The EXoplanetary Circumstellar Environments and Disk Explorer (EXCEDE)
  We present an overview of the EXoplanetary Circumstellar Environments and Disk Explorer (EXCEDE), selected by NASA for technology development and maturation. EXCEDE will study the formation, evolution and architectures of exoplanetary systems, and characterize circumstellar environments into stellar habitable zones. EXCEDE provides contrast-limited scattered-light detection sensitivities ~ 1000x greater than HST or JWST coronagraphs at a much smaller effective inner working angle (IWA), thus enabling the exploration and characterization of exoplanetary circumstellar disks in currently inaccessible domains. EXCEDE will utilize a laboratory demonstrated high-performance Phase Induced Amplitude Apodized Coronagraph (PIAA-C) integrated with a 70 cm diameter unobscured aperture visible light telescope. The EXCEDE PIAA-C will deliver star-to-disk augmented image contrasts of < 10E-8 and a 1.2 L/D IWA or 140 mas with a wavefront control system utilizing a 2000-element MEMS DM and fast steering mirror. EXCEDE will provide 120 mas spatial resolution at 0.4 microns with dust detection sensitivity to levels of a few tens of zodis with two-band imaging polarimetry. EXCEDE is a science-driven technology pathfinder that will advance our understanding of the formation and evolution of exoplanetary systems, placing our solar system in broader astrophysical context, and will demonstrate the high contrast technologies required for larger-scale follow-on and multi-wavelength investigations on the road to finding and characterizing exo-Earths in the years ahead. 
Olivier Guyon, Glenn Schneider, Ruslan Belikov and Domenick J.   Tenerelli
astro-ph.IM