Mars: Photolysis produced organic compounds

https://science.ku.dk/english/press/news/2024/organic-material-from-mars-reveals-the-likely-origin-of-lifes-building-blocks/
Two samples from Mars together deliver the
"smoking gun" in a new study showing the
origin of Martian organic material. The
study presents solid evidence for a
prediction made over a decade ago by
University of Copenhagen researchers
that could be key to understanding how
organic molecules, the foundation of
life, were first formed here on Earth.
...
Most recently, the discovery of sedimentary
organic material with particular properties
has had many researchers scratching their
heads. The properties of these carbon-based
materials, in particular the ratio of its
carbon isotopes, surprised researchers.
Organic materials with such properties, if
found on Earth, would typically be a sign
of microorganisms, but they can also be the
result of non-biological, chemical processes.
The find obviously had researchers scrambling
for a clear answer, but nothing seemed to fit.
...
As co-author and chemistry professor Matthew
Johnson puts it, it is "the smoking gun"
needed to confirm a decade old theory of his
about so-called photolysis in Mars'
atmosphere.
With the Curiosity sample, the new research
is able to prove with reasonable certainty
that the Sun broke down CO2 in the Martian
atmosphere billions of years ago - as the old
theory predicted. And that the resulting
carbon monoxide gradually reacted with other
chemicals in the atmosphere synthesizing
complex molecules – and thus providing Mars
with organic materials.
“Such carbon-based complex molecules are the
prerequisite of life, the building blocks of
life one might say. So, this it is a bit like
the old debate about which came first, the
chicken or the egg. We show that the organic
material found on Mars has been formed through
atmospheric photochemical reactions - without
life that is. This is the 'egg', a
prerequisite of life. It still remains to be
shown whether or not this organic material
resulted in life on the Red Planet." said
Johnson...
...
The paper is public:
https://www.nature.com/articles/s41561-024-01443-z
Synthesis of 13C-depleted organic matter from
CO in a reducing early Martian atmosphere