[azernik]

Another interesting one I've heard is getting into space, period. It's possible that there are other technological civilizations out there, but all stuck under a few hundred km of ice or on a 2-earth-mass monster where it's impractical to reach orbit.

Earth may only be special in being in a sweet spot between Mars (too small to hold an atmosphere or protect from cosmic radiation, hence no life) and Gliese 832c (with its low-orbit velocity of something like 15km/s, hence much less practical to put stuff in space).

[pratyushc]

> protect from cosmic radiation

That raises another issue of the planet having a magnetic core...

[azernik]

You can also get shielding with a thick enough atmosphere, or being under a solid ice/rock crust. But both of those also make it much harder to reach space.