Asteroid rocks begin to reveal the origins of our solar system

Researchers from Curtin University are part of a global team of scientists investigating how our solar system formed. They do this by uncovering the secrets hidden within a 4.5 billion year old asteroid.

In September last year, NASA’s multibillion-dollar OSIRIS-REx mission successfully returned samples from the asteroid Bennu after a seven-year journey, sending specimens to research labs around the world, including Curtin.

A new study published in Meteoritics and planetary science reveals the first findings of the samples – and there were some surprises for the team.

The samples consisted mainly of dark particles, ranging in size from dust to about 3.5 cm in length. However, there were also some lighter particles scattered throughout, and some of the rocks also contained brighter material that formed veins and crusts.

OSIRIS-REx Sample Analysis Team member Associate Professor Nick Timms from Curtin’s School of Earth and Planetary Sciences said that, unlike meteorites that have fallen to Earth, the material collected from Bennu has been kept in pristine condition and has not been contaminated by the atmosphere or biosphere of the Earth.

“Analyses show that Bennu is among the most chemically primitive materials known, with a composition similar to that of the visible surface of the Sun,” said Associate Professor Timms.

“This indicates that Bennu has undergone different processes than the planets, and that these processes have changed the abundance of certain elements relative to the Sun.”

Analysis of the samples confirmed the presence of several components previously thought to be present, such as hydrated phyllosilicates (a type of mineral that forms in the presence of water) and carbon-rich material.

“This means that asteroids like this may have played an important role in delivering water and the building blocks of life to Earth,” said Associate Professor Timms.

The samples also contained several unexpected components.

“We were surprised to find magnesium-sodium phosphates, further suggesting that Bennu experienced chemical environments that may have involved water,” said Associate Professor Timms.

“We also found other trace elements that provide clues to the processes that have occurred on Bennu over the past billions of years, such as temperature and pressure conditions.

“These trace elements help paint a picture of Bennu’s evolution and also provide insight into the early Solar System and how the various planetary bodies in the Solar System formed.”

Associate Professor Timms said there are many more discoveries to be made from the Bennu samples, which will have a wide range of implications for understanding the early solar system.

“The sample contains presolar grains created before our solar system existed, which could provide a detailed biography of the lives of ancient stars,” said Associate Professor Timms.

“Understanding the composition of asteroids also has very practical implications, from identifying potential mining opportunities to knowing how best to protect ourselves if an asteroid is on a collision course with Earth.”