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JANUS: The Scientific Camera Onboard the ESA Juice Mission and It’s Commissioning

Presentation #311.07 in the session Future Missions and Instrumentations - Icy Bodies, Exoplanets, Stars (Poster)

Published onOct 23, 2023
JANUS: The Scientific Camera Onboard the ESA Juice Mission and It’s Commissioning

The Jupiter Icy Moons Explorer (JUICE) mission is the first Large (L-class) mission selected for the European Space Agency (ESA) Cosmic Vision 2015-2025 program. It is devoted to exploring the Jupiter system and investigating its icy Galilean satellites Europa, Ganymede and Callisto [Grasset et al., (2013)]. JUICE has been succesfully launched on 14 April 2023 from Europe’s Spaceport in Kourou, French Guiana, on an Ariane 5 launcher and, after its 8 years journey throughout the inner Solar System, it will reach the Jupiter system in July 2031. During its nominal science phase, JUICE is planned to spend many months orbiting around Jupiter, performing fly-bys of Europa, Ganymede and Callisto, and finally conducting an orbital tour of Ganymede.

JUICE carries 10 state-of-the-art instruments, comprising the most powerful remote sensing, geophysical and in situ payload suite ever flown to the outer Solar System. Among those, JANUS (Jovis Amorum ac Natorum Undique Scrutator) is the scientific optical camera system [Palumbo et al., (2014)]. Its design has been optimised, according to JANUS’ scientific requirements, for observations of a wide range of targets, from Jupiter’s atmosphere, to solid satellite surfaces and their exospheres, rings, and transient phenomena like lightning.

JANUS is a modified Ritchey-Chrétien telescope. It has a nominal focal length of 467 mm, an effective entrance pupil diameter of 103.6 mm, a FoV of 1.72°x1.29° and a 2000x1504 pixel CMOS sensor with a pixel dimension of 7 µm. In addition, a filter wheel with 13 filters allows JANUS to obtain multi-spectral images in the 340-1080 nm wavelength range. This camera provides images of the targets with a scale of 7.5 m/pix at a distance of 500 km. Such characteristics will allow to observe the surfaces of the icy satellites with a spatial resolution ranging from 400 m to 3 m for Europa, Ganymede and Callisto. In addition, Jupiter and other targets, e.g. Io, small moons and rings, will be observed with a resolution from few km to tens of km.

On 16-18 May 2023, about one month after launch, JANUS went through its in-flight commissioning during the Near-Earth Commissioning Phase. A series of activities were carried out to verify that each instrument subsystem is fully functional after launch and for in-flight instrument performance characterization. A first analysis shows that JANUS is fully functional and its performances are as expected.

Here we will present the instrument itself, the results from its commissioning activities and JANUS’ upcoming scientific mission.

Acknowledgments: The activity has been realized under the ASI-INAF contract 2023-06-HH.0.

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