  Ground-based observation at frequencies below 30 MHz is hindered by the
ionosphere of the Earth and radio frequency interference. To map the sky at
these low frequencies, we have proposed the Discovering the Sky at the Longest
wavelength mission (DSL, also known as the "Hongmeng" mission, which means
"Primordial Universe" in Chinese) concept, which employs a linear array of
micro-satellites orbiting the Moon. Such an array can be deployed to the lunar
orbit by a single rocket launch, and it can make interferometric observations
achieving good angular resolutions despite the small size of the antennas.
However, it differs from the conventional ground-based interferometer array or
even the previous orbital interferometers in many aspects, new data-processing
methods need to be developed. In this work, we make a series of simulations to
assess the imaging quality and sensitivity of such an array. We start with an
input sky model and a simple orbit model, generate mock interferometric
visibilities, and then reconstruct the sky map. We consider various
observational effects and practical issues, such as the system noise, antenna
response, and Moon blockage. Based on the quality of the recovered image, we
quantify the imaging capability of the array for different satellite numbers
and array configurations. For the first time, we make practical estimates of
the point source sensitivity for such a lunar orbit array, and predict the
expected number of detectable sources for the mission. Depending on the radio
source number distribution which is still very uncertain at these frequencies,
the proposed mission can detect $10^2 \sim 10^4$ sources during its operation.
