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Houghton, M.

Publications and source records attributed to Houghton, M..

3 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2004

Thruster Placement Issues and Possible Mitigation Methods for the ST-7 Disturbance Reduction System

The Space Technology-7 Disturbance Reduction System is being designed to demonstrate the ability to shield a test mass from non-gravitational forces. In order to meet this goal, two advanced technologies will be employed: a highly sensitive Gravitational Reference Sensor and micro-Newton thrusters. ST-7 is limited to two clusters of four thrusters, which are sufficient to provide control for 6 degrees of freedom, but the overall effectiveness of the baseline configuration is limited by the noise on the measurement signals and the thrust outputs, the disturbance force caused by solar radiation pressure, and the performance of the individual thrusters. This paper presents and discusses these issues in greater detail along with possible mitigation methods.

Hsu, O.↗
NASA NTRS2003

ST7-DRS: A Step Towards Drag-free and High-precision Formation Control

The Space Technology 7 Disturbance Reduction System (ST7-DRS) is an in-space technology demonstration within NASA's New Millennium Program. ST7-DRS is designed to validate system-level technologies that are required for future gravity missions (including the planned LISA gravitational-wave observatory) and for future formation-flying interferometer missions (including the planned MAXIM black-hole imager). ST7-DRS is based around a freely-floating test mass contained within a spacecraft structure that will shield this test mass from all external forces (aside from gravity). The spacecraft position will be continuously controlled, such that the spacecraft, itself, will remain centered about this test mass, essentially flying in formation with it. Colloidal micro-thrusters will be used to control the spacecraft s position to within a few nanometers, over time scales of tens to thousands of seconds. In order to detect the residual acceleration noise on the main test mass, a second test mass will be flown alongside the first, within the same physical spacecraft structure. This test mass will serve as a cross-reference for the first, and will also be used as a reference for the spacecraft's attitude control. The spacecraft's attitude will be controlled to an accuracy of a few milli-arc-seconds, also utilizing the colloidal micro-thrusters. ST7-DRS will consist of an instrument package (containing the test masses) and a set of micro-thrusters, which will be attached to the European Space Agency s SMART-2 spacecraft, set to launch in November 2007.

Houghton, M.↗