I’ve seen talk of using the moon or even telescopes all over the world collectively work as a single telescope.
In: Planetary Science
We have two eyes. Amd if you close each eye, you’ll notice that they give *slightly* different pictures.
By combining these pictures, we can get a composite image that contains a lot more information. In our case, the differences between what each eye sees allows us to gauge distance.
Same deal with telescopes. By combining the images that each telescope sees, we can see things that each individual telescope on its own cannot.
you need a special type of telescope that measures the wave length and phase of the light as it captures it.
you record the exact wave length and phase and time and exact position at each telescope and you send it all to a supercomputer. the supercomputer calculates how those waves of light would have interfered with each other. Lenses basicaly do the same thing, where the final output is effectivly the interference between the edges of the lense. so your supercomputer essencially calculates what the image taken from a camera would look like if it some how had a lense the diameter of your telescope array.
there are a few downsides to this, mainly huge processing overhead and the need for exact wave properties, position, and time, but also that while the resolution is what a bigger lense would give you, the brightness is limited by the individual telescopes, so you can see more detail, but you cant see any details that were too dim for an individual telescope. VS something like JWST which has a physically bigger lense (ok mirror) and CAN see dimmer things, even if its resolution isnt better than hubble. (it also has a bigger field of view so there is that too)
There are many approaches to this, but you see it most in radio telescopes. to collect more energy you need a big device, and so installations like the VLA in New Mexico connect a bunch of antennas together. By adjusting the timing between the dishes you can point them mor precisely than the mechanical pointing.
One reason to have a telescope on Earth and the Moon is that you get stereo vision, like you have with your eyes, at much longer distances. This allows you to see only things that are the right distance. This could be very helpful for work like mapping the asteroid belt.
That’s part of my day job. This is done with radio telescopes using a method called interferometry. The Event Horizon Telescope is really a set of radio telescopes spread around the world. Radio waves are received from a distant source (in this case a black hole at the center of a galaxy) by telescopes around the world. The signals are recorded on very high speed disk drives, mailed to a central location where there’s a computer called a correlator. The individual waveforms of the different signals are aligned with each other to less than a billionth of a second so that the very slight time difference between them can be seen. This allows a curious form of stereo vision to produce an image with very high resolution, like seeing a dime on the moon.
Light is a wave. Waves don’t just move in neat straight lines, and because of this you can’t take a wave and focus it down to a single point. The best you can manage is a hazy blob. This isn’t the fault of bad lenses – this is a fundamental limitation caused by waves.
What a lens does, really, is allow us to compare the wave in different places. It takes the wave from all across it and sends the wave to the same spot where it can be measured. The farther apart the waves can be collected, the better our data can be. A bigger lens, or a smaller wave, can both shrink our blob. Making a lens miles across is difficult, though. Since we really just need two measurements, one from each end of the lens, and not the whole lens, we can cheat a bit. We *can* just use “two parts of the same lens” that are really far apart, and not worry about any of the lens between them. Two “separate” telescopes that act like two parts of one lens. To do this you need to somehow take the waves from both, and transport that information to the same place to compare and measure it. This is the hard part. With radio telescopes it isn’t too bad, we can cram the signal into a wire and run the wire between the two. With visual telescopes the frequency is too high to do that, so we have to get really creative with transporting the light long distances but not destroying the information it contains.
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