High-precision cryogenic wheel mechanisms of the JWST/MIRI instrument: performance of the flight models

Krause, O.; Müller, Friedrich; Birkmann, Stephan M.; Böhm, A.; Ebert, M.; Grözinger, U.; Henning, Th.; Hofferbert, R.; Huber, Armin; Lemke, D.; Rohloff, R. R.; Scheithauer, S.; Gross, T.; Luichtel, Georg; Merkle, Hellmut; Übele, M.; Wieland, Hans-Ulrich; Amiaux, J.; Jäger, R.; Glauser, Adrian M.; Parr-Burman, P.; Sykes, J.

doi:10.1117/12.856887

Cited by 12 publications

(6 citation statements)

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“…Sputtered MoS2 films, which may, in the as-sputtered state, consist of mainly columnar (with MoS2 crystallites oriented perpendicular to the substrate) or basal (with MoS2 crystallites oriented parallel to the substrate) morphologies [48], are utilized both for fundamental studies [49] as well as critical applications, e.g. as solid lubricants on bearings employed in spacecraft [7,50]. A particular advantage of the sputtering method is that other materials can be co-sputtered with MoS2 relatively easily in order to achieve doped coatings with improved properties [15], as discussed further in Section 7.…”

Section: Polytypementioning

confidence: 99%

“…Based on the fact that MoS2 is the most extensively used solid lubricant in space mechanisms, a particularly timely example will be highlighted here: the James Webb Space Telescope (JWST), which is planned for launch in 2021 and is the successor to the Hubble Space Telescope. MoS2 has been determined as the solid lubricant of choice for sensitive mechanisms employed in a number of precision instruments on JWST, including the Near Infrared Spectrograph (NIRSpec) and the Mid Infrared Instrument (MIRI) [50,57]. Critical to the choice of MoS2 as the preferred solid lubricant for these high-precision instruments was the fact that it preserves its lubricative properties down to cryogenic temperatures (which include 30 K, the temperature around which JWST will be operating) [58] and the high uniformity with which it can be deposited on precision bearings employed in the instruments at sub-micron thicknesses, ensuring stable operation.…”

Section: Tribological Applications Of Mos2mentioning

confidence: 99%

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Solid Lubrication with MoS2: A Review

et al. 2019

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Molybdenum disulfide (MoS2) is one of the most broadly utilized solid lubricants with a wide range of applications, including but not limited to those in the aerospace/space industry. Here we present a focused review of solid lubrication with MoS2 by highlighting its structure, synthesis, applications and the fundamental mechanisms underlying its lubricative properties, together with a discussion of their environmental and temperature dependence. An effort is made to cover the main theoretical and experimental studies that constitute milestones in our scientific understanding. The review also includes an extensive overview of the structure and tribological properties of doped MoS2, followed by a discussion of potential future research directions.MoS2 belongs to the family of layered two-dimensional transitional metal dichalcogenides (TMDs). Like graphite and hexagonal boron nitride, its crystal structure consists of covalently bonded sheets, which form stacks that are held together only by weak Van der Waals interactions [16]. It occurs naturally as the mineral molybdenite, an important Mo ore. Due to the strong bonding inplane and weak bonding out-of-plane, mechanical and other properties are highly anisotropic [17], and the stacks can be easily sheared. Single-layer or few-layer (i.e. 2D) MoS2 (analogous to graphene) can be produced and studied individually [18].MoS2 has several different possible structures (polytypes), depending on the bonding within the sheets and the stacks of the sheets. While graphite has a single plane of atoms per sheet, in MoS2 each sheet consists a plane of Mo atoms sandwiched between two planes of S atoms. The single-sheet structure can feature trigonal prismatic coordination around Mo, which is the semiconducting 1H ("hexagonal") structure, or octahedral bonding, which is the metallic 1T ("trigonal") phase. 1H and the ideal 1T each have 3 atoms (MoS2) per unit cell ( Figure 1); however, theoretical calculations with density-functional theory (DFT)[19] and X-ray diffraction (XRD) experiments [20] have shown that in fact 1T is unstable with respect to distortions. The most commonly reported structure is a 3× 3 distortion that triples the unit cell, known as the 1T′ phase [21].Each single-sheet structure can be stacked into a crystal where the next sheet is exactly above the preceding one (AA stacking), producing the 1H, 1T, and 1T′ polytypes. The naturally occurring polytypes in molybdenite, however, are only based on the 1H sheet, and show more complicated stacking [9]. The more common is the 2H structure with 2 sheets per cell in AB stacking, where an S atom in one layer is above an Mo atom in the layer below [22,23]. The less common 3R ("rhombohedral") structure has 3 sheets per cell with ABC stacking [22,24]. These structures are shown in Figure 1. Mo-S bond lengths are around 2.4 Å for all polytypes [25]. DFT calculations show only very small energy differences between the 2H and 3R phases [25]. This insensitivity to stacking, and the low surface energy for 2H-MoS2 of 47 mJ/m 2 =...

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Section: Polytypementioning

confidence: 99%

Section: Tribological Applications Of Mos2mentioning

confidence: 99%

Solid Lubrication with MoS2: A Review

et al. 2019

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“…In addition it minimizes the number of harnesses from the warm electronics to the cryogenic part of the instrument and thus the conducted heat load. The chosen wheel design guarantees high precision and highly reliable positioning of the optical elements while using low driving power -in particular zero power during science operation -and therefore low heat injection into the cooled MIRI instrument (more details can be found in Krause et al 2010).…”

Section: Mechanism Designmentioning

confidence: 99%

The Mid-Infrared Instrument for JWST, II: Design and Build

Wright,

Goodson

et al. 2015

Preprint

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The Mid-InfraRed Instrument (MIRI) on the James Webb Space Telescope (JWST) provides measurements over the wavelength range 5 to 28.5 µm. MIRI has, within a single 'package', four key scientific functions: photometric imaging, coronagraphy, single-source low-spectral resolving power (R ∼ 100) spectroscopy, and medium-resolving power (R ∼ 1500 to 3500) integral field spectroscopy. An associated cooler system maintains MIRI at its operating temperature of <6.7 K. This paper describes the driving principles behind the design of MIRI, the primary design parameters, and their realisation in terms of the 'as-built' instrument. It also describes the test programme that led to delivery of the tested and calibrated Flight Model to NASA in 2012, and the confirmation after delivery of the key interface requirements.

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“…The filter wheel mechanism is usually a single point of failure in the equipment, so the design of mechanism with simple structure, long life, high stiffness and high reliability is the premise to ensure the clear observation of exoplanets in orbit. Corresponding author: Mingming Xu , xmm4544@sina.com The James Webb Space Telescope (JWST) is equipped with a low-temperature filter wheel mechanism [3][4] and a near infrared channel cryogenic filter wheel [5] , which are both center driving structure. Although they have been applied to mid-wave infrared spectrum and near-infrared spectrum successfully, their filter diameters are small and the structure size is big.…”

Section: Introductionmentioning

confidence: 99%

Design and dynamics experiment of filter wheel mechanism of space coronagraph

Guo¹,

Dou²,

Xu³

et al. 2023

Ninth Symposium on Novel Photoelectronic Detection Technology and Applications

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High-precision cryogenic wheel mechanisms of the JWST/MIRI instrument: performance of the flight models

Cited by 12 publications

References 0 publications

Solid Lubrication with MoS2: A Review

Solid Lubrication with MoS2: A Review

The Mid-Infrared Instrument for JWST, II: Design and Build

Design and dynamics experiment of filter wheel mechanism of space coronagraph

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