Even as the price of space flight came down dramatically in the 2030s, the environmental and financial cost of using chemical rockets to escape Earth’s gravity held back human expansion to the moon and beyond. There was also widespread anger that space exploration was becoming a preserve of the ultra-rich, leading to a desire for access to space to be democratised.
A dream, for centuries, had been to build a space elevator to take us from Earth into space without using rockets. But how could it be built, and where? The engineering challenges, along with the political hurdles, were too great. The answer was to flip the idea and build a zip line from the lunar surface to Earth orbit. All you had to do was get from Earth to the end of the line, leap on a solar tram and trundle along the track to the moon.
Rockets were still needed to reach the dangling end of the zip line, but since they didn’t have to totally escape Earth’s gravity, far less fuel was required. Unlike traditional designs for space elevators, the line didn’t need a giant counterweight, so the stress on the cable was far less. The to make this a reality were available, and the political and financial case became viable by the 2040s.
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Once built, people and cargo could be delivered from Earth by rocket to the zip line and then on to the moon, with the total amount of fuel needed to move something from our world to its natural satellite reduced by two-thirds. The resulting drop in price dramatically changed what could be done in space and who could go.
The base for the first lunar zip line was constructed close to the moon’s south pole, on the lunar near side, where several moon bases had been established in the late 2030s to take advantage of the near-constant light at the south pole and the big reserves of frozen water in Shackleton crater.
Unlike the moon bases, which retained ties to private companies and nation states on Earth, the elevator was a shared resource. It was constructed under laws designed by NGOs and the , and equivalent organisations in the major contributing territories (India, Japan, China and the EU).
The zip line connected to the moon via the lunar Lagrange point 1 (L1). These are regions in space where the gravity of the moon and Earth balance out, and fuel isn’t needed to maintain the position of an object. In effect, they are parking lots in space, and thus extremely useful sites for depots and spaceports. The zip line – or Lunar Ladder, MoonWalk or Cheese Stick, as it was variously nicknamed – was simultaneously built from a at L1 and the base on the lunar surface. The was chosen as the material, and thousands of tonnes of it were delivered to L1 for construction.
All you had to do was get from Earth to the end of the zip line, jump on a solar tram and trundle along it to the moon
The enterprise sparked several beneficial developments. Chemical rockets, which provide enough thrust to get off a planet’s surface, were still used to get to low Earth orbit, but after that, ion drives hitched a ride on the elevator and were then used to move around the solar system. These drives generate thrust by accelerating electrically charged atoms through an electric field, and were powered by solar energy. This allowed cheaper, and deeper, exploration of the great beyond.
The earliest suggestion for a space elevator dates to 1895, in a thought experiment devised by Russian space pioneer Konstantin Tsiolkovsky. “Earth is the cradle of humanity,” Tsiolkovsky wrote in 1911, “but mankind cannot stay in the cradle forever.” The first test of such technology occurred in 2018, with the advent of the (Space Tethered Autonomous Robotic Satellite – Miniature Elevator). This took place beside the International Space Station, using a design by researchers at Shizuoka University in Japan. It consisted of two small satellites connected by an 11-metre cable with a crawler that travelled between them.
In the 2030s, when the Artemis missions to the moon began, the Gateway space station was built in lunar orbit, and this became a stepping stone to the L1 depot.
The zip line played a pivotal role in democratising space. Going to the moon for work or leisure became something almost anyone could do if they wanted. Scientific breakthroughs followed from the establishment of a research base at L1, and destructive operations such as mining were moved off-planet. Much of the polluting industrial infrastructure of Earth – especially the server farms that supported computer demand – were moved to the moon where they could be more efficiently powered by solar energy.
But more than that, the People’s Zip became emblematic of the societal change that began in the 2040s, as the influence of the mega-rich waned and cooperative power grew.
Rowan Hooper is 91av‘s podcast editor and the author of How to Spend a Trillion Dollars: The 10 global problems we can actually fix. You can follow him on X @rowhoop
