Life from a meteorite?
According to a report published earlier this week in PLOS One, researchers have found materials implicated with the emergence of life in a Martian meteorite. Born from a unique interdisciplinary environment, the paper ties together the workings of evolutionary biology and cosmo-chemistry, specialties of lead authors James Stephenson and Lydia Hallis.
The research took place at the University of Hawaii’s NASA Astrobiology Institute (UHNAI), with the discovery of high concentrations of boron in the meteorite. In its oxidized form (borate), it’s believed that boron played a critical role in the formation of RNA, a key building block for life. Despite this well documented relationship, boron remains largely unstudied in meteorites.
For the origin of life on Earth, borates were critical in their role of stabilizing ribose, a crucial component of RNA. RNA, of course, is thought to have been the informational precursor to DNA. In light of evolution, RNA may have been the first molecule to store information and pass it on to the next generation.
Life has now evolved sophisticated mechanisms to synthesize RNA, but the first RNA molecules would have unlikely received any such help. The most difficult step encountered in any attempt to make RNA non-biologically is the formation of the RNA sugar component, ribose. Previous studies have shown that, without borate, the chemicals available on early Earth fail in their attempts to build ribose. In the presence of borate, ribose is found to spontaneously produce and stabilize.
During the 2009 – 2010 field season, the Antarctic Search for Meteorites team found the meteorite in question in Antarctica. Given the minerals present and the chemical composition, the meteorite was clearly of Martian origin.
Making use of an ion microprobe, the research team was able to analyze veins of Martian clay in the meteorite. Ruling out contamination from Earth, it was determined that the boron abundances in these clays were ten times higher than in any previously measured meteorite.
On Earth, borate-enriched sediments and clay deposits are relatively common, but such deposits have never previously been found on any extraterrestrial body. The presence of these borate-enriched clays on Mars implies that such clays may also have been present on early Earth.
This significance goes beyond an interest in Mars alone. Earth and Mars used to share more similarities than they do today. Thus, Martian clays may be able to provide essential information on environmental conditions of early Earth.