New research backs up the old hypothesis that the key ingredients for life may have come to Earth on an asteroid billions of years ago. A modern case in point: The asteroid Bennu contains all the materials needed for life.
The OSIRIS-REx mission launched in 2016. Its main aim was to study Bennu and retrieve samples to bring back to Earth. The spacecraft reached Bennu in 2018 after traveling 320 million kilometers from Earth. It spent two years mapping its surface, then collected a 120g sample before landing back on Earth in 2023. Since then, scientists around the world have been unraveling its secrets.
The sample from Bennu. Photo: NASA/Erika Blumenfeld/Joseph Aebersold
Asteroids like Bennu are essentially time capsules, revealing the chemical makeup of the early solar system. Meteorites undergo significant changes when they enter the Earth’s atmosphere before crashing into its surface, but the material from Bennu is completely uncontaminated. Researchers have never seen anything like it before.
“There were things in the samples that completely blew us away,” said Sara Russell, co-author of the study. “The combination of the molecules and minerals preserved are unlike any extraterrestrial samples studied before.”
Bennu’s samples contain amino acids, minerals containing water, and complex carbon structures. The presence of hydrated minerals suggests that Bennu once even had liquid water. Scientists have identified 14 out of the 20 amino acids used by organisms on Earth to build proteins and the four nucleotide bases that we see in DNA.
OSIRIS-REx. Image: NASA
Far-reaching implications
“What we’re seeing in these samples is a unique combination of minerals and organic molecules that are unlike anything we’ve encountered in previous meteorites,” says Russell. “This suggests Bennu and similar asteroids played a crucial role in delivering materials that could have supported the origin of life.”
The discovery of life’s essential ingredients in Bennu’s material has far-reaching implications. It is likely that similar asteroids also delivered these building blocks of life to other planets and moons within our solar system. Mars, Europa, and Enceladus, in particular, have water and organic molecules.
“The early Solar System was really turbulent, and there were millions of asteroids like Bennu flying about,” said co-author Ashley King.
