Scientists say they have detected phosphorus, a key building block for life, in water samples from a moon of Saturn.

Enceladus is about 500 kilometers in diameter and orbits Saturn -- the second largest planet in the solar system.

Water containing organic compounds had previously been found beneath the surface of Enceladus, but its composition was unknown.

The international team, including Japanese, US and European researchers, used observation data collected by the Cassini spacecraft that operated until 2017.

They examined water ejected into space from the subsurface ocean of Enceladus.

The researchers say the phosphorus concentrations in the water are much higher than those of Earth's oceans. The element is an essential ingredient of DNA and cell membranes.

They say large amounts of phosphorus contained in minerals likely seeped into the water as a result of chemical reactions.

Similar reactions are believed to occur in other astronomical bodies in the solar system.

The research team says the discovery of phosphorus in water from Enceladus could mean that life exists beyond Earth.

Professor Sekine Yasuhito of the Tokyo Institute of Technology says astronomical bodies outside the solar system universally have environments that are rich in phosphorus and nitrogen. He says species that are similar to life on Earth may exist there.