The James Webb Space Telescope (JWST) spent considerable time in multiple clean facilities during its launch campaign at the Centre Spatial Guyanais (CSG) in French Guiana. Throughout this time, it was imperative that personnel wear approved cleanroom or safety suits when working in proximity to the JWST observatory. This proved to be challenging for two reasons:
1) A large quantity of NASA cleanroom suits needed to be shipped to CSG to account for the heavy volume of NASA and ESA personnel requiring access to the clean facilities. It became evident that shipping clean suits from the US to CSG in a timely fashion during the launch campaign would be challenging. Consequently, a backup plan needed to be established to avoid running out.
2) For safety purposes, Self-Contained Atmospheric Protection Ensemble (SCAPE) and Splash suits were required for hazardous operations. Neither type of suit was cleanroom compatible; therefore, a viable cleaning process needed to be developed to ensure both types of suits met JWST’s approved cleanliness standards.
The NASA Contamination Control (CC) team partnered with CSG’s S5E cleanroom and suit processing team. The teams were able to make modifications to the S5E facility to create a NASA approved makeshift clean environment where NASA cleanroom suits and CSG Splash suits were inspected, folded, and bagged for cleanroom use once they were washed and dried. Since SCAPE suits could not be cleaned using conventional methods, a procedure was developed to clean and inspect the suits by the CC team in a temporary clean environment prior to fueling.
KEYWORDS: James Webb Space Telescope, Contamination, Picture Archiving and Communication System, Rockets, Mirrors, Inspection, Telescopes, Optical fibers, Observatories, Contamination control
Over the life of the James Webb Space Telescope (JWST), Integration & Test (I&T) has taken place in areas that needed considerable work to make the facility itself and/or the protocols used while working in the rooms suitable to meet JWST percent area coverage (PAC) and molecular accumulation requirements. In addition to normal particulate matter, JWST had a uniquely significant challenge: fibers! Fibers not only cause much higher PAC levels, but they also risk damaging the angstrom sized Near Infrared Spectrometer (NIRSpec) microshutter array (MSA), which is critical to NIRSpec instrument performance. The primary emphasis of this paper is to address particulate and fiber contamination. The success of the JWST mission required effective cleanrooms, protocols, and mitigations in non-cleanroom areas that were pressed into service to house contamination-sensitive optics and scientific instruments. Some presented profound challenges. These included: NASA’s 60-year-old Johnson Space Center (JSC) Chamber A, which had never been used for anything contamination-sensitive, and the European tropical launch facilities, which were designed to meet International Standard Organization (ISO) Class 8 processing for communication satellites. The final challenge for JWST, as if to stare us in the face and say, “I dare you to try and make me clean enough,” was preparing the 4 areas in the Centre Spatial Guyanais (CSG) Final Assembly Building (BAF) located in French Guiana, a building in which one entire side opens for Ariane 5 rocket ingress and egress. This paper will describe our initial evaluation processes and the actual work undertaken to transform even the most challenging areas into first class cleanrooms that met JWST particulate and fiber requirements.
The James Webb Space Telescope (JWST) has a primary mirror, made of 18 segments, and a secondary mirror (SM) that are used to direct the light of desired targets. After launch, the secondary mirror assembly (SMA) is stowed for approximately 10 days and is subject to molecular contamination outgassing from the cavity of the secondary mirror support structure (SMSS) in-board hinge (IBH) which contains cables, motors, resolvers, and coatings. The main concern during this period before SMA deployment is the accumulation of ice due to the lack of a heater on the SMA. The temperature differentials between the IBH surfaces and SMA could cause redistribution of water vapor contamination. To address this concern, single layer insulation (SLI) was reconfigured to direct the vent path of IBH outgassing sources away from the SM. Two separate thermal vacuum (TVAC) tests were performed to quantify this contamination: a Z307 ASTM E 1559 materials test of the radiator paint used on the motor of the IBH and a separate test on the hinge motor from the primary mirror backplane assembly (PMBA) qualification engineering test unit (ETU). The PMBA ETU hinge was similar in design to the IBH. These tests approximately followed the predicted SMA predeployment thermal environment. To quantify source rates in case of a leak in the new SLI enclosure or baffle, the motor and resolver sides were separated, and quartz crystal microbalances (QCM) were used to measure the deposition of water. The SLI redesign and implementation and outgassing measurements to understand leak effects from the IBH were essential to mitigate the deposition of contamination on the SMA.
KEYWORDS: James Webb Space Telescope, Contamination, Mirrors, Semiconducting wafers, Picture Archiving and Communication System, CFD analysis, Camera shutters, Particles, Observatories, Safety
In preparation for the James Webb Space Telescope (JWST) launch at the Centre Spatial Guyanias (CSG) in French Guiana, particulate contamination accumulation predictions were necessary for each facility in which the hardware would be exposed because the Telescope would be uncovered in each of the facilities and had strict particulate requirements. These included facilities for final integration and testing, fueling, transportation and encapsulation. Minimal heritage data existed from CSG and previous launch campaigns to use as a basis for contamination predictions. Data from the Automatic Transfer Vehicle and Herschel-Planck launch campaigns were used in conjunction with facility monitoring data provided by the European Space Agency (ESA) and data collected during a JWST working group visit to CSG. These campaigns were conducted at varying cleanliness levels that were typically less stringent than JWST requirements. Each facility was evaluated using the data provided and likely performance improvement with the addition of High Efficiency Particulate Air filter (HEPA) banks operating when possible. Once the launch campaign was completed, the predicted fallout was compared with actual data collected throughout the campaign. Based on the actual measurements, JWST’s primary and secondary mirrors turned out to be much cleaner than what was predicted.
A challenge present in assessing contamination accumulation on many missions is predicting fallout during ground processing given the multiple and various orientations possible for surfaces such as optics and instruments. The best practice assumption has been to quantify particle build up on vertical surfaces as approximately 1/10 that of horizontal surfaces. There is insufficient data to provide confidence in the 1/10 approximation, yet its use can have a significant effect on mission end of life contamination level predictions, leading to expenditures of precious resources to meet mission requirements. There are many variables influencing the relationship between fallout on vertical and horizontal wafers, including wafer position with respect to air flow, air changes in the facility, duration of exposure, and activity workload. The goal of this continuing study is to develop a tool to inform particulate accumulation predictions for future projects.
The James Webb Space Telescope (JWST), expected to launch in 2021, will be the next premier observatory for astronomers worldwide. It is optimized for infrared wavelengths and observation 1.5 million kilometers from Earth. JWST includes an Integrated Science Instrument Module (ISIM) that contains the four main instruments used to observe deep space: Near-Infrared Camera (NIRCam), Near-Infrared Spectrograph (NIRSpec), Mid-Infrared Instrument (MIRI), and Fine Guidance Sensor/Near InfraRed Imager and Slitless Spectrograph (FGS/NIRISS)1.
JWST will make ultra-deep near-infrared surveys of the Universe to see back 13.5 billion years to “First Light” which occurred 100 – 250 million years after the Big Bang when the first stars and galaxies formed. Its ability to observe very high redshifts will enable astronomers to study the faintest galaxies, observe stars forming within clouds of dust, determine how galaxies evolved, and search for exoplanets1,2.
JWST is extremely sensitive to even small amounts of contamination, which can directly cause degradation to performance of the telescope, and impact the mission lifetime. Contamination control has been an essential focus of this mission since conception of the JWST observatory3.
In-Situ Resource Utilization (ISRU) is a key NASA initiative to exploit resources at the site of planetary exploration for mission-critical consumables, propellants, and other supplies. The Resource Prospector mission, part of ISRU, is scheduled to launch in 2020 and will include a rover and lander hosting the Regolith and Environment Science and Oxygen and Lunar Volatile Extraction (RESOLVE) payload for extracting and analyzing lunar resources, particularly low molecular weight volatiles for fuel, air, and water. RESOLVE contains the Lunar Advanced Volatile Analysis (LAVA) subsystem with a Gas Chromatograph-Mass Spectrometer (GC-MS). RESOLVE subsystems, including the RP15 rover and LAVA, are in NASA’s Engineering Test Unit (ETU) phase to assure that all vital components of the payload are space-flight rated and will perform as expected during the mission. Integration and testing of LAVA mass spectrometry verified reproducibility and accuracy of the candidate MS for detecting nitrogen, oxygen, and carbon dioxide. The RP15 testing comprised volatile analysis of water-doped simulant regolith to enhance integration of the RESOLVE payload with the rover. Multiple tests show the efficacy of the GC to detect 2% and 5% water-doped samples.
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