Session
Session VIII: Advanced Technologies & Subsystems, Components & Sensors II
Abstract
The detection of gravitational waves is important both because of the information about the astrophysical sources and the confirmation of general relativity that it will provide. Space-borne gravitational wave missions such as LISA and GAMMA require Drag-Free Control (DFC) systems to control the motion of a constellation of spacecraft to high positional accuracy so that Michelson interferometers of vast scales can be constructed and used to detect gravitational waves. The spacecraft will continually experience forces and torques due to external disturbances such as atmospheric drag and solar radiation pressure, which will result in the spacecraft being perturbed. Therefore the development of a DFC system is essential to control these spacecraft to a high positional accuracy so as to stabilize them to a specified tolerance over a finite frequency range. In doing such, the signals of interest from compact astrophysical bodies, namely, short-period binary stars or coalescing supermassive black-hole binaries, can be measured. Similar technology is also necessary on other missions where high positional accuracy is required. Additionally these precision thrusters, if they are small enough and consume minimal power, can be very useful on many small satellite missions. Examples include small satellites that need accurate attitude or missions that involve formation flying with accurate positional control requirements. Prior to space-borne gravitational wave missions, a technology demonstrator such as the proposed ODIE, ELITE or SMART-2 missions is needed to test the feasibility of a drag-free spacecraft and the technology involved. This paper discusses some requirements of the associated hardware (e.g., accelerometers, etc.) needed to implement a DFC system for a technology demonstration mission, but primarily focuses on defining the requirements of the type of thruster required for implementing a DFC system. In particular, it presents an overview of current thruster technology and briefly discusses possible alternative technologies that could be applied to the development of a new micro-Newton thruster.
Discussion of Micro-Newton Thruster Requirements for a Drag-Free Control System
The detection of gravitational waves is important both because of the information about the astrophysical sources and the confirmation of general relativity that it will provide. Space-borne gravitational wave missions such as LISA and GAMMA require Drag-Free Control (DFC) systems to control the motion of a constellation of spacecraft to high positional accuracy so that Michelson interferometers of vast scales can be constructed and used to detect gravitational waves. The spacecraft will continually experience forces and torques due to external disturbances such as atmospheric drag and solar radiation pressure, which will result in the spacecraft being perturbed. Therefore the development of a DFC system is essential to control these spacecraft to a high positional accuracy so as to stabilize them to a specified tolerance over a finite frequency range. In doing such, the signals of interest from compact astrophysical bodies, namely, short-period binary stars or coalescing supermassive black-hole binaries, can be measured. Similar technology is also necessary on other missions where high positional accuracy is required. Additionally these precision thrusters, if they are small enough and consume minimal power, can be very useful on many small satellite missions. Examples include small satellites that need accurate attitude or missions that involve formation flying with accurate positional control requirements. Prior to space-borne gravitational wave missions, a technology demonstrator such as the proposed ODIE, ELITE or SMART-2 missions is needed to test the feasibility of a drag-free spacecraft and the technology involved. This paper discusses some requirements of the associated hardware (e.g., accelerometers, etc.) needed to implement a DFC system for a technology demonstration mission, but primarily focuses on defining the requirements of the type of thruster required for implementing a DFC system. In particular, it presents an overview of current thruster technology and briefly discusses possible alternative technologies that could be applied to the development of a new micro-Newton thruster.
