James Webb Space Telescope primary and secondary mirror segment assembly cleaning: a quantitative assessment

Alan C. Abeel; Yingrui "Zhao" Huang

doi:10.1117/12.2325985

19 September 2018 James Webb Space Telescope primary and secondary mirror segment assembly cleaning: a quantitative assessment

Alan C. Abeel, Yingrui "Zhao" Huang

Author Affiliations +

Proceedings Volume 10748, Systems Contamination: Prediction, Control, and Performance 2018; 107480I (2018) https://doi.org/10.1117/12.2325985
Event: SPIE Optical Engineering + Applications, 2018, San Diego, California, United States

Abstract

The James Webb Space Telescope Primary Mirror Segment Assemblies (PMSAs) and Secondary Mirror Assembly (SMA) were cleaned at the Johnson Space Center (JSC) in January 2018. In order to quantify the effectiveness of the cleaning, the same cleaning process was performed on the PMSA and SMA traveling witness wafers. These wafers have accompanied their respective mirror segments from their arrival at the Goddard Space Flight Center, through transport to JSC, and ultimately their exposure in Chamber A for cryogenic testing. The traveling wafers were analyzed using an Image Analysis automated microscope both prior to and after the cleaning. The resulting data showed that the PMSA wafers’ Percent Area Coverage (PAC) reduced by 83.5% on average, from 0.1524 PAC to 0.0251 PAC. The SMA wafer’s PAC decreased by 97.2%, from 0.1194 PAC to 0.0034 PAC. Further analysis of the particle size bins was completed in order to calculate their particle distribution slopes. The slope of the PMSA wafers increased by 0.025 on average, and the SMA wafer slope increased by 0.066. This indicates that the ratio of large to small particles slightly increased after the cleaning across all mirror segments. Visual inspections of the wafers and the flight PMSAs and SMA showed considerable and comparable particulate coverage improvements, thus leading to the conclusion that the average PAC on the PMSAs and SMA improved by the same factor as their respective wafers.

Citation Download Citation

Alan C. Abeel and Yingrui "Zhao" Huang "James Webb Space Telescope primary and secondary mirror segment assembly cleaning: a quantitative assessment", Proc. SPIE 10748, Systems Contamination: Prediction, Control, and Performance 2018, 107480I (19 September 2018); https://doi.org/10.1117/12.2325985

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available