From there: Dr. van Belle continues, “Observations of binary star systems let us determine the masses because of their orbital motion around each other, and BFT adds extra value by then directly measuring the radii of those stars. Resolved exoplanet transits is going to be the wicked cool one. We will be able to see the resolved disk of another world as it passes in front of its host star. This sort of thing will be good for further characterization of exoplanets, as well as searches for exomoons. There’s a bunch of other BFT science that isn’t part of the core ‘marquee’ cases – many hundreds of different types of stars that we’ll be able to make pictures of and see how those pictures change over time.”

With geothermal, yes there is a huge reservoir of potential energy but speeding up the extraction of this energy is absolutely a terrible idea long term. I'm not gonna rant here, but look at what happened to Mars (only slightly smaller than earth) when the core cooled and the dynamo shut down.