New spacecraft and satellites must be fitted with lasers to transmit digital signals back to optical telescopes on Earth, argue astronomers in a new analysis. The alternative is that the ever-increasing amount of data collected by their improved sensors will get jammed in a serious communications bottleneck, cramping the exploration of the Earth and Solar System Space missions currently being planned will collect several billion bits (gigabits) of data per second. Since the data can only be transmitted back to Earth for a short time every day or two, the satellites will need to transmit about 100 gigabits per second.