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Proceedings Paper

NuSTAR: system engineering and modeling challenges in pointing reconstruction for a deployable x-ray telescope
Author(s): D. Isaiah Harp; Carl Christian Liebe; William Craig; Fiona Harrison; Kristin Kruse-Madsen; Andreas Zoglauer
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Paper Abstract

The Nuclear Spectroscopic Telescope Array (NuSTAR) is a NASA Small Explorer mission that will make the first sensitive images of the sky in the high energy X-ray band (6 - 80 keV). The NuSTAR observatory consists of two co-aligned grazing incidence hard X-ray telescopes with a ~10 meter focal length, achieved by the on-orbit extension of a deployable mast. A principal science objective of the mission is to locate previously unknown high-energy X-ray sources to an accuracy of 10 arcseconds (3-sigma), sufficient to uniquely identify counterparts at other wavelengths. In order to achieve this, a star tracker and laser metrology system are an integral part of the instrument; in conjunction, they will determine the orientation of the optics bench in celestial coordinates and also measure the flexures in the deployable mast as it responds to the varying on-orbit thermal environment, as well as aerodynamic and control torques. The architecture of the NuSTAR system for solving the attitude and aspect problems differs from that of previous X-ray telescopes, which did not require ex post facto reconstruction of the instantaneous observatory alignment on-orbit. In this paper we describe the NuSTAR instrument metrology system architecture and implementation, focusing on the systems engineering challenges associated with validating the instantaneous transformations between focal plane and celestial coordinates to within the required accuracy. We present a mathematical solution to photon source reconstruction, along with a detailed error budget that relates component errors to science performance. We also describe the architecture of the instrument simulation software being used to validate the end-to-end performance model.

Paper Details

Date Published: 4 August 2010
PDF: 12 pages
Proc. SPIE 7738, Modeling, Systems Engineering, and Project Management for Astronomy IV, 77380Z (4 August 2010); doi: 10.1117/12.856626
Show Author Affiliations
D. Isaiah Harp, Jet Propulsion Lab. (United States)
Carl Christian Liebe, Jet Propulsion Lab. (United States)
William Craig, Univ. of California, Berkeley (United States)
Fiona Harrison, California Institute of Technology (United States)
Kristin Kruse-Madsen, California Institute of Technology (United States)
Andreas Zoglauer, Univ. of California, Berkeley (United States)

Published in SPIE Proceedings Vol. 7738:
Modeling, Systems Engineering, and Project Management for Astronomy IV
George Z. Angeli; Philippe Dierickx, Editor(s)

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