Phys.org  December 14, 2018 CubeSats struggle to efficiently transmit large amounts of data down to Earth due to power and size constraints. To fine-point its downlink beam, researchers at MIT utilize an uplink beacon signal captured by an on-board detector and tracked by an off-the-shelf MEMS fast steering mirror. As these miniature actuators lack feedback sensors, the system design is augmented with an optical calibration signal to provide the mirror’s pointing feedback. They developed calibration algorithms utilizing the feedback signal to achieve higher fidelity beam pointing control. Experimental results show that beacon tracking errors of only 16 μrad root-mean-square are feasible […]