A spacecraft which launched in 2023 with Irish input, is doing a gravity-assisted flyby of the planet Venus tomorrow on its way to explore if the conditions for life exist on Jupiter's moons.
Dr Caitriona Jackman, a planetary scientist at the Dublin Institute for Advanced Studies (DIAS), is head of the DIAS magnetospheres group contributing to the Juice (Jupiter Icy Moons Explorer) mission of the European Space Agency (ESA).
"There's some really exotic moons at Jupiter, and we have strong evidence from previous missions to suggest that they have icy crusts," Dr Jackman said.
"Underneath the icy crust there's a subsurface ocean of liquid water. It's a case of whether some extreme life forms can thrive in those oceans."
Juice will fly around Venus to gain velocity for its ongoing trip to Jupiter, using its main antenna as a shield to protect onboard instruments from the heat of the inner solar system sun.
It will not collect data from Venus as the craft is designed for operating in the colder, outer solar system where the moons of Jupiter are located.
"At first it may seem counterintuitive that we have to head towards the sun to get to Jupiter, but it's a necessary part of the fuel-saving trajectory," Dr Jackman said. Two further flybys of the Earth are scheduled for next year and 2029.
The Irish group are involved in two of the spacecraft's scientific instruments. The Plasma Wave Investigation (PWI) instrument will measure the properties of gases around Jupiter and its moons, while the PEP (Particle Environment Package) instrument will measure neutral and charged particles in the Jupiter system.
"They're going to help us to understand what is the extent of any oceans underneath the surface of these moons, and, crucially, what is the salinity or saltiness of these oceans," Dr Jackman said.
The DIAS group will also be investigating "plumes" - geyser-like eruptions similar to what can be seen in Iceland.
"The plumes are fantastic if you can catch them, because then you can fly the spacecraft through them, and sniff and taste what's in the plume, giving you quasi-direct access to the ocean underneath," Dr Jackman said.
Juice aims to determine if the conditions that could support life exist beneath the crusts of Jupiter's large icy moons: Ganymede, Callisto and Europa - three of the planet's 95 recognised moons.
These moons have been selected because scientists believe warmed oceans exist beneath their icy surfaces, with the chemistry for life.
The mission will gather data on the thickness of each moon's icy crusts, the depth of their hidden oceans, and the salinity of the waters - all key factors in assessing whether they could hold life.
The other DIAS scientists involved in Juice are Dr Hans Huybrighs and Dr Mika Holmberg.
Juice is due to arrive at Jupiter in 2031 just months before Nasa's Europa Clipper Mission - the first time that two space missions have simultaneously explored the Jovian system. This reflects growing global interest in assessing the habitability of outer solar system moons - a priority identified in ESA's Voyage 2050 programme.