An essential ingredient for life has been identified in abundant quantities on Jupiter's moon, Europa.
Hydrogen peroxide is used by life forms as fuel - and high concentrations of were spotted in limited areas by the Galileo mission, from 1995 to 2003.
Nasa's Kevin Hand and Mike Brown of the California Institute of Technology used data from the Keck II Telescope to show the compound was far more common than previously thought.
Other ingredients for life, water and elements such as carbon and nitrogen, are already known to exist on Europa which has vast liquid subterranean oceans below sheets of thick ice.
In a NASA statement, Hand said: "Life as we know it needs liquid water, elements like carbon, nitrogen, phosphorus and sulfur, and it needs some form of chemical or light energy to get the business of life done.
"Europa has the liquid water and elements, and we think that compounds like peroxide might be an important part of the energy requirement.
"The availability of oxidants like peroxide on Earth was a critical part of the rise of complex, multicellular life."
Brown added that what is still unknown is how the oceans and the hydrogen peroxide mix.
He said: "The Galileo measurements gave us tantalizing hints of what might be happening all over the surface of Europa, and we've now been able to quantify that with our Keck telescope observations.
"What we still don't know is how the surface and the ocean mix, which would provide a mechanism for any life to use the peroxide."
And it might not be too long before we get to take a closer look - last week the US approved funds to scope out a possible future mission to Europa.
A recent study said that a Europa orbiter was the second-highest priority behind a new $3.5bn mission to place two rovers on Mars.
"The first step in understanding the potential of the outer solar system as an abode for life is a Europa mission with the goal of confirming the presence of an interior ocean, characterizing the satellite’s ice shell, and understanding its geological history."