(plan for space telescopes to find smaller exoplanets)
The Terrestrial Planet Finder (TPF) was a NASA plan for
one or more spacecraft designed to find extra-solar planets.
One version of the plan was for multiple telescopes, possibly on
separate spacecraft to function as an interferometer.
Another was for a single larger telescope, larger than
HST, with a coronagraph to block starlight.
Congress postponed further funding 2007 and NASA
canceled the project in 2011.