Speaker
Description
JUICE (JUpiter ICy moons Explorer) is the first large-class mission of ESA’s Cosmic Vision 2015–2025 program. It was launched in April 2023 and will arrive at Jupiter in July 2031. After a 3.4-year tour of the Jupiter system, JUICE will enter into a dedicated orbital phase around Ganymede for about one year. The primary goals of the mission are to investigate Jupiter’s complex magnetosphere and atmosphere, and to address the formation, evolution, and potential habitability of icy worlds by observing the different envelopes of the Galilean moons Ganymede, Europa, and Callisto.
One of the four remote sensing instruments on the JUICE payload is the Moons And Jupiter Imaging Spectrometer (MAJIS), a visible and infrared imaging spectrometer. In this presentation, we will describe the MAJIS instrument architecture and its high-level technical specifications. It operates using a VISNIR channel (0.5–2.35 μm) and an IR channel (2.28–5.56 μm), each based on a 1024×1024 pixel HgCdTe H1RG detector. The spectral sampling is 3.55–3.87 nm and 5.94–7.18 nm for the VISNIR and IR channels respectively. The instantaneous field of view is 150 μrad, yielding a 30 km wide swath with a maximum spatial resolution of 75 m/pixel at a 500 km altitude. A passive cryogenic optical design shall cool the optical head structure and the VISNIR detector to ~130 K, while the IR focal plane is cooled to ~85 K during scientific operations at Jupiter.
The Main Electronics (ME) unit manages complex onboard processing to ensure operational efficiency. This includes specialized compression units to handle the high data volume generated by the instrument, as well as a dedicated despiking procedure within the Proximity Electronics to maintain less than 1% corrupted pixels per frame caused by high-energy particles in the Jovian environment. Variable integration times, ranging from 100 ms for high-flux regions such as Jovian hot spots to several seconds for low signal observations (rings, exosphere) can be accommodated to these diverse observational conditions.
MAJIS achieves high signal-to-noise performance across its entire spectral range, as demonstrated by in-flight measurements during the initial cruise phase, including the Lunar and Earth gravitational assist in August 2024. Optimized for both close flybys and the stable orbital phase around Ganymede, MAJIS can operate in push-broom or scanning modes, the latter providing motion compensation for high-resolution observations. Ultimately, MAJIS is expected to deliver unprecedented hyperspectral datasets, leveraging these advancements to exceed the data collection rate of the Galileo NIMS instrument by a factor of 10,000.