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Quantum astronomy could create telescopes hundreds of kilometers wide

scientificamerican.com

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Re: Quantum astronomy could create telescopes hundreds of kilometers wide

#11

Post by _Microft »

Cthulhu_ wrote: post #10
tener wrote: post #9

I sincerely hope that thanks to SpaceX the cost of launching telescopes to space will become small enough to allow multiple space-based telescopes (and radio telescopes). We are obviously some ways from that, but not that far away that we cannot start planning for when it happens.

Yeah that would be cool, the Hubble telescope has been massively successful but I would have thought there would be much more projects like that. The James Webb one will be next, but I feel like that one's really risky; they took years to develop and build it, and it's going out to a point of space where it's infeasible to send someone up there to fix it if there is a problem. A ring of radio telescopes in high orbit…

I like the ideas of "solar gravitational lensing telescopes" and "lunar crater radio telescopes". The former would place a telescope extremely far from the sun and use its gravitational lensing effect, the latter would turn a crater on the moon into a giant radio dish. Here is a link for the latter.

https://www.nasa.gov/directorates/spacetech/niac/2020_Phase_...

Re: Quantum astronomy could create telescopes hundreds of kilometers wide

#12

Post by phkx »

I remember how, as a physics student, I was pretty amazed to find that a CD I had lying around created inference rings from the sun shining on it and that I could quite accurately calculate the spacing of the track on the disk. I considered the sun to be a thermal light source - something that should not result in any interference. My conclusion at the time was, that the I was looking at single-photon interference and that the 'lateral coherence length' of the photons coming from the sun must be large. I didn't follow up on this, I'm ashamed to say. But it must me the prerequisite for the attempt to increase the effective aperture of the telescopes.

Another thought that came to me - we already know of a technique to store phase information from coherent sources for practically indefinitely, which is holography. Can anyone tell whether that would be an option for the use case?

edit: I should have spent a little more thought on this comment, but I mostly wanted to get it out of my head and maybe have others pick up on it. The issue with holography is, that the image is created by interference of a reference beam and the reflections from an object. Here, we don't want to image an object, but the light source itself. Maybe we can learn something about the light source when we have multiple holograms created with reference objects...

Re: Quantum astronomy could create telescopes hundreds of kilometers wide

#13

Post by lou1306 »

tener wrote: post #9

I sincerely hope that thanks to SpaceX the cost of launching telescopes to space will become small enough to allow multiple space-based telescopes (and radio telescopes). We are obviously some ways from that, but not that far away that we cannot start planning for when it happens.

Indeed, lower satellite costs open up lots of possibilities. Another project is LISA [0], a gravitational wave observatory made of 3 heliocentric satellites. Pretty wild idea.

[0]: https://en.m.wikipedia.org/wiki/Laser_Interferometer_Space_A...

Re: Quantum astronomy could create telescopes hundreds of kilometers wide

#14

Post by _Microft »

blurbleblurble wrote: post #3
gmkiv wrote: post #2

I shudder to think of the difficulty in maintaining phase coherence at optical wavelengths for the baselines they mention in this article.

The perseverance of scientific obsession must not be underestimated.

It is also amazing how the right amount of curiosity, ingenuity and spirit can create opportunity for insight.

Re: Quantum astronomy could create telescopes hundreds of kilometers wide

#15

Post by kwyjobojoe »

tener wrote: post #9

I sincerely hope that thanks to SpaceX the cost of launching telescopes to space will become small enough to allow multiple space-based telescopes (and radio telescopes). We are obviously some ways from that, but not that far away that we cannot start planning for when it happens.

Yeah would be nice after they had ruined ground based telescopes for the whole planet.

Re: Quantum astronomy could create telescopes hundreds of kilometers wide

#16

Post by chopin »

phkx wrote: post #12

I remember how, as a physics student, I was pretty amazed to find that a CD I had lying around created inference rings from the sun shining on it and that I could quite accurately calculate the spacing of the track on the disk. I considered the sun to be a thermal light source - something that should not result in any interference. My conclusion at the time was, that the I was looking at single-photon interference an…

IIRC, thermal light sources have a coherence length of about 10µm. Otherwise reflection holograms wouldn't work when viewed in a thermal light source.

Also: https://en.wikipedia.org/wiki/Thin-film_interference

Re: Quantum astronomy could create telescopes hundreds of kilometers wide

#17

Post by macspoofing »

tener wrote: post #9

I sincerely hope that thanks to SpaceX the cost of launching telescopes to space will become small enough to allow multiple space-based telescopes (and radio telescopes). We are obviously some ways from that, but not that far away that we cannot start planning for when it happens.

>I sincerely hope that thanks to SpaceX the cost of launching telescopes to space will become small enough to allow multiple space-based telescopes (and radio telescopes).

I think people have unreasonable expectations as to what SpaceX can do. I'm sure there are efficiencies to squeeze out of the business, but it's largely from the ops, and infrastructure around the rocket, not the rocket design itself ... design that has not changed significantly in 50 years.

Rockets themselves are as simple as you can get. It's fuel and exhaust and cargo . That's it. Reusability is fraught with issues and no guarantees it's cost effective (maintenance is expensive, reliability suffers, and decreased cargo/revenue due to needing to carry extra fuel for return). But even if reusability pans out, you're not going to get one (or more) orders of magnitude reduction in launch costs from where we are today. You'll get a few percentage points, maybe a few tens of percentage points and that's it.

Re: Quantum astronomy could create telescopes hundreds of kilometers wide

#18

Post by corporateshil1 »

kwyjobojoe wrote: post #15
tener wrote: post #9

I sincerely hope that thanks to SpaceX the cost of launching telescopes to space will become small enough to allow multiple space-based telescopes (and radio telescopes). We are obviously some ways from that, but not that far away that we cannot start planning for when it happens.

Yeah would be nice after they had ruined ground based telescopes for the whole planet.

Mhm, now we get to hear how some great future philanthropists donate/launch telescopes for society, making them forever great in mankinds eyes. 'cus some entitled folks had to leave a legacy of trash in our orbit since they can't leave anything useful.

Re: Quantum astronomy could create telescopes hundreds of kilometers wide

#19

Post by nitrogen »

macspoofing wrote: post #17
tener wrote: post #9

I sincerely hope that thanks to SpaceX the cost of launching telescopes to space will become small enough to allow multiple space-based telescopes (and radio telescopes). We are obviously some ways from that, but not that far away that we cannot start planning for when it happens.

>I sincerely hope that thanks to SpaceX the cost of launching telescopes to space will become small enough to allow multiple space-based telescopes (and radio telescopes). I think people have unreasonable expectations as to what SpaceX can do. I'm sure there are efficiencies to squeeze out of the business, but it's largely from the ops, and infrastructure around the rocket, not the rocket design itself ... design tha…

Using the same rocket ten times instead of once is an order of magnitude improvement. Why shouldn't it be possible to do even better than that?

Re: Quantum astronomy could create telescopes hundreds of kilometers wide

#20

Post by ordu »

macspoofing wrote: post #17
tener wrote: post #9

I sincerely hope that thanks to SpaceX the cost of launching telescopes to space will become small enough to allow multiple space-based telescopes (and radio telescopes). We are obviously some ways from that, but not that far away that we cannot start planning for when it happens.

>I sincerely hope that thanks to SpaceX the cost of launching telescopes to space will become small enough to allow multiple space-based telescopes (and radio telescopes). I think people have unreasonable expectations as to what SpaceX can do. I'm sure there are efficiencies to squeeze out of the business, but it's largely from the ops, and infrastructure around the rocket, not the rocket design itself ... design tha…

Oh, we are to get an order of magnitude of cost reduction per kg on an orbit. There are attempts to measure it: https://everydayastronaut.com/raptor-engine/
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