  Radio astronomical observation below 30 MHz is hampered by the refraction and
absorption of the ionosphere, and the radio frequency interference (RFI), so
far high angular resolution sky intensity map is not available. An
interferometer array on lunar orbit provides a perfect observatory in this
frequency band: it is out of the ionosphere and the Moon helps to block the
RFIs from the Earth. The satellites can make observations on the far side of
the Moon and then send back the data on the near side part of the orbit.
However, for such array the traditional imaging algorithm is not applicable:
the field of view is very wide (almost whole sky), and for baselines
distributed on a plane, there is a mirror symmetry between the two sides of the
plane. A further complication is that for each baseline, the Moon blocks part
of the sky, but as the satellites orbit the Moon, both the direction of the
baseline and the blocked sky change, so even imaging algorithms which can deal
with non-coplanar baseline may not work in this case. Here we present an
imaging algorithm based on solving the linear mapping equations relating the
sky intensity to the visibilities. We show that the mirror symmetry can be
broken by the three dimensional baseline distribution generated naturally by
the precession of the orbital plane of the satellites. The algorithm is
applicable and good maps could be reconstructed, even though for each baseline
the sky blocking by the Moon is different. We also investigate how the
map-making is affected by inhomogeneous baseline distributions.
