JWST cryo fine guidance closed loop test results

Vila, M. Begona; Lambros, Scott; Diaz, David M.; Fu, Henry; Lee, Steven; Meza, Luis; Phillips, Kevin J.; Rosario, Ben del; Jiang, Wu

doi:10.1117/12.2311516

Cited by 5 publications

(1 citation statement)

References 10 publications

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“…End-to-end hardware testing involving all the components and their flight-like interactions was not possible but many portions that could be tested stand alone were identified. 4 Executing those tests with the flight hardware to reduce risk was key as well. Another important portion was identifying timing budgets for the different operations and checking those timing operations out incrementally.…”

Section: Fine Guidance Control Loopmentioning

confidence: 99%

James Webb Space Telescope optical stability lessons learned for future great observatories

Feinberg,

McElwain,

Bowers

et al. 2023

J. Astron. Telesc. Instrum. Syst.

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The James Webb Space Telescope (JWST) launched on December 25, 2021, and its optical performance in orbit has been even better than predicted pre-flight. The static wavefront error (WFE) is less than half the value specified for the requirement of having diffraction-limited image quality at 2 microns in the NIRCam shortwave channel, enabling the observatory to deliver both sharper images and higher sensitivity than anticipated. In addition to the excellent image quality, the optical stability has also exceeded expectations, both in terms of high-frequency dynamic contributions (which would be perceived as part of "static WFE") and in terms of drifts over minutes, hours, and days. Stability over long timescales is critical for several important science cases, including exoplanet transit spectroscopy and coronagraphy. JWST's stability success was achieved through detailed design and testing, with several important lessons learned for future observatories, especially the Habitable Worlds Observatory that is expected to need even higher levels of stability. We review the stability architecture, how it was technologically demonstrated, the ground test results and improvements, the on-orbit results, and the lessons learned.

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Section: Fine Guidance Control Loopmentioning

confidence: 99%

James Webb Space Telescope optical stability lessons learned for future great observatories

Feinberg,

McElwain,

Bowers

et al. 2023

J. Astron. Telesc. Instrum. Syst.

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The closed-loop control method based on dual-port adaptive internal model control for fine image stabilization of space telescopes

Gao,

Zhang,

Wei

et al. 2023

Review of Scientific Instruments

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In view of the complex working environment of space astronomical telescopes, the influence of various disturbance sources on the imaging quality cannot be ignored. This paper focuses on compensating for the space telescope line-of-sight (LOS) deviation and suppressing the low-frequency disturbance problem in astronomical observation. A closed-loop control method based on dual-port adaptive internal model control (AIMC) for the fine image stabilization system (FISS) was proposed. To be specific, the fine guidance sensor (FGS) as the high-precision detection unit of the FISS calculates the telescope LOS deviation and sends it to the controller unit in real time. The controller unit drives the large-aperture fast steering mirror (FSM), which performs high-precision two-dimensional rotation to compensate for the telescope LOS deviation, according to the dual-port AIMC control algorithm. Moreover, the dual-port AIMC control method adds an AIMC loop on the basis of the feedback loop and adjusts the filter parameters adaptively according to the target angular velocity of the FSM, achieving higher disturbance suppression capability. The experimental results verify that the control method proposed can effectively compensate for the LOS deviation and suppress the composite frequency disturbance. In the 0–8 Hz frequency band, the power spectral density integral values of the star centroid deviation in the X and Y directions of the FGS are, respectively, suppressed by 97.38% and 98.38%.

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Commanding the James Webb Space Telescope: OSS and Event-Driven Operations

Elliott

2023

IEEE Women Eng. Mag.

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JWST cryo fine guidance closed loop test results

Cited by 5 publications

References 10 publications

James Webb Space Telescope optical stability lessons learned for future great observatories

James Webb Space Telescope optical stability lessons learned for future great observatories

The closed-loop control method based on dual-port adaptive internal model control for fine image stabilization of space telescopes

Commanding the James Webb Space Telescope: OSS and Event-Driven Operations

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