The Roman Space Telescope (RST, or Nancy Grace Roman Space Telescope, earlier known as WFIRST for Wide Field Infrared Survey Telescope) is a planned near infrared NASA space observatory for dark energy/cosmology and extra-solar planet research, including a coronagraph for exoplanet direct imaging. Plans also include significant surveying for gravitational microlensing transients, e.g., to discover difficult to see astronomical objects such as planets including field planets, brown dwarfs, low mass stars, and compact objects. It will use a surplus National Reconnaissance Office telescope that has the same width mirror as HST (2.4 meters) but a shorter focal length, thus wider FOV. Current plans are to launch in the mid 2020s, for an orbit at L2 for an initial 5-year mission with potential for a second. Instruments:
The original WFIRST proposal (2011-2012) included construction of a new 1.3 meter telescope. While both variants were under consideration, the now-adopted plan was called WFIRST-AFTA (Astrophysics Focused Telescope Assets). WFIRST is essentially a rename of the JDEM (Joint Dark Energy Mission) proposal (of circa 2005-2010), a mission plan superseding various dark energy research proposals, including SNAP (Supernova Acceleration Probe), Destiny (Dark Energy Space Telescope), and ADEPT (Advanced Dark Energy Physics Telescope).