Recreating a piece of the universe in a bottle might sound like science fiction, but it’s exactly what Linda Losurdo did.
Losurdo, a doctoral student in materials and plasma physics at the University of Sydney, used simple gases and electricity to recreate conditions usually found in the vicinity of stars and supernovas to produce a tiny amount of cosmic dust.
Cosmic dust is an essential component of the universe; it plays a role in star formation and acts as a catalyst for organic molecules that constitute the building blocks of life. The dust is abundant in interstellar space — the vast region between stars, and it is embedded in comets and asteroids. However, it’s difficult to study on Earth because, although particles and rocks from space constantly bombard our planet, most of that material burns up in the atmosphere. What little survives in the form of meteorites is often impossible to locate and collect.
Losurdo said that by making cosmic dust in the lab, she hopes to give scientists an extra tool to understand how life started on Earth.
“When we’re looking at big questions like the origins of life, we have to look at where the building blocks started from,” she said. “Where did all the carbon on Earth begin its life, and what type of journey did it have to go through in order to then be able to build into things like amino acids?”
Amino acids were among the earliest molecules to appear on Earth and are connected to most life processes, including the formation of proteins. But there’s a big question, Losurdo said, about whether amino acids were formed on Earth or if they had a different origin: space.
Producing a cosmic dust analogue can help researchers investigate this and other questions about the crucial chemistry that led to life on Earth, without having to rely exclusively on samples from space.
“Meteorites take so long to fall, and it’s quite hard to collect dust, let alone collect dust near a giant, dying old star,” added Losurdo, whose work was published last week in The Astrophysical Journal of the American Astronomical Society. “So we must have something to study. And even if it’s only a little bit, we get a lot more information out of it.”
The cosmic dust in a lab consists of a mix of gases that glow different colors when excited by electricity. - Linda Losurdo/University of Sydney
Building up a database
To make the cosmic dust, Losurdo started with nitrogen, carbon dioxide and acetylene — a colorless, odorless gas made up of carbon and hydrogen. With coauthor David McKenzie, a professor of materials physics at the University of Sydney, she vacuumed the air out of a glass tube and introduced the gases. The pair then applied 10,000 volts of electricity to the gases for an hour, making a type of plasma, or electrically charged gas, called a “glow discharge.”
“You’re completing a circuit across the gas itself, so the gas is getting excited, electrons are flying off, creating an environment in which things want to bind and coalesce and aggregate,” Losurdo said. “And that’s a very natural process. It’s something that we know for certain happens around stars.”
The result was a few milligrams of “dusty nanoparticles,” she added. “They are a little bit challenging to collect and analyze, so what I do is actually get the dust to deposit itself on a silicon wafer,” she said. “Silicon is a fantastic material for so many reasons, and it allows us to only see the stuff on the wafer itself and not the silicon.”
In total, Losurdo produced about a gram of cosmic dust, which was deposited on a silicon wafer for analysis. - Fiona Wolf/University of Sydney
The ultimate goal of this process was to recreate space-like conditions. “We can never truly do things to the full complexity that nature does — nature will always be better than us,” Losurdo said. “But what we’re trying to do is get in that plausible range of conditions where our setting would represent, we hope, the envelope of a giant star, or a supernova remnant, or a new nebula.”
The artificial dust created this way is similar to cosmic dust in a pristine state right after it’s made. Once it becomes a catalyst for organic molecules, or becomes embedded in comets and meteorites and eventually reaches Earth, the dust has undergone multiple chemical processes, so having a lab-made analogue of its original state can help scientists understand its evolution, according to Losurdo.
The next step, the researchers said, is to try changing the conditions under which the cosmic dust is made, to build up a database of different types. “We hope that one day our dust is going to be even closer to the real thing,” Losurdo said, “and can be ‘matched’ to specific objects like meteorites.”
Cosmic dust made in a lab is pictured as it appears under a microscope. - Vijay Bhatia/Linda Losurdo/University of Sydney
A clever technique
Exploring the formation and nature of cosmic dust is a crucial part of the story of the origin of life, said Martin McCoustra, a professor of chemical physics at Scotland’s Heriot-Watt University, who was not involved with the study.
“Chemical complexity evolved from a very simple starting chemistry of hydrogen atoms, carbon monoxide, water and a few other small molecules deposited on dust grains,” McCoustra said in an email. “This evolution can be replicated in laboratories,” he added, calling the study convincing.
The researchers used a clever technique to recreate the possible formation histories of cosmic organic material, according to Tobin Munsat, a professor of physics at the University of Colorado Boulder.
“Ultimately, this is what lab work is all about — recreating an analogue under controlled conditions that we can then apply to understand the natural world,” Munsat, who did not participate in the research, wrote in an email.
The results corroborate the idea that raw materials, which eventually contribute to life, are shaped by the energetic environments in which they form, Munsat said. This fact can potentially allow scientists to reconstruct the history of organic compounds found in asteroids, comets and interstellar dust, rather than treating them merely as chemically uniform.
The study bridges an important gap between telescopic observations and laboratory analysis, said Damanveer Grewal, an assistant professor in the department of Earth and planetary sciences at Yale University, who also did not take part in the study.
The experiment provides a good starting point to test current models of how organic matter evolves in space, Grewal added in an email.
“The findings suggest that complex organic matter forms readily in stellar environments and is not unique to our solar system,” he said. “If these materials are widespread, it implies that the essential chemical building blocks for life are likely available to planetary systems throughout the galaxy.”
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