  Several mission concepts are being studied to directly image planets around
nearby stars. It is commonly thought that directly imaging a potentially
habitable exoplanet around a Sun-like star requires space telescopes with
apertures of at least 1m. A notable exception to this is Alpha Centauri (A and
B), which is an extreme outlier among FGKM stars in terms of apparent habitable
zone size: the habitable zones are ~3x wider in apparent size than around any
other FGKM star. This enables a ~30-45cm visible light space telescope equipped
with a modern high performance coronagraph or starshade to resolve the
habitable zone at high contrast and directly image any potentially habitable
planet that may exist in the system. We presents a brief analysis of the
astrophysical and technical challenges involved with direct imaging of Alpha
Centauri with a small telescope and describe two new technologies that address
some of the key technical challenges. In particular, the raw contrast
requirements for such an instrument can be relaxed to 1e-8 if the mission
spends 2 years collecting tens of thousands of images on the same target,
enabling a factor of 500-1000 speckle suppression in post processing using a
new technique called Orbital Difference Imaging (ODI). The raw light leak from
both stars is controllable with a special wavefront control algorithm known as
Multi-Star Wavefront Control (MSWC), which independently suppresses diffraction
and aberrations from both stars using independent modes on the deformable
mirror. We also show an example of a small coronagraphic mission concept to
take advantage of this opportunity.
