Detecting an Extra-Solar ‘Earth’

[slide_Rules]

I understand that astronomers cannot yet detect extra-solar earth-like planets.

However, I’m finalizing details on a science fiction story (about an astronomer) set 200 years in the future. It assumes regular scientific and human advancement – it’s not dystopian. But there is NO faster than light travel (sorry trekkies).

Anyhow, assume there’s a solar system similar to ours. The system’s “Earth2” is similar in size, composition, & distance from its star as Earth is to the sun. “Earth2” also has a biosphere and atmosphere similar to an Earth – but no intelligent life. Earth2's star is similar to the Sun.
Will we be able to detect “Earth2” and its bio-atmosphere in the near future (~50 years) out to distances of 50 light years? 70 ly? 100 ly?

In the far future of my story (200+ years out), I assume a large space based array-detection system could detect such an Earth2 and its bio-atmosphere out to 50 ly. Is that reasonable? Is it reasonable out to larger distances?

Is there a theoretical limit to how distant an Earth2 can be passively detected?
Could a sufficiently advanced civilization passively ‘map’ life bearing planets within its local tenth of the galaxy? Or a quarter of the galaxy?

 

[russ_watters]

In the far future of my story (200+ years out), I assume a large space based array-detection system could detect such an Earth2 and its bio-atmosphere out to 50 ly. Is that reasonable? Is it reasonable out to larger distances?

Boy, I sure hope they do it sooner than that! Here's a mission NASA has on the drawing-board that I really hope they'll do in my lifetime: http://planetquest.jpl.nasa.gov/TPF-I/tpf-I_what_is.cfm

I'd like to know the answer to The Question!

Is there a theoretical limit to how distant an Earth2 can be passively detected?

No - it is strictly a function of the baseline of the interferometer array.

Could a sufficiently advanced civilization passively ‘map’ life bearing planets within its local tenth of the galaxy? Or a quarter of the galaxy?

Meaning detect a bunch of them? Sure. Again, I really hope that's us in the next 30 years or so.

 

[slide_Rules]

No - it is strictly a function of the baseline of the interferometer array. Meaning detect a bunch of them? Sure. Again, I really hope that's us in the next 30 years or so.

Excellent news and info.
I hope we're there in the next 30 years. I knew about planetquest, but was ignorant of the details and only thought it was looking for big planets.

Thanks.