Future Optical Space Telescopes - i.e. Hubble 2.0 ect

[redliox]

With the Hubble celebrating it's 25th Anniversary, it seems prudent to talk about a proper successor to it outside of the James Webb Telescope.  Furthermore, since there isn't a solid optical/ultraviolet space telescope planned for the immediate future, putting this thread here versus Space Science seemed a better match.  After all, by the time the Webb is in space numerous concepts that are advanced now may become feasible for "Hubble's grandchildren."

It'll start with a few pointers and let the rest of you add what you will as long as it relates to space telescopes.
1) Launchers
2) Orbits
3) Goals

The most obvious starting pointing are the rockets to haul up the 'scopes.  After all, the Hubble's size was limited by the shuttle's cargo bay.  The SLS is the most obvious candidate for a large scope; with the core about 8.5 meters wide it would be safe to assume a mirror 8 meters wide could be accommodated in a solid piece, larger if folded like Webb.  However, with SLS tied to politics smaller launchers may economical.  A fairing only 6 meters wide may be the generous norm from a future Vulcan, Falcon, or further future rockets.  On the good news, within 20 years time mirrors made out of essentially plastic could be in use, following a path the proposed MOIRE telescope takes...which means a 'scope crammed into perhaps even a 4 meter fairing could unfold into a mirror 20 meters or even wider.  So, long-term, things will depend more on the mass a rocket sends up instead of just the fairing size...which would give future projects more breathing room despite the sardine can-sizes.

The orbit we put a new telescope into will be another factor, and surprisingly more telescopes are using orbits untouched when Hubble was launched.  Obviously there are both Solar and Lunar Lagrange points, but a better example is TESS: a resonance orbit with the moon is going to be utilized, putting it into an elliptical 14 day high orbit that is surprisingly stable.  Personally, I'd suggest simply putting a new large scope into geostationary orbit for someplace close, easy to track, and very easy to remain in contact with.  Perhaps many orbits could work...but the one I'd be against is LEO; too much garbage is building up in short not to mention it's a pain for astronomers to work around dozens of daily eclipses, Earthshine, and excessive wobbling; the latter will become especially important if the 'scope needs heavy accuracy for exoplanets and extremely deep views.

Then there's the goals to prioritize.  Although infrared is the strong suit for the task, optical and ultraviolet light should be utilized for exoplanet study too especially if the scope is large enough to directly resolve an exoplanet.  There is plenty of work to be done with neighboring galaxies (certainly any within at least a 1/2 billion light years).   On top of that, a UV 'scope might be able to study the afterglow of GRBs with detail (if not the speed) SWIFT had.

What further thoughts are there for future space telescopes?

[RotoSequence]

I really, really want to see an eight meter monolithic, as something for SLS to do. I don't think any other telescope can capture as much light as a monolithic design.

[Coastal Ron]

Regarding launchers, why be limited to any single launcher?

So far it appears the assumption is that we must launch the entire space observatory in one launch, and so we are limited by the size and capabilities of a single rocket.  And if that single rocket is unique, and there are no other options should it become unavailable, that's a bad thing.

The obvious solution is to build future space observatories in space.  And by "build" I mean final assemble of course - put all the final piece parts and modules together in LEO or even beyond.  And those pieces should be able to fit on any of the commodity commercial launchers.  No more worrying about the transportation portion of the plan.

We already have some relevant experience building things in space, since we have already built the 72m x 108m x 20m sized, 450mT mass International Space Station using modular components.  And this is a skill-set we need to improve upon if we want to expand humanity out into space.

We need to get out of the Apollo mindset of single launch missions and that every mission starts on Earth.  It's the 21st Century - let's start acting like it...

[Stormbringer]

Have you guys seen the "glitter" telescope?

http://www.techtimes.com/articles/46747/20150416/hubble-space-telescope-successor-will-glitter-find-alien-life.htm

[catdlr]

Have you guys seen the "glitter" telescope?

http://www.techtimes.com/articles/46747/20150416/hubble-space-telescope-successor-will-glitter-find-alien-life.htm

additional articles:

http://www.jpl.nasa.gov/news/news.php?feature=4553

http://www.nasa.gov/content/orbiting-rainbows/#.VTxd2CFViko

[redliox]

Regarding launchers, why be limited to any single launcher?

So far it appears the assumption is that we must launch the entire space observatory in one launch, and so we are limited by the size and capabilities of a single rocket.  And if that single rocket is unique, and there are no other options should it become unavailable, that's a bad thing.

Ever heard the phase short and sweet?  Any engineer will strive for simplicity whenever possible.  Skylab and Saylut launched with a single launcher...the ISS required over two dozen with the average shuttle flight costing half a billion each.  Skylab had a telescope...the ISS doesn't.

The obvious solution is to build future space observatories in space.  And by "build" I mean final assemble of course - put all the final piece parts and modules together in LEO or even beyond.  And those pieces should be able to fit on any of the commodity commercial launchers.  No more worrying about the transportation portion of the plan.

We already have some relevant experience building things in space, since we have already built the 72m x 108m x 20m sized, 450mT mass International Space Station using modular components.  And this is a skill-set we need to improve upon if we want to expand humanity out into space.

We need to get out of the Apollo mindset of single launch missions and that every mission starts on Earth.  It's the 21st Century - let's start acting like it...

Assembling space stations is an idea older than Apollo.  Von Braun wanted to build giant rotating stations and a fleet of Martian orbiters in his original visions...but as brilliant as he was, he would have failed economics.  The SEI initiative of the 1980s was essentially a reiteration of Von Braun's old extensive plans, and it got shot down fast.  Be careful about invoking a future that was imagined in the past.

As far as assembling a telescope in space, it won't be easy...depending on how extensive the assembly.  If you're doing something simple, like docking a mirror module to the propulsion stage, that's not too big a stretch.  If you're talking astronauts or robots individually setting 100 mirror pieces...don't hold your breath.  Space isn't so much a construction yard, but a high flying circus act.

A constructive alternative could be flying a network of small telescope forming an interferometer, there have been numerous proposals for that in NASA and ESA.  They could either be larger individual satellites or a cluster of cubesats...and if one cubesat is lost it would be cheaper to launch a replacement.

[redliox]

Have you guys seen the "glitter" telescope?

http://www.techtimes.com/articles/46747/20150416/hubble-space-telescope-successor-will-glitter-find-alien-life.htm

additional articles:

http://www.jpl.nasa.gov/news/news.php?feature=4553

http://www.nasa.gov/content/orbiting-rainbows/#.VTxd2CFViko

Seems like a stretch but it could be an advanced way of making a telescope.  I wonder how far such a cluster of mirrors could focus...to a nearby satellite or directly to a telescope on Earth?

[randomly]

This is my favorite so far
SLS launch-able, no speculative development, and can observe exoplanet spectrums out to 100 ly with flying occulters.

http://www.stsci.edu/institute/atlast/documents/ATLAST_NASA_ASMCS_Public_Report.pdf

[redliox]

This is my favorite so far
SLS launch-able, no speculative development, and can observe exoplanet spectrums out to 100 ly with flying occulters.

http://www.stsci.edu/institute/atlast/documents/ATLAST_NASA_ASMCS_Public_Report.pdf

Yup!  I remember that, and it sums up what's needed in the near future if it were affordable.  The concept ought to be reviewed and perhaps even improved upon once the SLS is available.

[Jim]

 8 meter monolithic is not going to happen, there is no way of handling such a spacecraft in the US

[IRobot]

What about g-force limits and vibration limits? The Shuttle had a very low acceleration, but most cargo launchers go up to 6-10g.

[RonM]

8 meter monolithic is not going to happen, there is no way of handling such a spacecraft in the US

Good point.

The Hubble main mirror is 2.4 m. Something bigger would be good, so how large of a monolithic mirror could be launched from the US?

[Coastal Ron]

Ever heard the phase short and sweet?  Any engineer will strive for simplicity whenever possible.

OK, but that has nothing to do with how big something can or should be.  Just look around you.

Skylab and Saylut launched with a single launcher...

Yes, and the Wright Brothers could only carry one passenger on their first airplanes.  Are you suggesting we never should have increased the size or complexity of passenger aircraft?

...the ISS required over two dozen with the average shuttle flight costing half a billion each.

There are lessons to be learned, but you don't want to learn the wrong ones.

The goal of Apollo was "landing a man on the Moon and returning him safely to the Earth", and so Skylab used what was available from that specific Moon-oriented architecture.  It was not a space station optimized architecture, nor was it supposed to be a demonstration of why single-launch was better than multiple-launch architectures for building space-based observatories.

As for the ISS, we had the Shuttle, so we had to use it for construction.  But that's not to say we couldn't build another ISS without the Shuttle and spend far less on transportation costs.  So building the ISS with the Shuttle did not prove that a multiple-launch architecture was too expensive, just that it could be expensive if you use the most expensive choice.

Skylab had a telescope...the ISS doesn't.

Why would we need to turn the ISS into an observatory when you already have much better independent observatories in space?

As far as assembling a telescope in space, it won't be easy...depending on how extensive the assembly.  If you're doing something simple, like docking a mirror module to the propulsion stage, that's not too big a stretch.  If you're talking astronauts or robots individually setting 100 mirror pieces...don't hold your breath.

So echoing your first comment, we'd probably start with just assembling modules into larger assemblies.  We have a lot of experience doing that on the ISS, so this is not some theoretical exercise.

Space isn't so much a construction yard, but a high flying circus act.

OK.  But if we don't become competent in building things in space we won't be able to go far in space.  There is only so much you can do with a single launch architecture.

A constructive alternative could be flying a network of small telescope...

There may end up being many solutions we use, depending on the specific need.

[hop]

The Shuttle had a very low acceleration, but most cargo launchers go up to 6-10g.

This is not really correct. Per the users guides, Atlas 5, Ariane 5 and Soyuz all have sustained loads under 5g. Some of the lighter Delta IV configurations go up to 6, but this can be reduced at the expense of performance.

[Jim]

8 meter monolithic is not going to happen, there is no way of handling such a spacecraft in the US

Good point.

The Hubble main mirror is 2.4 m. Something bigger would be good, so how large of a monolithic mirror could be launched from the US?

Some where in the 3's.

[Hanelyp]

I really, really want to see an eight meter monolithic, as something for SLS to do. I don't think any other telescope can capture as much light as a monolithic design.

What light a mirror loses by being segmented could be made up for with a larger diameter, enabled by being segmented.

[Lee Jay]

8 meter monolithic is not going to happen, there is no way of handling such a spacecraft in the US

Then you can't do the big segmented one either.  Even folded, that mirror is about 17m long and almost 8m wide, designed to fit inside an Ares V 10m fairing.

So, you've either got to build the capability to handle payloads (or one payload) of that size, or you have to limit yourself to a smaller scope (segmented of around 9m or monolithic of around 3m).

[dchill]

With all the talk recently by DLR and the Europeans about far side of the moon operations, etc., I figured somebody else would have already brought up the old idea of putting a spinning liquid mirror on the moon.  <<http://en.wikipedia.org/wiki/Liquid_mirror_telescope#Moon-based_liquid_mirror_telescopes>>

Now we just need somebody to figure out how to keep it liquid at moon temps, have its face be reflective (e.g. assuming you can't use mercury), and for bonus points figure out how to filter out the dust and other contamination caused by being on the the surface of the moon from the liquid.  Once we know how to do all that, then all we need to do is figure out how to transport and land on the moon with barrels full of the liquid, a segmented turn table, and all the other equipment...

It probably doesn't need to be on the far side to perform optical astronomy, but if you've already got astronomers sitting around there doing radio astronomy, why not give them some more equipment to keep running? 

[RotoSequence]

8 meter monolithic is not going to happen, there is no way of handling such a spacecraft in the US

Good point.

The Hubble main mirror is 2.4 m. Something bigger would be good, so how large of a monolithic mirror could be launched from the US?

Some where in the 3's.

What are the limiting factors in the US' payload to space logistics? Is there a consensus that Congress will never allocate an SLS launch for a large mirror monolithic space telescope, or is SLS an unsuitable launch vehicle?

[Coastal Ron]

What are the limiting factors in the US' payload to space logistics?

Depends if you are assembling the observatory in space from components lifted in multiple launches, or it has to be folded up in a single launcher.

Is there a consensus that Congress will never allocate an SLS launch for a large mirror monolithic space telescope?

The SLS is supposed to be the government launcher for government payloads that are too large to fit on commercial launchers.  So I think Congress would be thrilled to hear that the SLS is actually needed for a real payload.

However the real question is whether Congress would want to fund a Hubble replacement that would be large enough to need the SLS...