Analytical improvements and assessment of long-term performance of the oxidation-denitrifier method.

Unlabelled: The analysis of the nitrogen (N) isotopic composition of organic matter bound to fossil biomineral structures (BB-δ N) using the oxidation-denitrifier (O-D) method provides a novel tool to study past changes in N cycling processes.

Methods: We report a set of methodological improvements to the O-D method, including (a) a method for sealing the reaction vials in which the oxidation of organic N to NO takes place, (b) a recipe for bypassing the pH adjustment step before the bacterial conversion of NO to N O, and (c) a method for storing recrystallized dipotassium peroxodisulfate (K S O ) under Ar atmosphere.

Results: The new sealing method eliminates the occasional contamination and vial breakage that occurred previously while increasing sample throughput.

Xenon isotopes in 67P/Churyumov-Gerasimenko show that comets contributed to Earth's atmosphere.

The origin of cometary matter and the potential contribution of comets to inner-planet atmospheres are long-standing problems. During a series of dedicated low-altitude orbits, the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) on the Rosetta spacecraft analyzed the isotopes of xenon in the coma of comet 67P/Churyumov-Gerasimenko. The xenon isotopic composition shows deficits in heavy xenon isotopes and matches that of a primordial atmospheric component.

DO and HDS in the coma of 67P/Churyumov-Gerasimenko.

The European Rosetta mission has been following comet 67P/Churyumov-Gerasimenko for 2 years, studying the nucleus and coma in great detail. For most of these 2 years the Rosetta Orbiter Sensor for Ion and Neutral Analysis (ROSINA) has analysed the volatile part of the coma. With its high mass resolution and sensitivity it was able to not only detect deuterated water HDO, but also doubly deuterated water, DO and deuterated hydrogen sulfide HDS.

Prebiotic chemicals-amino acid and phosphorus-in the coma of comet 67P/Churyumov-Gerasimenko.

The importance of comets for the origin of life on Earth has been advocated for many decades. Amino acids are key ingredients in chemistry, leading to life as we know it. Many primitive meteorites contain amino acids, and it is generally believed that these are formed by aqueous alterations.

Photochemistry of forbidden oxygen lines in the inner coma of 67P/Churyumov-Gerasimenko.

Observations of the green and red-doublet emission lines have previously been realized for several comets. We present here a chemistry-emission coupled model to study the production and loss mechanisms of the O(S) and O(D) states, which are responsible for the emission lines of interest for comet 67P/Churyumov-Gerasimenko. The recent discovery of O in significant abundance relative to water 3.