Laser-Guide-Star Satellite for Ground-Based Adaptive Optics Imaging of Geosynchronous Satellites

In this study, the feasibility and utility of using a maneuverable nanosatellite laser guide star from a geostationary equatorial orbit have been assessed to enable ground-based, adaptive optics imaging of geosynchronous satellites with next-generation extremely large telescopes. The concept for a satellite guide star was first discussed in the literature by Greenaway and Clark in the early 1990s ("PHAROS: An Agile Satellite-Borne Laser Guidestar," Proceedings of SPIE, Vol. 2120, 1994, pp. 206-210), and expanded upon by Albert in 2012 ("Satellite-Mounted Light Sources as Photometric Calibration Standards for Ground-Based Telescopes," Astronomical Journal, Vol. 143, No. 1, 2012, p. 8). With a satellite-based laser as an adaptive optics guide star, the source laser does not need to scatter, and is well above atmospheric turbulence. When viewed from the ground through a turbulent atmosphere, the angular size of the satellite guide star is much smaller than a backscattered source. Advances in small-satellite technology and capability allowed the revisiting of the concept on a 6UCubeSat, measuring 10 × 20 × 30 cm. It is shown that a system that uses a satellite-based laser transmitter can be relatively low power (∼1 W transmit power) and operated intermittently. Although the preliminary analysis indicates that a single satellite guide star cannot be used for observing multiple astronomical targets, it will only require a little propellant to relocate within the geosynchronous belt. Results of a design study on the feasibility of a small-satellite guide star have been presented, and the potential benefits to astronomical imaging and to the larger space situational awareness community have been highlighted.
United States. Air Force Office of Scientific Research (Contract FA8721-05-C-0002)
Air Force Office of Scientific Research (Contract FA8702-15-D-0001)