But wait, before you go out to build a moon casino we need to talk about a couple things. One, you really have to figure out how the roulette wheel is going to work in a low gravity environment. Second, we’re going to need you to keep the noise down.
Not, noise noise – the airless environment is pretty good at blocking sounds as it is. But radio noise. The pristine nature of the lunar environment provides the absolute cleanest, purest, silent places in the local solar system for radio astronomy.
Radio observatories dot the world, like the Very Large Array in New Mexico, the Parkes Observatory in Australia, and the FAST telescope in China. These telescopes reveal…well, just about everything about the universe. They tell us about quasars, the most powerful engines in the universe driven by the gravitational energies of supermassive black holes. They tell us about the flow of charged particles in star forming regions. They tell us about the distribution of matter in the largest galaxy clusters in the cosmos. The radio view of the cosmos is nothing short of stunning.
But if you’ve ever visited one of these sites, you’ll find that you have to drop off your electronics – they are interference-free zones, sensitive enough that they can pick up the signal from your cellphone miles away. Human sources of radio emission, of which there are…a lot, make astronomical observations challenging.
It’s not just cell phones, but radio and television broadcasts, aircraft guidance and communication, even GPS signals that all cause interference. To help reduce this, astronomers prefer to build new observatories way out in the middle of nowhere, like the upcoming Square Kilometer Array – the largest radio observatory ever built – which will be distributed across western Australia (a giant desert) and the interior of south Africa (also a giant desert).
But even those remote places aren’t good enough for the holy grail of radio astronomy: a weak signal emitted by neutral hydrogen during the cosmic dark ages, a time before the first stars and galaxies when our universe was less than a hundred million years old. This signal contains precious information about the nature of dark matter and the growth of cosmic structures, but it’s completely swamped by terrestrial radio emission. We essentially have little to no hope of ever detecting this signal with earthbound telescopes.
But the moon gives us another chance. The moon’s rotation is locked; it always keeps once face pointed towards the earth. And that means that it always keeps one face pointed away. The lunar farside is the most radio quiet environment in the nearby solar system, with the body of the moon shielding any observatory from Earthly radio emissions.
And oh yes, there are proposals. Take the Lunar Crater Radio Telescope, a project lead by NASA’s Jet Propulsion Laboratory. The idea is to take a specialized set of rovers and deploy them on the rim of a suitable crater. The rovers would split in half, with one segment anchoring itself on the rim, with the other rappelling down the crater wall carrying a thin wire with it.
Those wires would meet at another lander placed at the center of the crater, which would connect the wires together and deploy a receiver antenna, essentially turning an entire crater into a single radio dish larger than anything we can hope to build on the earth. This wouldn’t be the cleanest or most efficient radio telescope, but it wouldn’t have to be: the farside environment is so radio pristine that it would still have the best shot of measuring the signal from the cosmic dark ages.
Other proposals include the FARSIDE concept, which stands for Farside Array for Radio Science Investigations of the Dark ages and Exoplanets. I don’t know if you’re allowed to use the word farside in the acronym farside, but here we are. Instead of a single mega-dish, the farside concept is to deploy many base station landers and independent rovers that would unspool kilometers of radio antenna wire between them, creating a gigantic network of connected and correlated instruments to give a super-duper-high-resolution image of the dark ages (in addition to other science goals).
Both the Lunar Crater Radio Telescope and the FARSIDE observatory are ambitious to say the least, requiring the development and deployment of many autonomous vehicles, not to mention likely the use of local lunar resources in building the instruments.
Which brings up an interesting conundrum. These observatories need to be built on the lunar farside, otherwise they wouldn’t have their radio-quiet advantage.
But to actually make them work we would need communication relay satellites, large and persistent sources of power, and maybe even a mining operation so we don’t have to launch resources from the earth…hey wait a minute, that looks a lot like industrialization! Large-scale astronomical observatories have a heavy footprint, and developing them would lead to the immediate temptation that we could use all that industry and development for other, less scientific pursuits.
But still, if we did it carefully and with a lot of planning, we could develop the moon with the primary, if not sole, goal of scientific research. We can have all that other stuff as a necessity to get the science done, not, you know, moon casinos.