SOME planets revolve close enough to their suns to support human-like life.
Some either once had liquid water, or possibly harbour it under their surfaces.
And now Saturn – or more specifically, one of its moons – has shown that Earth doesn’t have a monopoly on oxygen either.
A new report published in Geophysical Research Letters describes how Cassini – the global initiative satellite that’s been orbiting the ringed planet since 2004 – has detected a thin layer of oxygen around icy moon Dione.
The discovery was made two years ago, but these things have to be verified before they can be published, so here it is – heat, water and oxygen all occurring in the universe somewhere other than Earth.
But before you get too excited about that interplanetary move, there’s a few things to consider.
One is that the layer of oxygen around Dione is too thin to be considered an atmosphere, so for now, scientists are calling it an exosphere.
It’s about the equivalent of oxygen on Earth if you were breathing it 500km up.
And as far as the surface of Dione itself goes, there’s no liquid water, which means you’d be relying on a a kind of intergalactic watercooler top-up service, or, if you’re Bear Grylls, drinking your own wee.
The important thing for Team Cassini is the discovery supports a theory that claims oxygen is present in some form on most of the moons around Saturn and Jupiter.
Add that to the fact that some of those moons do indeed support bodies of liquid water and you have a stronger case for finding life in some form.
Enceledus, for example, is another Saturnian moon which is thought to host a liquid ocean beneath its surface.
The oxygen on Dione is thought to be present on Dione due to highly charged particles from Saturn’s radiation belt splitting its ice water into oxygen and hydrogen.
For the now, what it all means is the European Space Agency folk can push for more money to launch an orbiter to Jupiter’s icy moons and begin drilling for life beneath the surface.
Europa is the most likely candidate, although a co-author of the Dione study, Andrew Coates, offers a tantalising future scenario for Titan, Saturn’s largest moon.
With its nitrogen and methane atmosphere, he tells the BBC, “it may be an Earth waiting to happen as the outer Solar System warms up”.