Three nuclear science discoveries from ANU you should know about

For many mortals, thoughts about the origins of the universe and how we, and all planets, came to be is too much for our brains to handle. Fortunately, nuclear scientists at ANU are turning their minds to the challenge. 

The Heavy Ion Accelerator Facility (HIAF) and Research School of Physics at ANU are helping researchers tackle some of the universe’s biggest mysteries. From discovering alien elements at the bottom of the ocean to learning more about the origin and abundance of the chemical elements that make up all life, ANU researchers are pushing scientific boundaries as they reach for the stars.  

Scouring the seabed, scientists discover something out of this world 

Taking their research to new depths, ANU scientists have found evidence of alien elements, including ancient stardust, from interstellar space entombed in sediment at the bottom of the ocean. These radioactive isotopes, known as iron-60, a special form of iron, and plutonium-244, a variant of plutonium, crash landed on Earth at some point during the past 10 million years.  

While scientists already know the origins of iron-60 — it is formed in massive stars and ejected when stars die bright, explosive deaths, an event known as a supernova — there is lots we don’t know about plutonium-244. Deciphering the origins of plutonium-244 could bring us a step closer to learning how all life became possible.  

“Understanding where in the universe plutonium-244 came from, and how it was created, helps us learn more about how the universe became the way we see it today and how all life became possible,” ANU PhD researcher Dominik Koll says. 

“Earth is indeed connected to and affected by the worlds outside of the solar system. And stardust found on our planet is just like a message in a bottle sent from far, far away.” 

Carbon-creating stars hold keys to the secrets of the universe   

A new measurement of how quickly stars create carbon may trigger a major shift in our understanding of how stars burn and eventually die, as well as shed new light on the origin and abundance of chemical elements—the ‘building blocks’ of life. 

Nuclear physicists from ANU and the University of Oslo have replicated how stars make carbon. The researchers found that carbon — the foundation of all life — is produced in massive stars 34 per cent faster than previously thought.  
 
The carbon and other elements formed inside stars eventually become the dust and gas from which planets are formed. The production of carbon also serves as the pathway for the formation of heavier elements such as oxygen, magnesium, silicon, calcium and iron.

On Earth, carbon chemistry is the basis for all life. Emeritus Professor Tibor Kibedi from ANU says this new measurement could help scientists decipher many puzzles of the universe. 

“It would affect our understanding of how stars change over time, how they produce elements heavier than carbon, and how we measure the age of stars and how long they will live for,” Kibedi says. 

“The carbon production rate also tells us how often we can expect to see supernova explosions, and even whether those explosions leave behind neutron stars or black holes.” 

Ushering in a new geological age in Earth’s timeline 

Harnessing the power of the HIAF, nuclear scientists at ANU have detected the radioactive chemical element, plutonium, entombed in sediment samples from Beppu Bay in Japan. It’s a fossilised record of the nuclear weapons testing in the 1950s and 1960s.    

The ANU team confirmed the plutonium originated in the Marshall Islands, which, for several years was used by the United States as an atomic bomb testing site. 

Human impact on Earth’s climate and ecosystems has reached the level at which many believe the planet has now entered a new geological age, dubbed the Anthropocene period.  

ANU scientists found the plutonium in sediment in Beppu Bay provided a “clear and strong” signature. Their research provides major evidence that the plutonium immortalised in Beppu Bay is a leading candidate to officially mark the exact moment in history when the Anthropocene period began, and the point when humans began to adversely impact Earth.

“Using the state-of-the-art facilities at ANU we obtained measurements that not only indicated the source of the plutonium, but also the precise timing of when that plutonium appears in the geologic record,” Associate Professor Stephen Tims says.

“Our technique has the potential for significant use in helping to date and investigate environmental, historical, geological and biological processes, and for improving Earth’s climate and oceans models.” 

From studying life beyond the stars to unravelling the mystery of how life on Earth became possible, a day in the life of a nuclear scientist is anything but ordinary. If this sounds like the career for you, check out the Bachelor of Science and Master of Science in Nuclear Science degrees on offer at ANU.  

You can learn about other fascinating nuclear science discoveries from ANU at the Research School of Physics website.