The cosmic smash-up fractured rocks, opening up spaces and warm habitats for microbes to move in.

But now scientists believe they have unearthed a piece of the second space orb, boosting the theory of a major smash-up between two galactic travellers.

Witnessing their clashing spectacle of attraction and repulsion upsets and confuses, like slowing to rubberneck an awful three-car smash-up on the Hollywood Freeway.