arXiv subjects

A. Murk

Publications and source records attributed to A. Murk.

3 recordsLinked to original sources

arXiv2026

Juice-SWI during the Lunar-Earth-Gravity-Assist (LEGA) - Part 2: Instrument operations

The Jupiter Icy Moons Explorer (Juice) embarked in 2023 on a 8-year interplanetary journey to Jupiter and its icy moons. The Submillimetre Wave Instrument (SWI) is one of the ten science instruments aboard the spacecraft. SWI is a sophisticated and first-of-its-kind payload visiting the outer solar system, featuring dual-band tunable receivers, two independent pointing mechanisms, and spectrometers capable of high resolution (up to a resolving power of 10^{7}). It is designed to support the diverse science objectives of the Juice mission targeting Jupiter's middle atmosphere, icy-moon's exospheres as well as near sub-surface thermophysical properties. For this purpose the Juice mission adopts a complex trajectory tour within the Jovian system, which further necessitates a sophisticated, mission-driven operations concept for SWI. This presents significant planning, operations and commanding challenges which are described in this paper in the context of the Lunar and Earth Gravity Assist (LEGA). After the development and ground calibration of the instrument, the SWI Team has designed a comprehensive calibration strategy applicable during the Cruise Phase of Juice. Among the various opportunities for calibration, including the Near-Earth Commissioning Phase and more than ten Payload Checkout Windows, the LEGA offers the means not only to improve the calibration of the instrument, but also to validate the operational strategy of future icy moon flybys.

astro-ph.EP↗

arXiv2020

Wideband 67-116 GHz receiver development for ALMA Band 2

ALMA has been operating since 2011, but has not yet been populated with the full suite of intended frequency bands. In particular, ALMA Band 2 (67-90 GHz) is the final band in the original ALMA band definition to be approved for production. We aim to produce a wideband, tuneable, sideband-separating receiver with 28 GHz of instantaneous bandwidth per polarisation operating in the sky frequency range 67-116 GHz. Our design anticipates new ALMA requirements following the recommendations in the 2030 ALMA Development Roadmap. The cryogenic cartridge is designed to be compatible with the ALMA Band 2 cartridge slot, where the coldest components -- the feedhorns, orthomode transducers, and cryogenic low noise amplifiers -- operate at a temperature of 15 K. We use multiple simulation methods and tools to optimise our designs for both the passive optics and the active components. The cryogenic cartridge interfaces with a room temperature cartridge hosting the local oscillator (LO) and the downconverter module. This warm cartridge is largely based on GaAs semiconductor technology and is optimised to match the cryogenic receiver bandwidth with the required instantaneous LO tuning range. Our collaboration has designed, fabricated, and tested multiple technical solutions for each of the components, producing a state-of-the-art receiver covering the full ALMA Band 2 & 3 atmospheric window. The receiver is suitable for deployment on ALMA in the coming years, and is capable of dual-polarisation, sideband-separating observations in intermediate frequency bands spanning 4-18 GHz, for a total of 28 GHz on-sky bandwidth per polarisation channel. We conclude that the 67-116 GHz wideband implementation for ALMA Band 2 is now feasible, and this receiver is a compelling instrumental upgrade that will enhance observational capabilities and scientific reach.

astro-ph.IM↗

arXiv2018

Wideband 67-116 GHz cryogenic receiver development for ALMA Band 2

The Atacama Large Millimeter/sub-millimeter Array (ALMA) is already revolutionising our understanding of the Universe. However, ALMA is not yet equipped with all of its originally planned receiver bands, which will allow it to observe over the full range of frequencies from 35-950 GHz accessible through the Earth's atmosphere. In particular Band 2 (67-90 GHz) has not yet been approved for construction. Recent technological developments in cryogenic monolithic microwave integrated circuit (MMIC) high electron mobility transistor (HEMT) amplifier and orthomode transducer (OMT) design provide an opportunity to extend the originally planned on-sky bandwidth, combining ALMA Bands 2 and 3 into one receiver cartridge covering 67-116 GHz. The IF band definition for the ALMA project took place two decades ago, when 8 GHz of on-sky bandwidth per polarisation channel was an ambitious goal. The new receiver design we present here allows the opportunity to expand ALMA's wideband capabilities, anticipating future upgrades across the entire observatory. Expanding ALMA's instantaneous bandwidth is a high priority, and provides a number of observational advantages, including lower noise in continuum observations, the ability to probe larger portions of an astronomical spectrum for, e.g., widely spaced molecular transitions, and the ability to scan efficiently in frequency space to perform surveys where the redshift or chemical complexity of the object is not known a priori. Wider IF bandwidth also reduces uncertainties in calibration and continuum subtraction that might otherwise compromise science objectives. Here we provide an overview of the component development and overall design for this wideband 67-116 GHz cryogenic receiver cartridge, designed to operate from the Band 2 receiver cartridge slot in the current ALMA front end receiver cryostat.

astro-ph.IM↗