BIO
Dr Olivier Witasse
Witasse is a planetary scientist at the European Space Agency. He is the project scientist for the ESA’s upcoming JUpiter ICy moons Explorer (JUICE) spacecraft, due to launch in April 2023 and arrive at Jupiter in 2031. Witasse has worked on a plethora of ESA-related space exploration missions, including Mars Express, Venus Express, Cassini-Huygens, the ExoMars Trace Gas Orbiter and Chandrayaan-1.
How have Ganymede, Callisto and Europa – the moons JUICE will be visiting – sustained subsurface oceans despite being so far away from the Sun? Why haven’t they frozen over?
They are called ‘icy moons’ because they are made of frozen ice. But there is a mechanism inside the moons which generates heat, and then the ice can melt and become liquid. The question is, how is the heat generated inside? Here we have two possible reasons: one answer is that because the moons are actually large, there are – like on Earth – some radioactive elements. Inside Earth, for example, there is heat
