High Frequency Instrument

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High Frequency Instrument

The High Frequency Instrument was a cryogenic bolometer array on the Planck mission operated by the European Space Agency and developed by a consortium including Centre National d'Études Spatiales, National Aeronautics and Space Administration, and Jet Propulsion Laboratory. It measured microwave and submillimetre sky emission across several bands to map cosmic microwave background anisotropies, Galactic interstellar medium, and extragalactic sources during an operational phase overlapping with missions such as Wilkinson Microwave Anisotropy Probe and programs by Herschel Space Observatory. Its dataset contributed to cosmological analyses alongside results from BICEP2, South Pole Telescope, and Atacama Cosmology Telescope.

Overview

The instrument complemented the Low Frequency Instrument on Planck with high-frequency coverage at 100–857 GHz, enabling cross-calibration with COBE, WMAP, and Herschel Space Observatory datasets and informing parameter estimation used by teams at Max Planck Institute for Astrophysics, California Institute of Technology, Institut d'Astrophysique Spatiale, and University of Cambridge. It operated from the Lagrange point L2 platform, benefiting from thermal stability exploited by missions such as Gaia and James Webb Space Telescope. Science goals aligned with probes from Sloan Digital Sky Survey and surveys by Very Large Array for multifrequency source identification.

The focal plane housed arrays of spider-web and polarization-sensitive bolometers developed by groups at University of Cardiff, University of Manchester, Institut d'Astrophysique Spatiale, and NASA Goddard Space Flight Center, coupled to feedhorns and filters patterned by contractors including Airbus Defence and Space and tested at facilities such as Centre Spatial de Toulouse. The instrument relied on a sorption and dilution cryostat providing sub-kelvin stages similar to systems used on Herschel Space Observatory and prototypes from European Southern Observatory partnerships; readout electronics used SQUID amplifiers and multiplexing designs informed by work at National Institute of Standards and Technology and Laboratory for Space Research teams. The optical chain incorporated reflectors aligned to the Planck primary mirror geometry constrained through metrology from European Southern Observatory and manufactured by industrial partners in collaboration with Thales Alenia Space.

Primary objectives included high-resolution mapping of the Cosmic microwave background anisotropies, measurement of foregrounds such as thermal dust emission in the Milky Way, and detection of Sunyaev–Zel'dovich signals from galaxy clusters catalogued by ROSAT, XMM-Newton, and Chandra X-ray Observatory. Observational programs targeted cosmological parameters tested against models by teams at Princeton University, Harvard-Smithsonian Center for Astrophysics, and Institut d'Astrophysique de Paris while supporting studies of magnetic fields in Orion Nebula and Magellanic Clouds alongside polarization surveys comparable to those from BLASTPol and SPIDER (balloon experiment). Cross-correlation analyses involved datasets from Sloan Digital Sky Survey, Two Micron All Sky Survey, and Herschel Space Observatory to separate astrophysical components.

Calibration pipelines used celestial calibrators like Jupiter and the Cosmic microwave background dipole measured by COBE and WMAP, with instrument characterization performed by teams at European Space Agency, Jet Propulsion Laboratory, and Institut d'Astrophysique Spatiale. Data processing and mapmaking leveraged algorithms developed at Max Planck Institute for Astrophysics, University of British Columbia, and CERN-linked computing centers, incorporating beam reconstruction, time-ordered data cleaning, and component separation methods such as those advanced by researchers at Laboratoire AIM and Oxford University. Systematic error analysis referenced measurements from ground campaigns at Observatoire de Meudon and cross-validation with external catalogs including Planck Catalogue of Compact Sources.

The instrument achieved noise and angular resolution levels that improved cosmological constraints published by consortia including Planck Collaboration and analyzed by groups at University of Cambridge, Princeton University, and Institut d'Astrophysique de Paris. Key results influenced estimates of the Hubble constant when compared with local measurements from Hubble Space Telescope teams and contributed to parameter tensions discussed in the context of analyses by BICEP2, South Pole Telescope, and Atacama Cosmology Telescope. Foreground maps informed studies of Galactic structure in the Perseus Arm and extragalactic source catalogs cross-matched with Sloan Digital Sky Survey, Two Micron All Sky Survey, and follow-up campaigns at Atacama Large Millimeter Array.

Integration work occurred at industrial sites in collaboration with institutions such as Thales Alenia Space, Airbus Defence and Space, and research laboratories including Institute of Space Astrophysics and Centre National d'Études Spatiales with flight acceptance testing coordinated by European Space Agency teams and mission operations by the European Space Operations Centre. Scientific operations interfaced with data centers at Max Planck Institute for Astrophysics, Jet Propulsion Laboratory, and national archives like European Space Agency Science Archive Facility to support legacy science comparable to archives from Herschel Space Observatory and Gaia; follow-up observations were conducted using facilities including Atacama Large Millimeter Array and Very Large Array.

Category:Spacecraft instruments