In a few hours, a spacecraft should blast-off from Florida on the hunt for signs of alien life.

The spaceship is the largest ever built to visit a planet and has a long journey ahead.
Its destination is Europa, a deeply-mysterious moon orbiting the distant planet Jupiter.

"If we discover life so far away from the Sun, it would imply a separate origin of life to the Earth," says Mark Fox-Powell, a planetary microbiologist [...].

"That is hugely significant, because if that happens twice in our solar system, it could mean life is really common," [...]

[Europa's] icy crust is up to 25km thick, and sloshing beneath, there could be a vast saltwater ocean. There may also be chemicals that are the ingredients for simple life.

"We are searching for the potential for habitability and you need four things - liquid water, a heat source, and organic material. Finally those three ingredients need to be stable over a long enough period of time that something can happen," [...]