Preparation of the pointing and control system of the SOFIA Airborne Telescope for early science missions

Ulrich Lampater; Terry Herter; Paul Keas; Franziska Harms; Christian Engfer; Peter Salewsky; Holger Jakob; Hans-Peter Roeser

doi:10.1117/12.856562

28 July 2010 Preparation of the pointing and control system of the SOFIA Airborne Telescope for early science missions

Ulrich Lampater, Terry Herter, Paul Keas, Franziska Harms, Christian Engfer, Peter Salewsky, Holger Jakob, Hans-Peter Roeser

Author Affiliations +

Proceedings Volume 7733, Ground-based and Airborne Telescopes III; 77330S (2010) https://doi.org/10.1117/12.856562
Event: SPIE Astronomical Telescopes + Instrumentation, 2010, San Diego, California, United States

Abstract

During observation flights the telescope structure of the Stratospheric Observatory for Infrared Astronomy (SOFIA) is subject to disturbance excitations over a wide frequency band. The sources can be separated into two groups: inertial excitation caused by vibration of the airborne platform, and aerodynamic excitation that acts on the telescope assembly (TA) through an open port cavity. These disturbance sources constitute a major difference of SOFIA to other ground based and space observatories and achieving the required pointing accuracy of 1 arcsecond cumulative rms or better below 70 Hz in this environment is driving the design of the TA pointing and control system. In the current design it consists of two parts, the rigid body attitude control system and a feed forward based compensator of flexible TA deformation. This paper discusses the characterization and control system tuning of the as-built system. It is a process that integrates the study of the structural dynamic behavior of the TA, the resulting image motion in the focal plane, and the design and implementation of active control systems. Ground tests, which are performed under controlled experimental conditions, and in-flight characterization tests, both leading up to the early science performance capabilities of the observatory, are addressed.

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Ulrich Lampater, Terry Herter, Paul Keas, Franziska Harms, Christian Engfer, Peter Salewsky, Holger Jakob, and Hans-Peter Roeser "Preparation of the pointing and control system of the SOFIA Airborne Telescope for early science missions", Proc. SPIE 7733, Ground-based and Airborne Telescopes III, 77330S (28 July 2010); https://doi.org/10.1117/12.856562

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