Pointing Performance Analysis Of A Prototype Secondary Mirror Assembly For The Space Infrared Telescope Facility

Sarma N. Gullapalli; Mark T. Stier; Michael A. Duffy; Richard A. Rockwell; Francis R. Sileo; Michael H. Krim

doi:10.1117/12.977969

26 September 1989 Pointing Performance Analysis Of A Prototype Secondary Mirror Assembly For The Space Infrared Telescope Facility

Sarma N. Gullapalli, Mark T. Stier, Michael A. Duffy, Richard A. Rockwell, Francis R. Sileo, Michael H. Krim

Author Affiliations +

Proceedings Volume 1111, Acquisition, Tracking, and Pointing III; (1989) https://doi.org/10.1117/12.977969
Event: SPIE 1989 Technical Symposium on Aerospace Sensing, 1989, Orlando, FL, United States

Abstract

The Space Infrared Telescope Facility (SIRTF), a NASA "Great Observatory" to be launched in the late 1990s, is a superfluid helium-cooled one meter class IR telescope with a sophisticated chopping facility provided by a dynamic two-axis tilt control capability of the secondary mirror. This paper describes the pointing performance analysis of the Prototype Secondary Mirror Assembly (PSMA) design. The two-axis PSMA tilt control system employs four linear actuators and four pairs of position eddy current sensors, and a reaction mass system to isolate the servo loops from the structural modes. The actuators and sensors operate in the 4 K environment of the secondary mirror assembly, while the control electronics reside in the "warm" electronics box outside the dewar. The PSMA design meets stringent pointing performance requirements over a range of discrete chop amplitudes and frequencies, for three different dynamic chop modes. The analysis of the pointing performance utilizes a detailed dynamic model of the PSMA in time and frequency domains, including the discretization and quantization effects in the servo-controllers, the sensor noise, and the structural modes. The servo stability issues are also addressed.

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Sarma N. Gullapalli, Mark T. Stier, Michael A. Duffy, Richard A. Rockwell, Francis R. Sileo, and Michael H. Krim "Pointing Performance Analysis Of A Prototype Secondary Mirror Assembly For The Space Infrared Telescope Facility", Proc. SPIE 1111, Acquisition, Tracking, and Pointing III, (26 September 1989); https://doi.org/10.1117/12.977969

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