The Submillimetre Wave Instrument on JUICE

2015

The Submillimetre Wave Instrument (SWI) is being developed for the Jupiter Icy moons Explorer (JUICE) mission of the European Space Agency (ESA). In this paper we give an overview of the 530 GHz to 625 GHz receiver unit of SWI and present the first noise temperature measurements covering the complete receiver bandwidth at room temperature operation. In this context we will point out the difficulties with the highly variable local oscillator power within the bandwith, which needs a careful tuning of the multiplier bias voltages in order to optimize the noise temperature and to avoid damage of the mixers. In addition we show initial results at cold temperature operation. Furthermore we will present a first stability measurement showing the temperature dependence of the receiver gain at room temperature operation.

2019

The upcoming Submillimeter Wave Instrument on the JUICE spacecraft is a passive radiometer/spectrometer instrument with two heterodyne receivers which are independently tunable in the frequency bands 530 to 625 GHz and 1080 to 1275 GHz. It will study Jupiter’s atmosphere as well as the atmospheres and surface properties of the Galilean moons. This work presents the results of first radiometric tests with a prototype of the 600 GHz receiver. In this context, the baseline ripples caused by the internal calibration target have been characterized using two conical prototypes with a linear and an exponential absorber coating profile. A significant reduction of the baseline ripple amplitude has been measured with the target having the exponential cone profile. The spectroscopic baseline has been characterized for various frequency steps when applying frequency switching as an alternative calibration mode. At some operating frequencies a very flat switching baseline has been measured for f...

Planetary and Space Science, 2012

Icarus, 2003

Astronomy & Astrophysics, 2020

Context. We address the issue of remote sensing of the surfaces of Galilean icy moons. We investigate the prospects for retrieval of the physical parameters of the surface of the Jovian icy moons from submillimeter wave radiometry data. Aims. We show that the model parameters could not be completely retrieved from the polarized radiometry data, but some of their combinations can be effectively constrained. Methods. The polarized radiative transfer in lossy porous ice was numerically simulated. A Bayesian maximum likelihood retrieval algorithm was developed and tested on the simulated data in a wide range of variation of the model parameters. The uncertainty of the retrievals was evaluated with the Cramer-Rao bounds. We established the combinations of model parameters that can be effectively constrained from the measured data. Results. We reveal that the effective scatterer size can be reliably constrained for a range of values where the scattering asymmetry parameter uniquely depend...

Planetary and Space Science, 2010

2007

САОПШТЕЊА LV / COMMUNICATIONS LV, 2023

The artistically crafted silver objects made in Užice during the 19th century constitute a treasure that shapes the ecclesiastical visual culture. These objects were made in the workshops of Užice silversmiths whose activity has not been sufficiently studied. At the beginning of the 19th century Užice was the second biggest town in Serbia, after Belgrade, up until the withdrawal of the Ottomans from here. Before the big fire of 1862, over twenty silversmiths worked in the old bazaar of Užice together with numerous journeymen and assistants. The most prominent members of Belgrade’s silversmith guild in the 19th century, such as Nikola Stojisiljević and Teofan Jevtović, are from Užice. The existence of a powerful silversmith guild in Užice is documented by the traces of material culture. Silversmiths Sreten Petrović and Andrija Pejić, whose silver objects have been preserved at churches as well, presented their works at the big 1900 Paris Exposition and so did Nedeljko Vujadinović and Luka Todorović. Liturgical objects made of artistically crafted silver have been collected at Užice’s older Church of Saint Mark from the early 19th century and at the Church of Saint George built during the 1840s. The silverware of Užice churches reflects different social and cultural trends, as well as the economic and cultural transformation of the town.