  We consider imaging of fast moving small objects in space, such as low earth
orbit satellites. The imaging system consists of ground based, asynchronous
sources of radiation and several passive receivers above the dense atmosphere.
We use the cross correlation of the received signals to reduce distortions from
ambient medium fluctuations. Imaging with correlations also has the advantage
of not requiring any knowledge about the probing pulse and depends weakly on
the emitter positions. We account for the target's orbital velocity by
introducing the necessary Doppler compensation. We show that over limited
imaging regions, a constant Doppler factor can be used, resulting in an
efficient data structure for the correlations of the recorded signals. We then
investigate and analyze different imaging methods using the cross-correlation
data structure. Specifically, we show that using a generalized two point
migration of the cross correlation data, the top eigenvector of the migrated
data matrix provides superior image resolution compared to the usual
single-point migration scheme. We carry out a theoretical analysis that
illustrates the role of the two point migration methods as well as that of the
inverse aperture in improving resolution. Extensive numerical simulations
support the theoretical results and assess the scope of the imaging
methodology.
