Range-time backprojection for 3D shape estimation of small space debris

A coherent backprojection based approach is presented for 3D shape estimation of small debris in space. The approach utilizes the fact that space debris is in high-speed spinning motion. Making use of the modulated range envelope and Doppler spreading, a backprojection maps the data into a three-dimensional parameter domain, and the spatial coordinates of scatterers can be extracted to reconstruct 3D shape. In most of recent papers on the imaging of space debris or rotating targets, the rotation from the translational motion is assumed to be neglectable, while in our approach the backprojection is combined with a Fourier transform to deal with the rotation of translational motion and full coherent accumulation can be achieved. The approach is robust in the occurrence of serious profile overlapping and strong noise. Simulations confirm its validity and good performance.