars and elsewhere.

Ultimately, a bridge may or may not be the best path to take. While some kind of monumental structure soaring into space feels inevitable in the future, an A-to-B bridge still feels incredibly unlikely. But, say retractable space roads really did become a reality… That kind of tech really would give us the moon.

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