The Mid-infrared Instrument for JWST and Its In-flight Performance

The Mid-Infrared Instrument (MIRI) extends the reach of the James Webb Space Telescope (JWST) to 28.5 μm. It provides subarcsecond-resolution imaging, high sensitivity coronagraphy, and spectroscopy at resolutions of λ/Δλ ∼ 100-3500, with the high-resolution mode employing an integral field unit to provide spatial data cubes. The resulting broad suite of capabilities will enable huge advances in studies over this wavelength range. This overview describes the history of acquiring this capability for JWST. It discusses the basic attributes of the instrument optics, the detector arrays, and the cryocooler that keeps everything at approximately 7 K. It gives a short description of the data pipeline and of the instrument performance demonstrated during JWST commissioning. The bottom line is that the telescope and MIRI are both operating to the standards set by pre-launch predictions, and all of the MIRI capabilities are operating at, or even a bit better than, the level that had been expected. The paper is also designed to act as a roadmap to more detailed papers on different aspects of MIRI

The Science Performance of JWST as Characterized in Commissioning

This paper characterizes the actual science performance of the James Webb Space Telescope (JWST), as determined from the six month commissioning period. We summarize the performance of the spacecraft, telescope, science instruments, and ground system, with an emphasis on differences from pre-launch expectations. Commissioning has made clear that JWST is fully capable of achieving the discoveries for which it was built. Moreover, almost across the board, the science performance of JWST is better than expected; in most cases, JWST will go deeper faster than expected. The telescope and instrument suite have demonstrated the sensitivity, stability, image quality, and spectral range that are necessary to transform our understanding of the cosmos through observations spanning from near-earth asteroids to the most distant galaxies.Comment: 5th version as accepted to PASP; 31 pages, 18 figures; https://iopscience.iop.org/article/10.1088/1538-3873/acb29

The James Webb Space Telescope Mission

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure

The Preliminary Thermal Design for the SPEQTRE CubeSat

Coraline Dalibot, UKRI STFC RAL SPACE, GBSamuel Tustain, UKRI STFC RAL SPACE, GBICES107: Thermal Design of Microsatellites, Nanosatellites, and PicosatellitesThe proceedings for the 2020 International Conference on Environmental Systems were published from July 31, 2020. The technical papers were not presented in person due to the inability to hold the event as scheduled in Lisbon, Portugal because of the COVID-19 global pandemic.CubeSats are now experiencing a strong demand for advanced scientific and technological performances which is increasing the value of heritage, accessible thermal flight data and high readiness technologies, on top of miniaturization and modularity challenges. This compels us to pay extra attention to their thermal management. In addition, the procedures and guidelines typically used for the thermal design of space systems are often inadequate for CubeSats, which result in over or under-sized thermal control systems. The Space Photon Entanglement Quantum Technology Readiness Experiment (SPEQTRE) CubeSat is a mission to demonstrate quantum key distribution which can secure communications between space systems and Earth ground segments. This project emerged from an international collaboration between RAL Space, part of the UK Science and Technology Facilities Council (STFC), and the Centre for Quantum Technologies (CQT) hosted by the National University of Singapore (NUS). Whilst CQT is responsible for the quantum source on the satellite and quantum receiver on the ground station, RAL Space is responsible for the optical payload, the spacecraft platform and the ground station at Chilbolton (UK). This paper describes how we are approaching the thermal design for the overall SPEQTRE CubeSat mission and how we are meeting the challenges and opportunities of supporting collaborator furnished systems. Bringing together CubeSat and quantum communication technologies requires stringent specifications. In addition, the required thermal management has a major impact on the scientific performance. The main thermal challenges are the thermal environment in Low Earth Orbit (LEO), the high power density, the required thermal stability and uniformity, and the thermal design flexibility. Launch is scheduled for Q1/Q2 2023

Developing a Standardized Approach for the Thermal Analysis of Spacecraft Electronics

Tom Mccarron, RAL SpaceSamuel Tustain, RAL SpaceICES105: Thermal Standards and Design/Development PracticesThe 48th International Conference on Environmental Systems was held in Albuquerque, New Mexico, USA on 08 July 2018 through 12 July 2018.RAL Space, part of the UK Science and Technology Facilities Council (STFC), design, build, and test a range of ground and space-based instrumentation and equipment. Among these projects are those that require the detailed thermal analysis of sophisticated spacecraft electronics, which must capture the hot spots caused by high power dissipating components on the printed circuit boards. Two recent examples at RAL Space involve the analysis of electronics for the MetOp Second Generation and the World Space Observatory programs. As the power density of electronics is expected to continue increasing, the accurate thermal modelling of such systems is of growing importance. However, there remains a significant uncertainty in many aspects of the analysis, such as the conductive coupling of individual components to boards and a difficulty in characterizing the thermal properties of the boards themselves. Empirical data gathered during recent projects suggests that the current approach may be too conservative. However, in the interests of thermal model accuracy and stability, it is important to avoid over-complex modelling methods. The authors have undertaken a critical review of the RAL Space approach to this problem in order to produce a formal procedure in line with the ISO9001 standards that the organization is accredited to. This procedure aims to present the best practice, and outlines a recommended set of guidelines to be followed when performing such analyses. The purpose of this paper is to discuss the findings of the team tasked with producing this document, review available literature published in this field, and justify the final guidelines adopted within the procedure. Also examined are the unresolved issues surrounding the modelling of electronics and the mitigating actions suggested to reduce future design risk

The Conceptual Design and Analysis of the Cryogenic Test Rig for the ARIEL Payload Module

Ediz Tunarli, Science and Technology Facilities Council, Rutherford Appleton Laboratory, GBSamuel Tustain, Science and Technology Facilities Council, Rutherford Appleton Laboratory, GBICES108: Thermal Control of Cryogenic Instruments and Optical SystemsThe proceedings for the 2020 International Conference on Environmental Systems were published from July 31, 2020. The technical papers were not presented in person due to the inability to hold the event as scheduled in Lisbon, Portugal because of the COVID-19 global pandemic.The Atmospheric Remote-Sensing Infrared Exoplanet Large-survey (ARIEL) was selected in March 2018 by ESA as the fourth medium-class mission (M4) in ESA’s Cosmic Vision Programme, due to launch in 2028. During a mission lifetime of 4 years on its orbit around the L2 Lagrange point, ARIEL will explore the chemistry of 1000 exoplanets through precise spectroscopy. The payload for the ARIEL mission is developed by a UK led consortium with participation from 14 ESA member states. RAL Space, part of the UK Science and Technology Facilities Council (STFC), has the main responsibility of the management and coordination of the activities of the ARIEL payload consortium. Another part of STFC, the Cryogenics Group is developing a flight cryocooler for active cooling of the instrument detectors to satisfy these components’ strict temperature requirements. In addition, RAL Space is responsible for the design and manufacture of a cryogenic test rig for the ground testing activities of the ARIEL payload. During its operation in the orbit, the payload will be shaded from the Sun by V-Groove shields mounted to the spacecraft bus and it will have a constant view of deep space. In order to simulate these conditions as much as possible, a target temperature of 20 K is chosen for the shroud panels of the test rig. The design activities are focused on delivering this temperature level while taking into account constraints such as uniformity and cool-down time, with a trade-off performed in order to select the most appropriate method of cooling. The design of the cryogenic test rig is at a conceptual stage and this paper includes the description of the thermal design and analysis activities performed so far

Lessons Learned from the Solar Correlation and Early Flight Thermal Performance of the Solar Orbiter SPICE Instrument

Samuel Tustain, STFC RAL SpaceAlicja Kasjanowicz, STFC RAL SpaceBryan Shaughnessy, STFC RAL SpaceICES101: Spacecraft and Instrument Thermal SystemsThe 50th International Conference on Environmental Systems was held virtually on 12 July 2021 through 14 July 2021.The Spectral Imaging of the Coronal Environment (SPICE) instrument is one of ten instruments comprising the science payload of ESA�s Solar Orbiter mission. Launched in February 2020, and successfully commissioned by July, SPICE was built at the STFC Rutherford Appleton Laboratory and is a high resolution imaging spectrometer operating at extreme ultraviolet wavelengths. With Solar Orbiter ultimately reaching a perihelion of 0.28 AU (corresponding to a solar flux of approximately 17 kW per square metre or 13 solar constants), the thermal performance of SPICE under extreme solar loading is a crucial element of the instrument�s design. The instrument�s primary mirror is of particular importance for managing this solar load; it is designed to reflect ultra-violet wavelengths that are of scientific value whilst being transmissive to visible and infrared wavelengths. This allows a significant portion of the solar energy to pass through the instrument and back into deep space. During thermal balance testing, an intense UV lamp was the best approximation available to provide data for correlating the solar properties of the instrument. The correlation process therefore had to also account for the spectral differences between the UV lamp and the true solar spectrum. This paper will discuss the real world challenges in such a correlation and compare the outcome of the original correlated model with flight data acquired at 0.88 AU and 0.54 AU during the commissioning phase of Solar Orbiter. In particular, the insight gained on designing and modelling instruments for such extreme thermal conditions in deep space will be explored. The approach taken for SPICE will be compared with similar solar missions and lessons learned for future solar missions will be identified

On-orbit Thermal Performance of the JWST Mid-Infrared Instrument

Bryan Shaughnessy, Rutherford Appleton Laboratory (RAL) Space, United KingdomTim Grundy, Rutherford Appleton Laboratory (RAL) Space, United KingdomSamuel Tustain, Rutherford Appleton Laboratory (RAL) Space, United KingdomMireya Etxaluze, Rutherford Appleton Laboratory (RAL) Space, United KingdomBret Naylor, Jet Propulsion Laboratory, USAMark Weilert, Jet Propulsion Laboratory, USAICES202: Satellite, Payload, and Instrument Thermal ControlThe 52nd International Conference on Environmental Systems was held in Calgary, Canada, on 16 July 2023 through 20 July 2023.Authors Bryan M. Shaughnessy(1), Tim Grundy(1), Samuel Tustain(1), Mireya Etxaluze(1) Bret Naylor(2) and Mark Weilert(2). 1 RAL Space, STFC Rutherford Appleton Laboratory, UK 2 Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA Abstract The James Webb Space Telescope (JWST) observatory was launched on the 25th December 2021. This was followed by a commissioning phase of about six months, where the observatory deployed to its final configuration and transferred to its L2 orbit location, whilst cooling science components and instruments down to their cryogenic operating temperatures. The Mid-Infrared Instrument (MIRI) is one of four scientific instruments on the JWST observatory. It provides unique capabilities to probe the deeply dust-enshrouded regions of the universe, investigating the history of star formation both near and far. The MIRI is the coldest instrument on the observatory. Its thermal design is driven by requirements to cool an Optics Module (OM) to below 16 K and detectors within this to below 7 K with a stability of <10 mK over 1000 seconds. The OM is accommodated within the passively cooled Integrated Science Instrument Module (ISIM). The instrument temperatures are achieved by a combination of thermal isolation from the ISIM and active cooling by a dedicated cryocooler. This paper summarises briefly the thermal design and pre-launch thermal verification of the instrument. It goes on to report the MIRI thermal performance through the commissioning phase, and concludes with lessons that can be applied to future similar missions

Uncovering the S=1/2 Kagome Ferromagnet within a Family of Metal-Organic Frameworks

[Image: see text] Kagome networks of ferromagnetically or antiferromagnetically coupled [Image: see text] magnetic moments represent important models in the pursuit of a diverse array of novel quantum and topological states of matter. Here, we explore a family of Cu(2+)-containing metal–organic frameworks (MOFs) bearing [Image: see text] kagome layers pillared by ditopic organic linkers with the general formula Cu(3)(CO(3))(2)(x)(3)·2ClO(4) (MOF-x), where x is 1,2-bis(4-pyridyl)ethane (bpe), 1,2-bis(4-pyridyl)ethylene (bpy), or 4,4′-azopyridine (azpy). Despite more than a decade of investigation, the nature of the magnetic exchange interactions in these materials remained unclear, meaning that whether the underlying magnetic model is that of an [Image: see text] kagome ferromagnet or antiferromagnet is unknown. Using single-crystal X-ray diffraction, we have developed a chemically intuitive crystal structure for this family of materials. Then, through a combination of magnetic susceptibility, powder neutron diffraction, and muon-spin spectroscopy measurements, we show that the magnetic ground state of this family consists of [Image: see text] ferromagnetic kagome layers that are coupled antiferromagnetically via their extended organic pillaring linkers

Uncovering the S=12 Kagome Ferromagnet within a Family of Metal–Organic Frameworks

Kagome networks of ferromagnetically or antiferromagnetically coupled S=12 magnetic moments represent important models in the pursuit of a diverse array of novel quantum and topological states of matter. Here, we explore a family of Cu2+-containing metal–organic frameworks (MOFs) bearing S=12 kagome layers pillared by ditopic organic linkers with the general formula Cu3(CO3)2(x)3·2ClO4 (MOF-x), where x is 1,2-bis­(4-pyridyl)­ethane (bpe), 1,2-bis­(4-pyridyl)­ethylene (bpy), or 4,4′-azopyridine (azpy). Despite more than a decade of investigation, the nature of the magnetic exchange interactions in these materials remained unclear, meaning that whether the underlying magnetic model is that of an S=12 kagome ferromagnet or antiferromagnet is unknown. Using single-crystal X-ray diffraction, we have developed a chemically intuitive crystal structure for this family of materials. Then, through a combination of magnetic susceptibility, powder neutron diffraction, and muon-spin spectroscopy measurements, we show that the magnetic ground state of this family consists of S=12 ferromagnetic kagome layers that are coupled antiferromagnetically via their extended organic pillaring linkers