A Contamination-Free Ultrahigh Precision Formation Flight Method Based on Intracavity Photon Thrusters and Tethers: Photon Tether Formation Flight (PTFF)

Formation flying of clusters of micro-, nanoand pico-satellites has been recognized to be more affordable,robust and versatile than building a large monolithic satellite in implementing next generation space missions requiringlarge apertures or large sample collection areas and sophisticated earth imaging/monitoring. We propose a propellantfree, thus contamination free, method that enables ultrahigh precision satellite formation flying with intersatellitedistance accuracy of nm (10 m) at maximum estimated distances in the order of tens of km. The method is based onultrahigh precision CW intracavity photon thrusters and tethers. The pushing-out force of the intracavity photonthruster and the pulling-in force of the tether tension between satellites form the basic force structure to stabilizecrystalline-like structures of satellites and/or spacecrafts with a relative distance accuracy better than nm. The thrust ofthe photons can be amplified by up to tens of thousand times by bouncing them between two mirrors located separatelyon pairing satellites. For example, a 10 W photon thruster, suitable for micro-satellite applications, is theoreticallycapable of providing thrusts up to mN, and its weight and power consumption are estimated to be several kgs and tensof W, respectively. The dual usage of photon thruster as a precision laser source for the interferometric ranging systemfurther simplifies the system architecture and minimizes the weight and power consumption. The present method doesnot require propellant, thus provides significant propulsion system mass savings, and is free from propellant exhaustcontamination, ideal for missions that require large apertures composed of highly sensitive sensors. The system can bereadily scaled down for the nanoand pico-satellite applications.