Space-based telescopes general

[Anonymous No.5894506]

http://www.stsci.edu/institute/atlast

Stumbled on this while researching the future prospects for a career in optical/photonics/laser engineering.

Will NASA just continue shelling out more and more advanced space telescopes or will this just get defunded after JWST's being delayed and massively overbudget?

Also, predictions on near-future advances in this technology general.

[Anonymous No.5894554]

Massive single scopes are passe. Obsolete. We already know how to build a better object: The massively distributed telescope. Make 1000s of them and spread them at least across Earth's orbital path. Use digital processing (which we're supposed to be GREAT at) to combine their observational data streams. That really does give you a telescope about 2 AU in diameter. And why stop there? Distribute 1000s more across the solar system itself. Keeping it within Jupiter's orbit makes a 'scope 10 AU in diameter.

Provided you can keep each small 'scope package to around $1 million, you can deploy 1000 for about $1 billion.

These singular large 'scopes are really old news, bad ideas, and ample evidence that we're not as smart as we think we are.

[Anonymous No.5894598]

No, JWST is a budgeting failure, it should not have cost that much. Also Hubble's end of life cost will almost certainly still be higher that JWST.

ATLAST probably won't happen. Both JWST and Hubble were descoped and are less sensitive as a result.

[Anonymous No.5894607]

>>5894554
>Massive single scopes are passe. Obsolete.
No, no no no no. Optical/ NIR interferometers have huge drawbacks and simply cannot compete with single mirror telescopes in the vast majority of observations. They hare dreadful sensitivity, they have awful duty cycles and simply cannot do most of the same things. They have benefits but they occupy their own niche observationally.

Hundreds of meters is hard in optical NIR interferometry, AU isn't happening any time soon. On that large would require titanic telescopes to have enough photons to see anything at all.
> under a billion
No. A 4 element 60 meter mid infrared (easier) space based interferometer is expected to cost 1 to 2 billion.

Interferometer sound sexy but in optical NIR they don't work well at all.

[Anonymous No.5894630]

>>5894607

Yes, there are drawbacks. With wide distribution and signal processing, these drawbacks become small enough that it's time we asked why we aren't doing system-wide stuff already.

And I didn't say we'd deplay massive scopes by the 1000s. I'm talking about SMALL scope, on the order of 1 meter each. Make thousands of them. Economies of scale. Mass production. Didn't we used to know how to do that?

[Anonymous No.5894661]

>>5894630
>With wide distribution and signal processing
No, optical-ir interferometers use physically combined light, you cannot improve that much with signal processing. The problem with sensitivity is fundamental and unavoidable. Going to longer baselines makes this worse.

You need massive scopes as I said. And no the 1-2 billion dollar one used 2 meter telescopes with a max baseline of 60 m. Economies of scale make things cheaper but you cannot add 250 times more spacecraft and launch vehicles with zero increased cost. Light must be physically combined so if you have 1000 elements you need about half a million recombined beams, there will be no light left at the end. 8 recombined beams is the current max.

[Anonymous No.5894925]

bump

[Anonymous No.5894954]

>>5894661
What this guy said.
All those technicalities aside, all of the uncollected light passing through the 2 AU between your interferometers is vital to the final product. With a scope as economically minimal as proposed above, you'll end up with godly angular resolution but almost no light to resolve.
At least I'm pretty sure this is how it works. Am I wrong?

[Anonymous No.5894982]

>>5894954
No that's correct.

Take current generation interferometers on the ground. The major ones have 200-300 m baselines with usually about 4 1-2 m telescopes. There are so many reflecting surfaces in the whole process that around 99% of the light is lost between telescope. Secondly without adaptive optics they can only integrate for about 100 milliseconds. As a result most can only work up to magnitude 5 or 7 if you're lucky (that's only a little dimer than the human eye can see). This means stars and a few bright AGN and nothing else.

If you go to space you remove some problems (other arise like keeping spacecraft separated to within a few millionths of a meter) but the major one stays the same. If you have too much resolving power you won't see anything because the surface brightness of any object won't be high enough. You cannot just have two tiny telescopes and put them a light year apart. VLBI in radio is restricted to very few objects because few are bight enough.

You also have a tiny field of view.

Interferometers have their advantages but as it stands they cannot compete. Much of astronomy is driven by sensitivity and not resolution, here interferometers are useless.