South Africa’s Makhonjwa Mountains are home to some of the oldest rocks on the planet – but not everything in this magnificent landscape originated on Earth. Scientists say they’ve discovered trace evidence of extraterrestrial organic matter buried within volcanic sediment from over 3.3 billion years ago.
“This is the very first time that we have found actual evidence for extraterrestrial carbon in terrestrial rocks,” astrobiologist Frances Westall from the CNRS Centre for Molecular Biophysics in France explained to New Scientist.
For billions of years, Earth has been rained upon by meteorites violently impacting and rearranging the planet’s surface. What do these space rocks leave behind when they get here?
It could be a lot.
Many scientists think some of the building blocks for life on our planet may have arrived as space-faring molecules; the new discovery in South Africa adds further weight to this tantalising possibility.
In a volcanic deposit called the Josefsdal Chert – which is part of the Makhonjwa Mountains region (aka the Barberton Greenstone Belt) – Westall and her team uncovered a 2 mm-thick rock layer characterised by two “anomalous” signals.
Using electron paramagnetic resonance (EPR) spectroscopy, the researchers found that the 3.3 billion-year-old rock contained two types of insoluble organic matter, both of which suggest extraterrestrial origins (the oldest extraterrestrial organic matter ever identified no less).
One of the EPR signals resembles something scientists have seen before in carbonaceous chondrites: ancient meteorite samples containing organic compounds.