  The Astro2010 Decadal Survey recommended a Wide Field Infrared Survey
Telescope (WFIRST) as its top priority for a new large space mission. The
report of the WFIRST-AFTA Science Definition Team (SDT) presents a Design
Reference Mission for WFIRST that employs one of the 2.4-m, Hubble-quality
mirror assemblies recently made available to NASA. The 2.4-m primary mirror
enables a mission with greater sensitivity and higher angular resolution than
the smaller aperture designs previously considered for WFIRST, increasing both
the science return of the primary surveys and the capabilities of WFIRST as a
Guest Observer facility. The option of adding an on-axis, coronagraphic
instrument would enable imaging and spectroscopic studies of planets around
nearby stars. This short article, produced as a companion to the SDT report,
summarizes the key points of the WFIRST-2.4 DRM. It highlights the remarkable
opportunity that the 2.4-m telescope affords for advances in many fields of
astrophysics and cosmology, including dark energy, the demographics and
characterization of exoplanets, the evolution of galaxies and quasars, and the
stellar populations of the Milky Way and its neighbors.
