Organic Molecules Abound in Space, Suggesting Life’s Extraterrestrial Origins

The universe is teeming with complex carbon-based compounds, known as organic molecules, which are fundamental to life as we know it. Recent explorations of comets and asteroids have revealed that these organic molecules are widespread throughout space, hinting that the building blocks of life may have originated in the depths of the cosmos.

The journey of discovery began in 1986 when the European Giotto spacecraft conducted the first in-situ analysis of a comet, Halley, detecting an unexpected abundance of organic species in its coma. This was followed by the Rosetta spacecraft’s mission to comet 67P/Churyumov-Gerasimenko, where, in 2015, it detected simple organic compounds, including glycine—a building block of proteins—marking the first direct detection of this molecule on a comet. By 2022, researchers analyzing Rosetta’s data identified 44 organic compounds, some with molecular weights up to 140 Daltons.

Asteroids have also provided valuable insights. Japan’s Hayabusa2 and NASA’s OSIRIS-REx missions collected samples from asteroids Ryugu and Bennu, respectively, and returned them to Earth. Analyses revealed a diverse array of organic compounds. Scientists studying Ryugu found at least 20,000 varieties of carbon-based compounds, including 15 different amino acids, suggesting a rich prebiotic chemistry from which life could emerge.

These findings raise intriguing questions about the origins of organic molecules. Did they form in the cold, dark clouds of interstellar space, or in the energetic environments near young stars? Understanding how planets, including early Earth, acquired these organics in the absence of life is crucial for unraveling the mysteries of our own origins.

Astronomical observations have traced certain large carbon structures, such as polycyclic aromatic hydrocarbons (PAHs), back to about 1.5 billion years after the Big Bang. These sturdy rings and chains of carbon atoms often form in the outflows of dying stars, in processes not too dissimilar from combustion on Earth. Interstellar space is now known to harbor over 200 carbon-containing compounds, highlighting the cosmic abundance of life’s building blocks.

These discoveries suggest that the organic molecules essential for life are not unique to Earth but are widespread throughout the universe, potentially seeding life across the cosmos.

Reference: Organic molecules on asteroids hint at life beginning in deep space