Mr. Keith Coste Profile

Keith Coste

at Jet Propulsion Lab

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Author

Publications (3)

Proceedings Article | 29 August 2022 Presentation + Paper

Characterization of multilayer piezoelectric stacks down to 100K for surface parallel mirror actuation

Stewart Sherrit, Carey L. Weisberg, Erin Sidick, Will Krieger, Carlos Gross Jones, Scott A. Basinger, Clifford A. Klein, Mircea Badescu, Alexander J. Ramirez, Joseph Sauvageau, Keith Coste

Proceedings Volume 12188, 121881N (2022) https://doi.org/10.1117/12.2634962

KEYWORDS: Actuators, Mirrors, Ferroelectric materials, Wavefronts, Aluminum, Control systems, Ceramics, Titanium, Power supplies, Capacitance, Piezoelectric driven mechanisms

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The next generation of space telescopes will require large segmented apertures for observations in the near ultraviolet through mid and far-infrared regions to enable new science ranging from exoplanet characterization to precision astronomical observations that refine astrophysics models. Recent concept studies, such as LUVOIR, HabEx, and Origins, and the future IR/O/UV Large Strategic Mission telescope for exoplanet characterization and general astronomy discussed in the 2021 Decadal Survey "Pathways to Discovery in Astronomy and Astrophysics for the 2020s” include segmented telescopes that are capable of observations in UV through IR bands and thus drive the need for optical surface performance at cryogenic temperatures. These spaceborne mirror applications require precision control, and these segments will require actuators for controlled surface displacements capable of operation at cryogenic temperatures (<150 K). This paper presents a testbed mirror design to test out new actuators and control strategies. This work is directed at understanding the performance of piezoelectric multilayer stack actuator operation down to 100 K, which will provide actuator designers the critical information needed to model and predict performance. The data reported down to 100 K include: displacement/strain and capacitance as a function of applied voltage, stiffness, hysteresis, blocking force, DC resistance measurements, thermal strains, and the coefficients of thermal expansion as a function of the electrical boundary conditions. The actuators include a strain gauge to allow for closed loop control. This approach allows for a comparison of potential open-loop control drive strategies and associated errors reported in previous work. Surface actuation measurements using flexure-based actuators on aluminum mirror segments at room temperature will also be presented. In addition, we will present techniques to optimize displacement per voltage using amplified piezoelectric flexures and the potential to develop mirrors that can be operated at cryogenic temperatures by carefully choosing flexure materials and geometry.

Proceedings Article | 9 September 2019 Presentation + Paper

A Habitable Exoplanet Observatory (HabEx) starshade-only architectures

David Redding, Keith Coste, Otto Polanco, Claudia Pineda, Kevin Hurd, Howard Tseng, Stefan Martin, Rhonda Morgan, Kevin Schulz, Jonathan Tesch, Eric Cady, Michael Rodgers, Matthew East, Chris Stark, Gordon Wu, Pei Huang, Bradley Hood, Derek Chan, Dustin Putnam, Suzan Greene, Sandra Johnson, Jonathan Benson

Proceedings Volume 11115, 111150V (2019) https://doi.org/10.1117/12.2529646

KEYWORDS: Telescopes, Ultraviolet radiation, Mirrors, Space operations, Interfaces, Actuators, Exoplanets, Electronics, Imaging spectroscopy, Observatories

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Proceedings Article | 6 July 2018 Presentation + Paper

HabEx Lite: a starshade-only habitable exoplanet imager alternative

David Redding, Keith Coste, Otto Polanco, Claudia Pineda, Kevin Hurd, Howard Tseng, Jose Quezada, Stefan Martin, Joel Nissen, Kevin Schulz, Jonathan Tesch, Eric Cady, Michael Rodgers, Matthew East, James Mooney, Chris Stark

Proceedings Volume 10698, 106980X (2018) https://doi.org/10.1117/12.2310058

KEYWORDS: Mirrors, Coronagraphy, Space telescopes, Imaging spectroscopy, Telescopes, Ultraviolet radiation, Exoplanets, Control systems, Observatories, Planets

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