  We have studied the science rationale, goals and requirements for a mission
aimed at using the gravitational lensing from the Sun as a way of achieving
high angular resolution and high signal amplification. We find that such a
mission concept is plagued by several practical problems. Most severe are the
effects due to the plasma in the solar atmosphere which cause refraction and
scattering of the propagating rays. These effects limit the frequencies that
can be observed to those above $\sim$100-200 GHz and moves the optical point
outwards beyond the vacuum value of $\geq$ 550 AU. Density fluctuations in the
inner solar atmosphere will further cause random pathlength differences for
different rays. The corrections for the radiation from the Sun itself will also
be a major challenge at any wavelength used. Given reasonable constraints on
the spacecraft (particularly in terms of size and propulsion) source selection
as well as severe navigational constraints further add to the difficulties for
a potential mission.
