Earth-type life 'rarer than we think'
Earth-type life may be more rare and precious than is commonly thought, according to a study that hints at a cosmic lack of phosphorus.
The element is vital to energy storage and transfer in cells, and is part of the chemical backbone of DNA. Phosphorus is created in supernovae, massive stars exploding at the end of their lives.
But research suggests typical supernovae may not provide the conditions needed for forging the element. Earth may be unusually lucky, because it happened to be close enough to the "right" kind of supernova.
Astronomer Dr Jane Greaves, from the University of Cardiff, said: "The route to carrying phosphorus into new-born planets looks rather precarious.
"We already think only a few phosphorus-bearing minerals that came to the Earth, probably in meteorites, were reactive enough to get involved in making proto-biomolecules.
"If phosphorus is sourced from supernovae, and then travels across space in meteoritic rocks, I'm wondering if a young planet could find itself lacking in reactive phosphorus because of where it was born?"
The evidence comes from observations of two supernova "remnants", Cassiopeia A (Cas A) and the famous Crab Nebula.