Comet 67P is hiding nitrogen that could solve a solar system mystery

[Judi Lynn]

SPACE 12 March 2020
By Leah Crane



Comet 67P has a hidden source of nitrogen
ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA


The mystery of the missing nitrogen in comets may finally be solved. These space rocks appear to have 10 times less nitrogen than they ought to based on our understanding of how they form, but a new finding from comet 67P/Churyumov-Gerasimenko might reveal how comets have been hiding their nitrogen.

The European Space Agency’s Rosetta spacecraft orbited 67P between 2014 and 2016, taking pictures of the comet and measuring its environment. Analysis of the light bouncing off the comet revealed that some compound was absorbing light from its surface, but researchers couldn’t immediately identify what it was.

Olivier Poch at the University of Grenoble in France and his colleagues compared the properties of that light with light bounced off artificial asteroid dust in the lab. This contained dust grains similar to those known to exist on 67P, as well as various other compounds. They found an astonishingly good match with ammonium salts, which contain nitrogen and hydrogen.

They also discovered similarities between the ammonium measurements and observations from asteroids, which means these rocks could have some of the chemical on their surfaces as well. This could help explain where the missing nitrogen is.

More:
https://www.newscientist.com/article/2237212-comet-67p-is-hiding-nitrogen-that-could-solve-a-solar-system-mystery/#ixzz6GbSQgPOM

[eppur_se_muova]

1. They give the spectrum of ammonium formate. Ammonium carbamate would seem a more obvious ...

candidate. It is formed whenever CO2 and NH3 meet.

https://en.wikipedia.org/wiki/Ammonium_carbamate

[Igel]

2. Better link.

https://science.sciencemag.org/content/367/6483/eaaw7462

Apparently the conclusion that it's ammonium formate (among the options) is driven by the absorption wavelength. My spectroscopy is sooo far in the past that I have nothing useful to say about the absorption lines for carbamate vs formate. (Or formate versus anything ... Spectroscopy in organic and instrumental chem classes, 1979-80. Now, 2020. Knowledge retention --> 0.)

I have to wonder if the same mechanisms that produce tholins can also account for formic acid production and nobody bothered to look specifically for carbamate or formate in the tangle of spectral lines.