When do you think we will have a detailed map of an extrasolar planet?

[Tom Mazanec]

By what year do you think we will have a map of an extrasolar planet with a resolution of 1 kilometer?

[antoniseb]

By what year do you think we will have a map of an extrasolar planet with a resolution of 1 kilometer?

Unless some alien species hands it to us before that, I don't think we'll have such a map until we send a probe to that star and orbit that planet, and then wait for the detailed image to be transmitted (somehow) back to us. So, my guess is more than a thousand years from now.

Note that it would be possible to do that imaging from this solar system, but the effort and expense is prohibitive.

[Tom Mazanec]

I am giving an optimistic estimate of when we can have a hypertelescope in my vote of 2025. It is such a good idea that I hope it can be implemented in my lifetime, and I am well into my 50s. Maybe an expansion of Planetary Resources?

[Tom Mazanec]

On second thought, I should have voted for 2050.
Well, maybe I'll be a nonagenarian in a nursing home...or medical technology could advance as fast as I am hoping astronomical technology will.

[antoniseb]

I agree with changing you initial vote. For 2025, we'd have to have already committed funding to the development of the giant optical array in solar orbit. This array would require optical interferomtry on a scale orders of magnitude larger than we've ever been able to demonstrate.

Figure out how large it would need to be to get that resolution on a planet ten light years away... then figure out how many photons per second it would need to collect if that planet was spinning as fast as the Earth. The scale of what you're asking for is more than you imagine.

[WayneFrancis]

On second thought, I should have voted for 2050.
Well, maybe I'll be a nonagenarian in a nursing home...or medical technology could advance as fast as I am hoping astronomical technology will.

Seems pretty optimistic. We can't even do this for Pluto yet forget something that is, at a minimum, over 4 orders of magnitude further away. Think about it. As far as I know the closest terrestrial planet is ~20ly away. That is Gliese 581c and its distance is over 25,000 times further away from the Earth as Pluto. This means roughly we'd receive like 0.00000000002% the amount of light from Gliese as we do from Pluto if we could even block out the star's light seeing it orbits at about .07AU from its parent star. I guess the one saving grace we'd have is Gliese is thought to be tidally locked to the star meaning we could try imagine image it, once every ~13 days, over a very long time to build up enough photons to get an idea of the surface topology ... but then any atmosphere would probably mess this up also.

[Ara Pacis]

I agree with changing you initial vote. For 2025, we'd have to have already committed funding to the development of the giant optical array in solar orbit. This array would require optical interferomtry on a scale orders of magnitude larger than we've ever been able to demonstrate.

Figure out how large it would need to be to get that resolution on a planet ten light years away... then figure out how many photons per second it would need to collect if that planet was spinning as fast as the Earth. The scale of what you're asking for is more than you imagine.

VLBI shouldn't be that hard, should it? We don't need to do it in real time. The data can be saved and sent back when one of the telescopes in solar orbit happens to get close enough to earth or a relay satellite to send a clear data burst. Depending on the orbital periods and intercepts, it could take years.

[antoniseb]

VLBI shouldn't be that hard, should it?...

Just as a reality check here, the two Keck telescopes aren't that far apart, and were built to be used for some kind of optical interferometry together... but they've given up on that after limited success, and now the two telescopes will only work separately. These two telescopes are 80 meters apart, and do not move relative to each other (they aren't floating in space).

Doing interferometry with radio is much easier than with optical.

[calcmandan]

Going by our limitations today, where obtaining such grand resolution on something as close to the moon is not obtainable at best, I don't hold much optimism there. We would need to improve our observational ability to a point where we can see 1m resolution easily on any body in our solar system before the grand notion of seeing an exoplanet.

I said 2050 though (after some reflection, 2050 is not realistic either). I think it'll be possible with excellent funding and improvements in computer systems in another century or so... Provided we haven't destroyed ourselves in the meantime..

[Ara Pacis]

Just as a reality check here, the two Keck telescopes aren't that far apart, and were built to be used for some kind of optical interferometry together... but they've given up on that after limited success, and now the two telescopes will only work separately. These two telescopes are 80 meters apart, and do not move relative to each other (they aren't floating in space).

Is that why, or did it have something to do with burial sites and/or endangered critters affecting the decision to build additional "outrigger telescopes"? Did the adaptive optics and atmosphere affect the ability to use interferometry? Wouldn't a more telescopes each using a larger static reflector in space work better?

[WayneFrancis]

Is that why, or did it have something to do with burial sites and/or endangered critters affecting the decision to build additional "outrigger telescopes"? Did the adaptive optics and atmosphere affect the ability to use interferometry? Wouldn't a more telescopes each using a larger static reflector in space work better?

burial sites? endangered critters? The are on top of Mauna Kea in Hawaii. I know of no burials up on the top of any of the Hawaiian volcanoes and know of even less critters as nothing I know lives up on that slap of volcanic rock.

The issue as I understand it is getting the precision to do interferometry on short wave lengths. The tolerances to get the interference are at least 1,000 times greater because optical light is at the low end of the spectrum 1,000 times shorter. If you can't get 2 telescopes working together adding more scopes won't help the picture at all. This is all based on my basic understanding of interferometry.

[Ara Pacis]

burial sites? endangered critters? The are on top of Mauna Kea in Hawaii. I know of no burials up on the top of any of the Hawaiian volcanoes and know of even less critters as nothing I know lives up on that slap of volcanic rock.

http://www.skyandtelescope.com/news/home/139509093.html

But they [the outrigger telescopes] never made it to the summit, victims of a sociopolitical struggle in Hawaii and NASA's shifting priorities in faraway Washington.
...
[Mauna Kea] is also sacred to the Hawaiian people, and the stark, other-worldly summit — known locally as wao akua ("realm of the gods") is dotted with shrines, altars, and hidden burial grounds. Although professional astronomy is a strong driver of the Big Island's economy, lots of Hawaiians are nonetheless unhappy about having their sacred mountain peppered with gleaming observatory domes.
...
A master plan, approved in 1983, allows for no more than the 13 domes that exist there now.
...
a judge ruled that the expansion ... — and construction of the Keck outriggers in particular — could not go forward until a comprehensive assessment addressed environmental concerns for the entire summit.

http://www.ens-newswire.com/ens/aug2...-08-07-04.html

The summit and cinder cones upon which the observatory facilities are built are part of a unique ecosystem out of which have evolved 11 species of indigenous Hawaiian arthropods found nowhere else in the world, including the Wekiu bug, Nysius wekiuicola, a candidate for federal listing under the Endangered Species Act.

The Wekiu bug, which has a substance like anti-freeze in its blood, lives solely on the high elevation cinder cones of Mauna Kea. Over the past several decades, 90 percent of its range has been destroyed by observatory development.

Now you know.

The issue as I understand it is getting the precision to do interferometry on short wave lengths. The tolerances to get the interference are at least 1,000 times greater because optical light is at the low end of the spectrum 1,000 times shorter. If you can't get 2 telescopes working together adding more scopes won't help the picture at all. This is all based on my basic understanding of interferometry.

From first link

NASA's official position is that the interferometer has completed its primary task of revealing dusty disks surrounding nearby stars.
...
For all its success, the Keck Interferometer has never lived up to its full potential. That's because it lacks a quartet of smaller telescopes, each with a 6-foot (1.8-m) primary mirror, that were to be installed alongside the towering twin domes atop Mauna Kea. These four "outriggers" would have given the interferometer the ability to image small patches of sky with unprecedented resolution — down to 30 micro-arcseconds...sufficient to spot Uranus-size planets circling nearby stars.

Apparently, it does work, did work, completed its mission and similar efforts will continue to work in the future.

[whimsyfree]

Note that it would be possible to do that imaging from this solar system, but the effort and expense is prohibitive.

I don't agree that the deployment of large space based multi-element imaging interferometric array is infeasible over the next 500 years. It's infinitely more feasible than the manned interstellar mission which is constantly discussed in these forums. I think 1km resolution is a bit fanciful so I answered 2500 or later. If the question had been 200km resolution I would have said 2300 or earlier.

[swampyankee]

To throw some numbers at this:
Picking a nearby exoplanet (10 light-years), 1 km resolution is about 10^-14 radians, which would require a interferometric baseline at least 1.22e+14 10¹⁴ wavelengths (you guys all knew that).

No matter how difficult this is, it is going to be orders of magnitude easier than an interstellar probe.

[whimsyfree]

No matter how difficult this is, it is going to be orders of magnitude easier than an interstellar probe.

I'm not sure about that. If you're happy to wait 10,000+ years for your probe to get there the main problem is making a robot that will still function after that amount of time.

[swampyankee]

Really tough to get funding for a science project that would probably outlive the civilization that launched it.

[whimsyfree]

Really tough to get funding for a science project that would probably outlive the civilization that launched it.

True but I think it was reasonable to believe you were referring to technical difficulties rather than political ones. Note that they did spend public money on those pioneer plaques and the voyager golden disc. God some alien is going to get a laugh from those.

[Van Rijn]

I'm not sure about that. If you're happy to wait 10,000+ years for your probe to get there the main problem is making a robot that will still function after that amount of time.

Funny you'd mention that. I've been thinking of starting a thread with that idea, building a 10,000 year robot ship based on current technology. I thought of it when I read about the 10,000 year clock concept:

http://longnow.org/clock/

In that case, they're building a mechanical clock intended to last 10,000 years. Part of the plan is to put the clock in a benign environment, so there won't be excessive wear. Also, they're naturally designing for longevity, with parts with long wear and wide operational margins.

So imagine an equivalent Alpha Centauri craft, perhaps intended as a time capsule for whoever (if anyone) that might be there in 10,000 years. I suspect that simple electronics kept non-functioning for most of the flight, kept near absolute zero (so little molecular migration) in a moderately thick radiation shield could have good chances of survival and could be designed with present technology. I'd expect it to be solar powered as it neared its new sun, woken up, perhaps, by a mechanical clock. My biggest concern would be that it be on an accurate path, so it closely approaches the Alpha Cen system, and how it would adjust flight in the system (conceptually easy, but for a system to be used after that many years, not so easy).

Since it wouldn't require any radical new technology, such a thing might not be too insanely expensive. It might actually be a practical way to send a starship to another star. Just don't expect to be around to see it get there.

[whimsyfree]

Funny you'd mention that. I've been thinking of starting a thread with that idea, building a 10,000 year robot ship based on current technology. I thought of it when I read about the 10,000 year clock concept:

http://longnow.org/clock/

In that case, they're building a mechanical clock intended to last 10,000 years.

An interesting idea but perhaps a little retro. Besides it is a continuously moving mechanism that requires some external energy input. For the probe it might be better to use a completely passive mechanism. An obvious choice is to leave the solar panels extended. When it gets close to a star an electric potential is generated that could kick things off. It might be wiser however to protect the solar panels from space weathering. In this case something like a piston filled with a suitably volatile liquid (neon maybe) could drive the unfurling of the solar panels when the probe is warmed by the light of a nearby star.

My biggest concern would be that it be on an accurate path, so it closely approaches the Alpha Cen system, and how it would adjust flight in the system (conceptually easy, but for a system to be used after that many years, not so easy).

With a good enough astrometry you should be able to aim it well enough to fly by aCen. Solar (stellar) sails can, according to wikipedia, achieve a cruising speed of about 70 km/s with available materials and using a 0.2au solar fly by. I back of envelope about 14,000 years to get to aCen, taking into account the fact it will be only about 3ly away by then. Solar sails can also be used for late course adjustements and deceleration. aCen is good for sail breaking because it has two closish stars.

Since it wouldn't require any radical new technology, such a thing might not be too insanely expensive. It might actually be a practical way to send a starship to another star. Just don't expect to be around to see it get there.

Me neither.

[publiusr]

A solar foci mission might get you some good pictures
More: http://www.tsgc.utexas.edu/archive/design/foci/ http://up-ship.com/blog/?p=9363