Deep Space 3 will fly a stellar optical interferometer on three separate spacecraft in heliocentric orbit: one spacecraft for the Michelson beam combining optics, and two spacecraft for each of the starlight apertures.

space-based↗

NASA NTRS1998

Deep Space 3 Metrology System

A metrology subsystem on board the Deep Space 3, a separated interferometer mission, is used to determine stellar fringe delay jitter, delay rate, and intial delay.

Deep↗

NASA NTRS1998

Enabling Design Concepts for a Flight-Qualifiable Optical Delay Line

In an interferometer, an Optical Delay Line(ODL) must be able to inject a commanded pathlength change in incoming starlight as it proceeds from a collecting aperture to the beam combiner.

interferometry↗

NASA NTRS1996

Separated Spacecraft Interferometer Concept for the New Millenium Program

A separated spacecraft optical interferometer mission concept proposed for NASA'a New Millenium Program is described. The interferometer insturment is distributed over three small spacecraft: two spacecraft serve as collectors, directing starlight toward a third spacecraft which combines the light and performs the interferometric detection.

optical↗

NASA NTRS1989

Active-member control of precision structures

This paper presents the results of closed loop experiments that use piezoelectric active-members to control the flexible motion of a precision truss structure. These experiments are directed toward the development of high performance structural systems as part of the Control/Structure Interaction program at JPL. Order of magnitude reductions in dynamic response are achieved with relatively simple control techniques. The practical implementation of high stiffness, high bandwidth active-members in a precision structure highlights specific issues of importance relating to the modelling and implementation of active-member control.

Fanson, J. L.↗

NASA NTRS1989

Uncertainty modelling for the control of an active structure

Two approaches to uncertainty modeling of a precision active truss structure for control design are presented. The first approach is based on the H(infinity) optimal control theory, which is used for robust control design with an additive uncertainty model. It is designed to provide vibration suppression to selected modes of the structure at the accelerometer locations. The uncertainty model can be used as an adjustable design parameter which will enable a study of the trade-offs between performance and robust stability. The second approach is based on mu-synthesis. Although the structured singular value can be used to analyze the robustness of any type of uncertainty, there exist difficulties in synthesis if the uncertainty block contains both real and complex variations. Mu-synthesis techniques do not allow for real-parameter variations in the synthesis procedure. The use of a complex variation description enclosing the real variation is suggested.

Blackwood, G. H.↗