Optical terminals for microsatellite swarms

We studied terminal architectures and configurations for optical cross-links within microsatellite swarms and assessed the applicability of available technologies. Typical applications for microsatellite swarm are phased array telescopes, interferometric missions, and space-based radar. Key drivers for an optical terminal are well-developed technology and ruggedness. The terminal should do without automatic tracking or fine pointing, coarse pointing should be simple. As an example we cover a scenario where four microsatellites form a planar, square formation of 1 km side length, where the data rate is 100 kbit/s, and where an active double-pass lidar between each of the satellites provides a ranging accuracy of better than 10 m. The terminal transmit power is some 160 mW at a wavelength of 980 nm, the receive apertures have a diameter 3 of 5 min, and the size, weight, and power requirement of one terminal is estimated to be 60x80x70 mm(3), 900 g, and 5 W, respectively.