[X] My Assistant

[tacitus]

A subject which has been fascinating me recently is the nature of interstellar space exploration at some far off point into the future. It would seem to me that even if one day decades or centuries from now interstellar spacecraft (unmanned or manned) become a practical proposition, the most efficient way of exploring the galaxy around us will continue to be bigger and better telescopes in space, on the Moon, on Mars, etc.

While there is no substitute for being on the spot, it will certainly be many centuries before we have the technology and resources to visit planets and fully explore them more than a few light years in any direction from Earth. But we already know, in principle, how to build ginormous space telescopes that can capture the trickle of reflected photons from exoplanets many light years away, and the odds are we will have the ability to do so within decades, not centuries.

It's all very interesting speculation, though since I am but a mere amateur, I have a few questions about the practicalities and limitations of such an enterprise, assuming the funds and technologies are available. Remember, we're not talking about the near future here. Assume we already have a dozen space elevators around the Earth, colonies on the Moon and on Mars, and regular missions to the asteroids, Jupiter, Saturn, and beyond. Perhaps 200, 300, even 400 years hence.

- Is there a point where bigger or sharper scopes won't help resolve further detail in the images of exoplanets?
- At what point will we have to send the telescopes into the outer system beyond the effects of zodiacal light?
- How far will we be able to probe before interstellar gases and dust become a problem?
- Any guesses as to the absolute limit of reliable observations where we can examine the nature of a planet and its atmosphere--i.e. enough to detect signs of life and civilization--(excluding chance events like gravitational lensing)? Is it tens, hundreds, or thousands of light years?
- If there are planets in, say, the Beta Centauri system, how much detail on their surfaces could we potentially resolve. Could we ever see Beta Centauri b as well as we can Mars from Earth through a thousand dollar telescope?

There are some very interesting mission designs already on the drawing board for the decades ahead, but how much further can we go in exploring the galaxy around us before we would have to leave our own solar system to continue the work?

[Guest_PhilCo126_*]

The most amazing project I ever read about is the Exo Earth Imager which is a brainchild of Antoine Labeyrie. It's made up of 10000 mirrors each with a diameter of 3 m which orbit at a Lagrangian point and form a giant sphere with 400 km diameter. At the center of the sphere sits a satellite which processes all images and send data back to Earth

http://www.otherworldslecture.org/bio3.html
http://www.oamp.fr/lise/seminaires/imagesLabeyrieGlasgow.pdf

[nprev]

The most amazing project I ever read about is the Exo Earth Imager...

"Amazing" is a deep understatement, Phil! I love it, but has anyone run a cost estimate (if that's even possible?) The launch costs alone seem truly terrifying...

I'd guess development & deployment at around US$100 billion, which by the time it can launch would be like five Euros...maybe it is feasible!

[tacitus]

"Amazing" is a deep understatement, Phil! I love it, but has anyone run a cost estimate (if that's even possible?) The launch costs alone seem truly terrifying...

I'd guess development & deployment at around US$100 billion, which by the time it can launch would be like five Euros...maybe it is feasible!

In the forseeable future, perhaps such a project is undoable. But what about in 100 years, or 200? Once we've been to every corner of our own solar system, what's left but to explore beyond it? For that we have only two choices--launch ourselves (or, by proxy, unmanned probes) into interstellar space or build bigger telescopes all the better to see with. Which one of these endeavors will be more practical first? I would be very surprised if it's the probes. The return on investment, no matter howdaunting, would be far greater from launching a mega-space telescope that could instantly observe hundreds of worlds than from launching a probe that would take decades to get to one.