TAKE a deep breath. Can you taste the flavour of ancient space? Nitrogen in Earth鈥檚 atmosphere has been traced back to the spinning disc of dust and gas that formed our solar system, and may even have yielded ammonia to fuel organic reactions. This all comes courtesy of a meteorite found in Antarctica named after a popular brand of beer.
鈥淥ur [meteorite] samples were collected in Antarctica in the late 1970s,鈥� says of Friedrich-Schiller University in Jena, Germany. 鈥淭hey fell there hundreds or thousands of years ago.鈥� Known as chondritic meteorites, their history goes back some 4.6 billion years. At that time, our solar system was a vast disc of dust and gas, called the protoplanetary disc, spinning around the sun.
Harries and his colleagues were studying the make-up of the meteorites when they found a mineral called carlsbergite, named after the Carlsberg Foundation, an offshoot of the Danish brewery, which funded previous work on it.
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Carlsbergite is a rare composite of chromium and nitrogen. Looking at the ratio of stable and unstable isotopes in the nitrogen, Harries found that it was very close to the ratio in the nitrogen that makes up three-quarters of Earth鈥檚 atmosphere today. That suggests they have a common origin, and the nitrogen in our atmosphere came from the protoplanetary disc.
Harries also looked at the shape of the carlsbergite crystals, and found that they must have been formed under very high temperatures, in the presence of ammonia gas ().
Knowing the molecular composition of a given element at the time Earth was formed matters, says of the University of Paris-South, France. Nitrogen, for instance, can come as pure nitrogen gas or as ammonia, which also contains hydrogen. 鈥淭his makes a hell of a difference, particularly if you are interested in prebiotic molecules like amino acids,鈥� he says.
聯This makes a hell of a difference, particularly if you are interested in prebiotic molecules聰
Pure nitrogen is stable and unreactive, so an unlikely source for organic molecules, but ammonia can easily react to help form the organic chemistry that underpins life. So discovering that it was present even before our planet was formed may tell us something about the origins of life 鈥� although whether it helped trigger the formation of prebiotic molecules is still complete speculation.
鈥淭he presence of ammonia could have acted as an active ingredient in some of the chemistry needed to eventually get to life,鈥� says Hope Ishii of the University of Hawaii at Manoa. 鈥淏ut it鈥檚 still a long way between having ammonia and having life.鈥�
What about nitrogen compounds elsewhere in our solar system? 鈥淚t seems possible that ammonia and organic molecules were brought to other bodies like Mars and Europa,鈥� Harries says.
This article appeared in print under the headline 鈥淢eteorite named after beer acts as time capsule鈥�
