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Proceedings Paper

Achieving high-precision pointing on ExoplanetSat: initial feasibility analysis
Author(s): Christopher M. Pong; Sungyung Lim; Matthew W. Smith; David W. Miller; Jesus S. Villaseñor; Sara Seager
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Paper Abstract

ExoplanetSat is a proposed three-unit CubeSat designed to detect down to Earth-sized exoplanets in an orbit out to the habitable zone of Sun-like stars via the transit method. To achieve the required photometric precision to make these measurements, the target star must remain within the same fraction of a pixel, which is equivalent to controlling the pointing of the satellite to the arcsecond level. The satellite will use a two-stage control system: coarse control will be performed by a set of reaction wheels, desaturated by magnetic torque coils, and fine control will be performed by a piezoelectric translation stage. Since no satellite of this size has previously demonstrated this high level of pointing precision, a simulation has been developed to prove the feasibility of realizing such a system. The current baseline simulation has demonstrated the ability to hold the target star to within 0.05 pixels or 1.8 arcseconds (with an 85 mm lens and 15 μm pixels), in the presence of large reaction wheel disturbances as well as external environmental disturbances. This meets the current requirement of holding the target star to 0.14 pixels or 5.0 arcseconds. Other high-risk aspects of the design have been analyzed such as the effect of changing the guide star centroiding error, changing the CMOS sampling frequency, and reaction wheel selection on the slew performance of the satellite. While these results are promising as an initial feasibility analysis, further model improvements and hardware-in-the-loop tests are currently underway.

Paper Details

Date Published: 6 August 2010
PDF: 16 pages
Proc. SPIE 7731, Space Telescopes and Instrumentation 2010: Optical, Infrared, and Millimeter Wave, 77311V (6 August 2010); doi: 10.1117/12.857992
Show Author Affiliations
Christopher M. Pong, Massachusetts Institute of Technology (United States)
Sungyung Lim, The Charles Stark Draper Lab., Inc. (United States)
Matthew W. Smith, Massachusetts Institute of Technology (United States)
David W. Miller, Massachusetts Institute of Technology (United States)
Jesus S. Villaseñor, Massachusetts Institute of Technology (United States)
Sara Seager, Massachusetts Institute of Technology (United States)


Published in SPIE Proceedings Vol. 7731:
Space Telescopes and Instrumentation 2010: Optical, Infrared, and Millimeter Wave
Jacobus M. Oschmann; Mark C. Clampin; Howard A. MacEwen, Editor(s)

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