Let's do a back-of-the-envelop calculation: There are three fundamental limitations on the resolution for a telescope - one is the angular resolution (how much it can magnify the image of an object), one is maintaining the mirror's parabolic shape tp withing 1/4 wavelength so the image is sharp, and the third is pointing accuracy (how steady it can be in maintaining its pointing direction). Optical resolution is determined by
where
is the wavelength of light being used and D is the aperture size of the telescope. To resolve an object 1 meter high at a distance of 3 light-years (1 x 10^16 meters, which is the distance to the closest star neighboring the sun) requires a resolution of 10^-16 radians. In visible light (
m) this requires a telescope with a diameter of about 1.22 x 10^9 meters, or about 750,000 miles. That diameter is about 50% larger than the diameter of the moon's orbit about the earth. Will this someday be possible? Perhaps. But you have to build a structure that maintains its shape tp with 1/4 wavelength accuracy across its entire surface. We have a hard enough time doing this with telescopes that are "only" 10 meters across - making something with surface area 10^16 times larger would seem to be an impossible task, especially given the tidal forces that would act across it from the sun and Earth. And pointing it with an accuracy of 10^-16 radians - while moving in orbit and being affected by the gravitational pulls of the sun and planets - would also be impossibly difficult in my opinion. So I have to say no - using a telescope to see details on planets orbiting other stars is not practical at all.