As A Matter Of Fact, It’s All Dark

While the dark side of the moon wasn’t seen by humans until the middle of the 20th century, that side of the moon isn’t always dark, just hidden from view of Earth by a quirk of gravity. The more appropriate name for the other half of the moon is the “far side”, but while it gets just as much sunshine as the near side does it is dark to one thing in particular: man-made radio waves. That, along with the lack of an atmosphere and ionosphere on the moon, makes it a perfect place for a new telescope.

This telescope isn’t like something you’d set up in your back yard, either. It’s more similar to the Aricebo Observatory in Puerto Rico which uses natural topography to help form the telescope. The proposed telescope on the far side of the moon would use a robot to deploy a net along a fairly large crater to act as a parabolic dish, while another robot would suspend the receiver above the crater. The large size is necessary for viewing deep into space, but is also because of the low-frequency radio signals they hope to capture.

Building a dish like this on the moon is sure to be no easy task, especially since remote control on the far side of the moon is difficult for precisely the reasons that make this a good location for a telescope. But with an appropriate amount of funding and some sufficiently autonomous robots it should be possible. Plus, you never know what you’ll find when looking deep into space.

41 thoughts on “As A Matter Of Fact, It’s All Dark

      1. Turns out that for this kind of thing, what you want is an all-sky telescope, so while you can do some processing on site, you really do need to send everything back to Earth. You don’t know, in advance, when “interesting things” might happen that you want to look at. And a lot of radio astronomy requires integrating over long periods of time, to “average out” the noise and detect very small sources.

        1. I just remembered, I have a hard drive somewhere with a bunch of data from Arecibo from ten years ago. It takes up 30 GB. They can schlurp up a lot of bits.

          Maybe somebody out there is calling CQ DX.

        1. The moons surface doesn’t really get peppered with meteors all that often.Something like 3000kg is known to impact the moons 38 million square km surface every year.You’d have to have lottery winning odds that some of that would land on your cable. Then you’d have to win it again that the impact had enough energy to do anything if it didn’t land directly on top of your cable, theres no atmosphere so its not like there would be a blast wave just a shower of rocks and dust, Whatever you put on the moon has to withstand sub zero temperatures and 100+c temperatures so it will probably be buried and have a substantial heat shield and a meteorstrike nearby isn’t going to be hot enough for long enough to do anything.

          Most meteorites are pretty small, a lot of its just a little bigger than dust and the average big one might be 20-30 grams. You’d need 50 kilos travelling at 100 thousand km to make a hole maybe 30 meters wide but between the Sun and Jupiter our part of the solar system just doesn’t have that many objects like this relative to the size of the area.

        2. I’m a fiber technician. If it’s cut I’ll go. If they need a fiber spliced, it’s easier to train me to be an astronaut, than to train an astronaut to splice fiber…

          Just joking friends…..

          1. Having terminated fiber strands into connectors for modems in people’s houses with cutting edge equipment (10 years ago), I’d actually be inclined to agree somewhat unironically.
            It’s like surgery except you’re not getting paid enough to do it, and even the equipment requires babysitting and frequent calibration.

    1. You need a satellite, yes. “Lunar synchronous orbit” is a bit restrictive (depending on how you define ‘lunar synchronous’, I guess). A large enough polar (in the Earth-Moon plane) halo orbit about Earth-Moon L2 works fine.

      NASA’s planned Gateway could act as a relay.

      Otherwise you could always just store-and-forward data if they’re not in view at the same time.

  1. Turns out that people are working on this. For one thing, you really only need to think about low frequencies (<50 MHz), because for higher frequencies, existing telescopes on Earth work better. Earth based telescopes are easier to maintain, repair, and communicate with (running fiber to somewhere in the desert is a lot easier than a optical or RF link to the Moon).
    The problem with low frequencies on Earth is that the ionosphere blocks the signals, and of course, there's lots of RFI.

    At low frequencies, you don't need a big dish like Arecibo or FAST. Instead, you want it to look more like LWA ( or MWA ( or LOFAR (

    There's a proposed mission to put a 10km radio telescope with 128 antennas on the far side of the Moon, called FARSIDE, oddly enough.

    Shorter white paper:

    1. Being able to observe spectrum that we were never able to observe from Earth would be great. I can certainly imagine why that would be the first priority if building a radio telescope on the moon. Don’t forget though, even at frequencies to which our atmosphere is transparent an antenna on the far side of the moon still has the advantage of being completely shielded from terrestrial interference.

  2. The word ‘dark’ didn’t originally mean an absence of light, it simply meant ‘hidden’. We still sometimes use it this way even today. One example is the ‘dark web’ consisting of web sites that are hidden from normal browsers. So when people first spoke about ‘the dark side of the Moon’ they simply meant the hidden side.

  3. “ Building a dish like this on the moon is sure to be no easy task, especially since remote control on the far side of the moon is difficult for precisely the reasons that make this a good location for a telescope. ”
    Oh, come on. Based on the quality of woodworking hacks we see here, there must be a way to install it front the wrong side or something…

  4. re: punkdigerati remark. “Isn’t that a problem for the dish itself as well?”

    Don’t forget about the “pitchback” capabilities of a net.

    Going to try to linking a comment in this page formatting, one last frigging time.

  5. While we’re there, fetch two more craters a few km apart, put oversized Roombas inside and let them clean it up (crushing debris, redepositing and leveling it), bake with some lasers. drop a coat or two of reflective crap, polish it up. Dig a well in the center for focus point while building construction to hold secondary mirror … decade or two later … wait for Earth eclipse and see what we can see with those big eyes.

  6. Somehow this little gem seems appropriate here. No idea about any sort of history, origins, etc — can’t find any info whatsoever on song or band, TBH. Pandora fed it to me randomly one afternoon. Have to say it’s hilariously cute. It sounds kind of like a story Calvin (of Bill Watterson’s imagination) would tell his Dad as to why he wasn’t in school that day, when he was really careening through the woods with Hobbes in his little red wagon… ;)

    The Bluetones — “The King of Outer Space”

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