Life on Mars? Though the debate rages on, a team of UNLV researchers has discovered that phosphate - an essential chemical ingredient for life - may have been more abundant on early Mars than during the emergence of life on Earth.
In a study published recently in Nature Geoscience, doctoral student Christopher Adcock and colleagues created and then dissolved synthetic phosphate-containing minerals similar to those found on Mars. Determining how well the minerals dissolve is key to understanding how readily available the phosphate may have been for life-creating chemical reactions.
"Due to its chemical properties, phosphate is needed for all life on Earth," said UNLV geochemist and principal investigator on the project Elisabeth Hausrath. "It is used in DNA, RNA, membranes, and more. It is reasonable to think that it may be needed for life elsewhere, if there is life elsewhere."
The research team found the synthetic Martian minerals much more soluble than those on Earth - meaning they have the potential to release more phosphate into water. Their measurements suggest that phosphate concentrations in wet environments on early Mars may have been more than twice those of early Earth.
"We didn't find evidence of life on Mars. That is still an unanswered question," said Hausrath. "Hopefully future missions to Mars can look for conditions of habitability. We discovered that since there is more available phosphate from the minerals on Mars, it probably means that there is less of a barrier to potential life on Mars."
According to Adcock, phosphate incorporated into Earth's earliest organisms must have come from minerals, but phosphate-containing minerals on the Earth's surface dissolve very slowly. The resulting limited availability of phosphate in aqueous environments is thought to have been a hurdle to the emergence of life on Earth.
"It is amazing that locked in every rock is a story," Adcock said. "Such as this case, when you consider that a particular mineral in a rock and how it behaves with water may have been a determining factor in the origin and persistence of life here - and possibly on Mars."
Ongoing and future work includes using the measured data in models of Mars, and studying clay minerals relevant to other indicators of possible habitability on Mars.
Grant funding for the research came from the NASA Mars Fundamental Research Program, the Nevada Space Grant Consortium, and the Geological Society of America. The research team included Christopher Adcock and Elisabeth Hausrath of the UNLV Department of Geoscience, and Paul Forster of the UNLV Department of Chemistry.
The study "Readily available phosphate from minerals in early aqueous environments on Mars" appeared in the September issue of the journal Nature Geoscience, and is discussed in a Nature Geoscience News and Views.