Researchers discover solid phosphorus from a comet

An international study conducted by the University of Turku, Finland, found phosphorus and fluorine in solid dust particles collected from a comet. The discovery indicates that all the most important elements necessary for life may have been delivered to Earth by comets.

Researchers discovered phosphorus and fluorine in solid dust particles collected from the inner coma of comet 67P / Churyumov – Gerasimenko. The comet takes 6.5 years to orbit the sun.

The dust particles were collected with the COmetary (COSIMA) secondary ion mass analyzer. The instrument was aboard the European Space Agency’s Rosetta spacecraft which tracked the comet a few kilometers away between September 2014 and September 2016. The COSIMA instrument collected dust particles directly in the comet’s vicinity. Three 1 cm plates and two targets were photographed from a distance. Particles were selected from these images and finally measured with a mass spectrometer. All the passages were controlled from the Earth.

The detection of phosphorus (P.⁺) ions in solid particles is contained in minerals or metal phosphorus.

“We have shown that apatite minerals are not the source of phosphorus, which implies that the discovered phosphorus comes in a smaller and possibly more soluble form,” says project leader Harry Lehto of the Physics and Astronomy Department of University of Turku.

This is the first time that the CHNOPS elements necessary for life are found in solid comet matter. Carbon, hydrogen, nitrogen, oxygen and sulfur have been reported in previous studies by the COSIMA team from, for example, organic molecules. The discovered phosphorus, or P, is the last of the CHNOPS elements. The discovery of P points to comet delivery as a potential source of these elements for the young Earth.

Fluorine was also detected with CF⁺ secondary ions originating from comet dust. The first discovery of CF gas was from interstellar dust in 2019. CF⁺ it is an ion now discovered on the comet and its characteristics in the cometary environment are still unknown.

The study was conducted by the Department of Physics and Astronomy of the University of Turku, Finland.

The article was published in Royal Astronomical Society Monthly Notices.