NASA puts more money into photon-thruster spacecraft control
September 15, 2006, Tustin, CA--In an apparent vote of confidence for development of photon-thruster formation-flight (PTFF) spacecraft in ultraprecise formations, the NASA Institute for Advanced Concepts (NIAC; Atlanta, GA) awarded a Phase II $400,000 grant to the Bae Institute.
In the PTFF concept, arrays of small spacecraft are kept in precise formation (to subnanometer accuracy) by the pressure exerted by light beams bouncing back and forth many times between mirrors mounted on the spacecraft (see www.laserfocusworld.com/articles/259915). The approach is aimed at both earth-based observation and outward-looking space-observation applications. With PTFF, no propellants besides light are needed, providing mass and energy savings, extended spacecraft utility, and contaminant-free operation for missions requiring highly sensitive sensors.
The grant followed a NIAC $75,000 Phase I grant last March that enabled the Bae Institute to research and present the viability of the photon thrusters and tethers to control formations of spacecraft. In Phase II, the Bae Institute will demonstrate control and system stability of a photon-thruster/tether (push/pull) in a vacuum chamber with off-the-shelf components. Photon thrust will be measured and a means of thrust optimization will be demonstrated.
The Bae Institute's objective is to convince the space-research community to fund a full-scale working PTFF system. The benefits of deploying a network of small, inexpensive spacecraft functioning together within a highly sensitive distributed array are tantalizing. In the USA, NASA and the Jet Propulsion Lab (Pasadena, CA) are actively pursuing such research. The European Space Agency (ESA) is perhaps further along in its Proba-3 series of missions for validating developments in formation flying of multiple spacecraft. The Chinese, in collaboration with the UK, have also attempted formation flying of spacecraft. However, controlling such a network to any degree of precision without contamination from propellants has proven illusive.
Applications of PTFF-equipped satellite arrays include environmental monitoring, mapping, imaging, surveillance, astronomy, and global-positioning systems. Spacecraft clusters in geosynchronous orbit (about 23,000 miles up) could resolve geophysical detail to within 10 cm (approximately equivalent to today's satellite imaging from low-earth orbits of about 100 miles up) while providing real-time data streaming. For astronomical imaging and asteroid warning and exploration applications, PTFF is projected to provide a thousandfold increase in image resolution and scanning accuracy when compared with that of the Hubble Space Telescope at a fraction of the cost.