Weve talked plenty of times here about the infeasibility of launching a mirror big enough to directly image exoplanets using current rocket fairings - at least as long as were not sending them 500+ AU away to a gravitational lensing point. Weve also talked at length about the potential solution to that problem - interferometry, where multiple smaller satellites link up precisely, but are spaced far enough apart to act as one gigantic mirror. The problem is, from a technical standpoint, its really hard to build these kinds of systems. But the field has taken another step forward with a new paper from researchers at Xidian University and the Beijing Institute of Control Engineering, published in Space: Science & Technology, which describes a system to both control and calibrate a free-floating interferometer.