scibri writes "A few months ago, the secretive National Reconnaissance Office gave NASA two Hubble-sized space telescopes that it didn't want anymore. Now the space agency has to figure out what to do with them, and whether it can afford it. The leading candidate to use one of the telescopes is the the proposed Wide-Field Infrared Space Telescope (WFIRST), which would search for the imprint of dark energy, find exoplanets and study star-forming regions of the Galaxy. The NRO telescope could speed up the mission, but may end up costing more in the long run."
A few issues with re-purposing the NRO satellite: higher launch costs because it's bigger, it can't see as far or as much IR (but
it can see fainter objects, and could be used in planet detection), and the need for a bigger camera.