How big is big enough? Shouldn't we built something like the "Overwhelmingly Large Telescope" in space?
Also, what is the max angular resolving power of interferometric telescopes? I mean how large can they be before they are hindered by their size?
Anyone here make their own Astronomical Interferometer?
>How big is big enough?
The size of your aperture largely dictates your maximum resolution. The larger the aperture, the better the resolving power. Thus, there is never "big enough", just "how big can we get away with?".
>Shouldn't we built something like the "Overwhelmingly Large Telescope" in space?
Yes, that would be nice. However Hubble pretty much pushed the envelope of what can be lifted into space. It turns out it's really hard to put a huge piece of high precision equipment on a rocket and blast it into space.
> Anyone here make their own Astronomical Interferometer?
Nope.
Put it together in space then?
Why was the overwhelmingly large telescope cancelled?
This has been proposed, but I can't remember why it hasn't been done. I think it has something to do with the amount of resources to precisely align mirrors in LEO is cost prohibitive.
What I can say is that if you want to build a segmented telescope in space, why limit yourself to a single collection of mirrors? If it is true that the larger the aperture, the better the telescope, then one could envision an array of simple telescopes flying in formation to build a VERY large array (think about the VLA in NM), with VERY good resolving power. There are currently designs for telescopes such as these, though none have been built yet.
Going a step further, counter-intuitively it has been suggested that dispersing a cloud of scatterers in front of a telescope could replace lenses to a large degree. The idea is thus: use lasers to optically tweezer dust/beads/scatterers into a particular formation, point your telescope at something and measure the signal, then apply compressive sensing strategies to recover the original signal. The scatterers serve to modulate the signal in such a way that every measurement gives you information about everything you can see, in contrast to something like a camera that reserves one pixel to measure light coming from only one part of the scene. Some fancy math later and you get high quality images, sometimes with fewer measurements than would be otherwise necessary.
>Thus, there is never "big enough", just "how big can we get away with?".
Incorrect. See chart. There are telescopes planned for that limit and some cancelled.
>what can be lifted into space.
These things are not one piece, do you know what a Astronomical Interferometer is? It is like those radio telescope arrays you see with all the dishes only these are optical instead, with a few other differences. They are sectional. It'd be like putting 2000+ Hubbles in space.
Also Hubble wasn't the heaviest, "Compton Gamma Ray Observatory" was heavier by 5.75 tons. Not only that but Saturn V rockets can lift 155 tons while Hubble was only 12.25 tons.
>I can't remember why it hasn't been done.
Cost and length of time needed to do it.
All god damn day, Veeky Forums has been removing images when I post. wtf
Optical interferometric telescopy is insanely difficult compared to radio, because we do not have any technology capable of recording the phase of optical-wavelength radiation like we can for radio.
This means you have to combine, with nanometer precision in the precise path length, the original light rays from your telescope apertures at your detector
You mean like all the telescopes in the OP image that use that very method.
The bigger a telescope you make and put into space, the more often you're going to be servicing it because of micro-meteors and space junk fucking up it up because it has more surface area.
Plus, there's the problem of actually getting it into space, or building it in space. Both of those are problems for large objects.
>problems
>problems
>problems
How much of a problem is it for you to get out of bed in the morning?
Oh, sorry; I was confusing it with long-baseline sparse optical interferometers like VLTI, of which there are very few.
Doesn't matter OP, the NRO (national recon office) has telescopes that are at least 40-50 years ahead of what we have currently in space, remember that one telescope that broke and the NRO non chalantly gave nasa what they considered an out dated telescope from the 70's, damn scope performed better than the one that broke
To build something the size of the ISS took multiple countries and tens of billions of dollars, as well as 2 decades.
Let that sink in, and you'll see why an oppressively large telescope in space would be impractical.
the ISS was pork and only took so long/cost so much because it was launched on the most expensive vehicle ever built
Meanwhile SpaceX has come along and is demonstrating launch doesn't have to be so expensive, nor expendable.
Once they produce their BFR, I expect lots of shit will be designed to be built to launch atop it.
>Shouldn't we built something like the "Overwhelmingly Large Telescope" in space?
Generally a telescope in space is about a hundred times more expensive than the same size of telescope on the ground. No one can afford that. Even if they could the technology doesn't exist to build something that large and have it be optically stable.
Interferometers also are very niche. Unlike radio interferometers they aren't very good. Because most of the light is lost before the recombiner and atmosphere they must take extremely short exposures. Optical interferometers barely only recently beat the magnitude limit of the eye. They're not sensitive at all. For this reason and others interferometers aren't going to replace monolithic telescopes any time soon.
The technology doesn't exist to do it in space either at optical wavelengths.
The NRO telescopes are not any more advanced than HST. They just have wider fields. They are different, not particularly better.
>its not a moon
It's a moon with the overwhelmingly large telescope
(please make it happen 2080. I want to see exo planets)
Whenever we can master manipulating gravitational lensing and can make telescopes that have the equivalent of a planet sized mirror, then it will be big enough.
Because it overwhelmed them
>Also Hubble wasn't the heaviest, "Compton Gamma Ray Observatory" was heavier by 5.75 tons. Not only that but Saturn V rockets can lift 155 tons while Hubble was only 12.25 tons.
The problem isn't raw weight but the part of the quoted post that you omitted:
>a huge piece of high precision equipment
even if you have the thrust to lift it that doesn't mean you can lift it without breaking it
So, you also omitted the part about lifting pieces instead of everything, which negates your post entire.
How do you think this shit works anyway? If we went by your logic, nothing at all would be lifted to space because it would all need to be lifted in one piece and would be destroyed in the process.
That would be awesome.
lol literally
>Also, what is the max angular resolving power of interferometric telescopes?
Well, this isn't to any proper scale and I can't find stuff online. I'd estimate it is close to 100m, like 120m-150m max probably.
IKR? Veeky Forums is so negative and defeatist when it comes to engineering problems. "You just can't do it" nobody ever puts forward a solution.
where's the new chinese one ?
It's a radio telescope.
See the OP's image and that arc near the bottom that is the divider between white and grey? That's the 305m one in this image. It is also a radio telescope like the Chinese one.
Daily reminder: NROL satellites have dishes with diameters of 100m
Radio antennas, not optical telescopes.