Simulations of space VLBI

The paper concentrates on the results from space VLBI simulations undertaken during the past four years, beginning with a study of the imaging potential of the proposed medium-term mission QUASAT, and continuing with the Japanese VSOP and Soviet Radioastron missions. The purpose of the study is to determine what quality of images can be expected from space VLBI, given realistic data errors and spacecraft orbits yielding incomplete UV coverage. Much of the paper is devoted to the problem of spurious symmetrization, and a method of overcoming this problem by using a set of UV-constraints is presented. Constraints limiting the imaging ability of the VSOP and Radioastron projects are discussed, and it is concluded that the application of constraints in either sky- or UV-plane will make it possible to overcome spurious symmetrization.