5000 feet beneath the surface of the Earth’s largest and deepest Pacific ocean, lies extremely rare Plutonium-244, a trace of violent cosmic events that happened millions of years ago in deep interstellar space. The recently found isotope, an element with the same number of protons but a different mass of radioactive Plutonium, has a half-life of more than 80 million years. This discovery has made scientists rethink the cause of the existence of heavy metals such as gold, uranium, and others on Earth.
According to the scientists at the Australian Nuclear Science and Technology Organisation (ANSTO), a rare cataclysmic event happened about 4.5 billion years ago, before the formation of our solar system. Based on ANSTO’s ultrasensitive measurement of the plutonium isotope, the violent astronomical event could have been a merger of two neutron-stars which contributed to the existence of heavy metals beneath the earth’s crust.
Many of the heavy metals that sit after iron in the periodic table could not be created on ordinary Earth conditions, according to astrophysical theories. Only large-scale cosmic events, such as a supernova, nuclear fusion inside a star or other astronomical events could have produced them.
“However, it is not clear if supernovae are powerful enough to account for the range of elements that are around us,” said Micheal Hotchkis, the leading scientist at the Centre for Accelerator Science, ANSTO in a news release by the Australian research organisation. Hotchkis is one of the co-authors of a study that proposed the contribution of sources other than supernovae in the formation of the isotopes of iron and plutonium.
According to the research, r-processes or rapid neutron capture processes — the processes inside stars responsible for the formation of these metals –do happen in supernovae but they could not have produced enough to explain the amount of presence of heavy metals on the Earth. The study was published in the Science journal on May 14, 2021.