Substances that are an important part of the origin of life on Earth, including the simple amino acid glycine and the element phosphorus - which are components of DNA and the cell wall were discovered in the halo of comet P/67 Churyumov-Gerasimenko
Rosetta's comet in August 2015, when it was closest to the Sun, when most of the glycine was detected. Photo: European Space Agency
Substances that are an important part of the origin of life on Earth, including the simple amino acid glycine and the element phosphorus - which are components of DNA and the cell wall were discovered in the comet
P/67 Churyumov-Gerasimenko.
The possibility that water molecules and organic substances were brought in the early years of the Earth through the impact of asteroids and comets has long been the subject of an important debate in science.
Although the Rosina device on board the Rosetta spacecraft discovered a significant difference in the composition between the ice of the comet P/67 and the composition of the oceans on Earth, the same device has now demonstrated that even if comets did not play a large role in the water supply as previously thought, they certainly had the potential to provide
the components of life.
While more than 140 different molecules have already been identified in the interstellar material in the many space missions to date, no amino acids have been found. Clues to the existence of the amino acid glycine were found in NASA's Stardust mission that passed by comet Wild 2 in 2004, but the possibility of terrestrial contamination of dust samples collected and brought to Earth could not be ruled out. Now for the first time, Rosetta has now confirmed the existence of this protein in the thin atmosphere - the halo of the comet.
The first discovery of glycine on Rosetta was already in October 2014, shortly after the spacecraft's approach to the comet and shortly before the landing of the Philae lander. Most of the measurements were made during the comet's perilion - the closest point to the Sun along the comet's orbit in August 2015, when the gas emission from the comet was at its peak.
"This is the first unequivocal detection of glycine in the thin atmosphere of a comet," says Catherine Altweg of the University of Bern in Switzerland, principal investigator of the Rosina instrument and of the current study. The findings were published in the journal SCIENE.
Glycine is difficult to detect due to its non-reactive nature. It takes off (turns from solid directly into gas) at a temperature of 150 degrees Celsius and this means that at the temperature prevailing on the surface of the comet very little of it appears in gaseous form.
"We see a correlation between the glycine and the dust, which raises the possibility that the material was ejected from the ice cores on the comet's mantle immediately after they were heated in the halo, possibly together with other volatile materials," Altweg said. At the same time, the researchers also discovered the organic molecules methylamine and ethylamine essential for the formation of glycine. Unlike the other amino acids, glycine is the only one that has shown the ability to form without the presence of liquid water. "The presence of these two substances and the correlation between the dust and the glycine also hint to us how the glycine was formed," Altweg said.
Phosphorus, a key element for life on earth
Another exciting discovery made for the first time by Rosina is the element phosphorus, which is a key component in all living things, and is found in the structural framework of DNA and RNA.
"Many organic molecules have already been identified by Rosina, meanwhile another exciting confirmation of basic ingredients for life such as glycine and phosphorus has been added to them. These discoveries confirm our idea that comets have the potential to provide key molecules in prebiotic chemistry (pre-life)" says Matt Taylor, scientist at the European Space Agency's Rosetta project. "The proof that comets are reservoirs of the most primitive material in the solar system, and are a vehicle that could have transported these essential elements to Earth, is the fulfillment of one of the main goals of the Rosetta mission, and we are happy with this result."
to the notice of the researchers
More of the topic in Hayadan:
- Paolo Perry, director of ESOC of the European Space Agency in an interview with the science website: "Rosetta is not a typical space mission"
- The news from Rosetta - the rate of water evaporation is increasing
- Rosetta discovered liquid nitrogen on the comet
- Rosetta photographed a valley formed on the comet as a result of material escaping into space
