Astronomers examining the composition of the Saturn moon Titan, has concluded that its rare atmosphere most likely are residues from cometary impacts

Saturn’s moon Titan has attracted much attention because of its massive nitrogen atmosphere, but the origin of this atmosphere is largely unknown. Massive secondary atmospheres on planets and satellites usually form only after a substantial differentiation of the body’s interior and chemical reactions during accretion, yet Titan’s interior has been found to be incompletely differentiated.

This has led the scientist to investigate and model Titan’s nitrogen atmosphere based on the assumption that it formed during the period of late heavy bombardment about four billion years ago, just as Earths wter is suspected to be

Their experiments show that ammonia ice converts to N₂ very efficiently during impacts. Numerical calculations based on our experimental results indicate that Titan would acquire sufficient N₂ to sustain the current atmosphere and that most of the atmosphere present before the late heavy bombardment would have been replaced by impact-induced N₂.

The scenario is capable of generating a N₂-rich atmosphere with little primordial Ar on undifferentiated Titan. If this mechanism generated Titan’s atmosphere, its N₂ was derived from a source in the solar nebula different from that for Earth, and the origins of N₂ on Titan and Triton may be fundamentally different from the origin of N₂ on Pluto.

Source: Natyre Geoscience