Washington: A new study has provided strong evidence that organic carbon did, indeed, originate on Mars, although it is not of biological origin.
Molecules containing carbon and hydrogen -- the building blocks of all life on Earth -- have been the targets of missions to Mars from Viking to the present day.
While these molecules have previously been noticed in meteorites from Mars, scientists have disagreed about how this organic carbon was formed and whether or not it came from Mars.
Theories about their origin include contamination from Earth or other meteorites, the results of chemical reactions on Mars, or that they are the remnants of ancient Martian biological life.
The new findings give researchers insight into the chemical processes taking place on Mars and will help aid future quests for evidence of ancient or modern Martian life.
Carnegie’s Andrew Steele and a consortium of scientists that includes Planetary Science Institute’s Marc Fries examined samples from 11 Martian meteorites whose ages span about 4.2 billion years of Martian history.
They detected large carbon compounds in 10 of them. The molecules were found inside of grains of crystallized minerals. Since these molecules were found in Martian meteorites of such an extraordinary span of ages, their presence means that Mars has been making its own organic compounds throughout its history and apparently continues to do so today.
“We knew these organic compounds were in the Martian meteorites, but until we performed this study no one knew exactly where they were in the rocks or how they were formed,” said Fries, a research scientist at the Planetary Science Institute.
“It was a puzzle, and now we finally have enough pieces in place to say, okay, now we understand what is going on here,” he added.
Using an array of sophisticated research techniques, the team was able to show that at least some of the macromolecules of carbon were indigenous to the meteorites themselves and not contamination from Earth.
“What this all means is that Mars is making its own organic compounds. Previous to this, we thought that carbon compounds on Mars only fell there in meteorites, or perhaps were bound up in any life forms that might be living there. Now we know that simply finding organic compounds that aren’t from meteorites doesn’t automatically mean that they come from life,” Fries said.
“While it sounds like it complicates things, it actually gives us a clearer picture of Mars and will help us build robust conclusions about whether anything is, or has been, alive there,” he asserted.
The results were published May 24 in Science Express.