In a recent study, scientists have taken to baking meteorites to release and analyse gases to have a better understanding of early atmosphere of other rocky planets out there in space. The study has revealed that the initial atmospheres of terrestrial planets may have been significantly different from many of the common assumptions used in theoretical models. Researchers at the University of California (UC), Santa Cruz, US, heated meteorite samples that landed at different times in different parts of the Earth in a high-temperature furnace and analysed the gases they released to investigate the atmospheres.
Maggie Thompson, the first author of the study, said the information will come in handy when we start “being able to observe exoplanet atmospheres with new telescopes and advanced instrumentation.”
Myriam Telus, the co-author of the study and assistant professor of Earth and planetary sciences at UC Santa Cruz, said that when the building blocks of a planet are coming together, the material is heated and gases are produced. “And if the planet is large enough, the gases will be retained as its atmosphere,” added Telus.
Three meteorites of CM-type carbonaceous chondrites — Murchison, Jbilet Winselwan, and Aguas Zarcas — were analysed. The materials that made up these meteorites were closest in terms of the materials that formed the Sun and planets. Thompson said these meteorites were left over materials from the building blocks that went into forming the planets in the solar system.
While the Murchison chondrite fell in Australia in 1969, Jbilet Winselwan was collected in Western Sahara in 2013, and Aguas Zarcas fell in Costa Rica in 2019. Researchers from three departments at UCSC — Astronomy and Astrophysics, Earth and Planetary Sciences, and Physics — analysed these meteorites.
How did the researchers analyse the meteorites?
The researchers, while working with material scientists in the physics department, set up a furnace that was connected to a mass spectrometer and a vacuum system. When the meteorite samples were heated to 1,200 degrees Celsius, the system examined the volatile gases the minerals produced in the sample. Water vapour was the dominant gas, with significant amounts of carbon monoxide and carbon dioxide, and smaller amounts of hydrogen and hydrogen sulfide gases also released, according to the statement.
Telus said models of planetary atmospheres often assume solar abundances — “a composition similar to the sun and therefore dominated by hydrogen and helium.”
However, she added, on the basis of outgassing from meteorites, one would expect water vapour to be the dominant gas, followed by carbon monoxide and carbon dioxide. “Using solar abundances is fine for large, Jupiter-size planets that acquire their atmospheres from the solar nebula, but smaller planets are thought to get their atmospheres more from outgassing,” Telus said.
Other researchers, too, in the past have carried out heating experiments but for other purposes using different methods. “A lot of people are interested in what happens when meteorites enter Earth’s atmosphere, so those kinds of studies were not done with this framework in mind to understand outgassing,” Thompson said.
“It may seem arbitrary to use meteorites from our solar system to understand exoplanets around other stars, but studies of other stars are finding that this type of material is actually pretty common around other stars,” Telus noted.
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