The original design of WFIRST (Design Reference Mission 1), studied in 2011-2012, featured a 1.3 m (4 ft 3 in) diameter unobstructed three-mirror anastigmat telescope.  It contained a single instrument, a visible to near-infrared imager/slitless prism spectrometer. In 2012, another possibility emerged: NASA could use a second-hand National Reconnaissance Office telescope to accomplish a mission like the one planned for WFIRST. NRO offered to donate two telescopes, the same size as the Hubble Space Telescope with a wider field of view. This mission concept, called WFIRST-AFTA (Astrophysics Focused Telescope Assets), is being matured by a scientific and technical team; this mission is now the only present NASA plan for the use of the NRO telescopes. The mission will remain in this 'pre-formulation' phase until at least early 2016. The WFIRST-AFTA baseline design now includes a coronagraph to enable the direct imaging of exoplanets.