Abstract
The Fourier-Kelvin Stellar Interferometer (FKSI) is a structurally connected infrared space interferometer with 0.5 m
diameter telescopes on a 12.5 m baseline, and is passively cooled to ~ 60K. The FKSI operates in the thermal infrared
from 3-8 μm in a nulling (starlight suppressing) mode for the detection and characterization of exoplanets, debris disks,
and extrasolar zodiacal dust levels. The FKSI will have the highest angular resolution of any infrared space instrument
ever made with its nominal resolution of 40 mas at a 5 μm center wavelength. This resolution exceeds that of Spitzer by
a factor of 38 and JWST by a factor of 5. The FKSI mission is conceived as a "probe class" or "mid-sized" strategic
mission that utilizes technology advances from flagship projects like JWST, SIM, Spitzer, and the technology programs
of TPF-I/Darwin. During the past year we began investigating an enhanced version of FKSI with 1-2 m diameter
telescopes, passively cooled to 40K, on a 20-m baseline, with a sunshade giving a ± 45 degree Field-of-Regard. This
enhanced design is capable of detecting and characterizing the atmospheres of many 2 Earth-radius super-Earths and a
few Earth-twins. We will report progress on the design of the enhanced mission concept and current status of the
technologies needed for this mission.
