By Jove: France's instrumental part in study of Jupiter's icy moons

The European Space Agency's ambitious mission called Jupiter Icy Moons Explorer, or JUICE, was launched on 14 April from French Guiana. Its main objective is to study Jupiter and its three icy moons: Ganymede, Europa, and Callisto.

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The JUICE mission was launched on an Ariane 5 rocket from French Guiana. © ESA - S. Corvaja

One of the instruments on board the JUICE spacecraft is called Moons and Jupiter Imaging Spectrometer or MAJIS. It was developed at the Institut d'Astrophysique Spatiale (IAS) which is based in Orsay near Paris.

"The main objective of MAJIS is to map the limits of the surfaces of the three Jupiter moons as well as characterise the atmosphere of Jupiter," IAS's François Poulet who is the principal investigator of MAJIS, told RFI. 

A principal investigator (PI) refers to the lead researcher of a grant project, usually in the sciences, usually in laboratory studies, or in clinical trials. The phrase is also often used as a synonym for "head of the laboratory" or "research group leader".

"The goal is to detect different kinds of species such as ice, minerals and organics, if organics are present on these surfaces," he said.

Speaking about the instrument, Poulet said it took the team more than 10 years to build it. 

"It was quite challenging as being a cryogenic instrument, it has to operate at very cold temperatures. So we needed to control the thermal balance of this instrument. We used a specific radiator to cool it down up to 90 Kelvin (-183 degrees Celsius) especially for the infrared detector," he said.

He added that they also had to take into account the intense radiation in the Jovian environment.

"We also needed to protect all the electronics and some optical elements which are sensitive to radiation," he said.

JUICE, which carries 10 instruments, will enter Jupiter's orbit in 2031. The mission is scheduled to end in September 2035.