As the Rosetta spacecraft remains in orbit around the comet 67P/Churyumov-Gerasimenko, the comet is slowly drifting toward its closest approach to the Sun, known as perihelion. As the comet moves closer to the Sun, intense sunlight liberates gases and dust in streams of material that form clearly visible streaks. The orbiter is able to sample some of the material liberated from the comet, and for the first time it has seen the tell-tale signature of Molecular Nitrogen.
Nitrogen is abundant on Earth as a gas, constituting the majority of our atmosphere. It is also present in the atmospheres of Pluto and Neptune’s largest moon Triton. Understanding where molecules like Nitrogen come from are a key to understanding the formation of the solar system and the origins of life on Earth.
However, even with this first-time discovery of Nitrogen originating on a comet, its very likely that the large amounts of nitrogen on Earth was not brought here by early comet bombardment. “The amount of molecular nitrogen brought to Earth by comets such 67P/Churyumov-Gerasimenko is small compared to other nitrogen-bearing molecules like ammonia,” says ROSINA Principal Investigator Kathrin Altwegg.
This adds to the growing body of evidence that comets forming in the same region as 67P did not bring water or other volatiles such as Nitrogen to early Earth. As the comet moves closer to the Sun through the next five months, the study of it’s gases and how it changes will give astronomers a deeper understanding of what elements it contains and has been releasing for millions of years.