Boron, believed to have played a key role in the formation of RNA and thus the development of life, was identified in a Martian meteorite by researchers from the University of Hawaii at Manoa NASA Astrobiology Institute.
Located by an Antarctic Search for Meteorites team during a 2009-2010 field season in Antarctica, the minerals the rock contains, as well as its chemical composition, clearly show a Martian origin, according to researchers.
Using the ion microprobe in the W. M. Keck Cosmochemistry Laboratry at the University of Hawaii, the team was able to analyze veins of Martian clay in the meteorite that, after ruling out contamination from Earth, they determined contained 10 times more boron than in any meteorite previously measured.
“Borates may have been important for the origin of life on Earth because they can stabilize ribose, a crucial component of RNA,” postdoctoral student James Stephenson said. “In early life RNA is thought to have been the informational precursor to DNA.”
In fact, RNA may have been the first molecule to store information and pass it on to the next generation - a crucial step in the story of evolution.
Furthermore, while life has since evolved a sophisticated mechanism to synthesize RNA, the first RNA molecules were obviously made without such help.
One of the most difficult steps in the construction of RNA nonbiologically is forming the RNA sugar component, ribose. However, while previous tests have shown that without borate, boron’s oxidized form, Earth’s chemicals fail to build ribose, the process occurs spontaneously in its presence.
“Given that boron has been implicated in the emergence of life, I had assumed that it was well characterized in meteorites,” Stephenson said.
While talking with a coworker over beers after work one day, Stephenson found this was not this case.
“I was shocked and excited,” he said regarding the discovery, and quickly learned that both the samples and the specialized machinery needed to analyze them were right there at the school he was already attending.
The resulting study suggests that when life was getting started on Earth, borate could also have been concentrated in deposits on Mars.
The significance, according to evolutionary biologist Lydia Hallis, the same coworker that gave Stephenson the idea of the study in the first place, goes beyond even Mars.
“Earth and Mars used to have much more in common than they do today,” she said. “Over time, Mars has lost a lot of its atmosphere and surface water, but ancient meteorites preserve delicate clays from wetter periods in Mars’ history.”
Since the Martian clay analyzed in the study is thought to be up to 700 million years old – far older than any clay left on Earth’s crust as a result of plate tectonics – Hallis further argues that the rock doesn’t just inform scientists about Mars, but early Earth as well.