More than 20 amino acids—key ingredients for life—have been identified in samples collected from an asteroid, marking the first time that these important organic compounds have ever been found in an asteroid that is still in space, reports The Japan Times.
Amino acids are the building blocks of proteins, complex molecules that are essential to living creatures, which means that tracing back the origin of these compounds on Earth might unravel the mysteries of how life first emerged on Earth, and even if it exists elsewhere.
Scientists have previously detected amino acids in asteroid chunks that fell to Earth, but these meteorites are eroded by outer space forces, such as solar radiation and cosmic rays, and also damaged by their fiery descents through Earth’s atmosphere and impacts on the ground.
The discovery of roughly two dozen amino acids in rocks collected by Japan’s Hayabusa2 spacecraft from Ryugu, a nearby asteroid that is potentially hazardous to Earth, now confirms that these ancient space rocks are packed with important organic compounds. Crucially, the samples contain the first uncontaminated dirt studied from underneath an asteroid’s surface, which has not been weathered by the same forces as surface samples or meteorites that fall to Earth.
The spacecraft was able to obtain this subsurface material by shooting an impactor at the asteroid, and scooping up the debris dislodged by the collision. The finding adds to the evidence that asteroid impacts early in our planet’s history may have provided some of the materials that later gave rise to life.
"The Ryugu material is the most primitive material in the solar system we have ever studied," Hisayoshi Yurimoto, a geoscience professor at Hokkaido University who led the initial chemical analysis of the Hayabusa2 mission, said at a recent conference, according to Space.com.
Hayabusa2 delivered the samples, which total more than five grams, to Earth in December 2020. The spacecraft is the successor of Japan’s original Hayabusa probe, which became the first mission to return a sample from an asteroid to Earth in 2010.
Meanwhile, NASA’s OSIRIS-REx mission is expected to return a much larger batch of asteroid rock—some 60 grams, from the potentially hazardous object Bennu—in 2023. This ever-growing collection of rocks from the solar system’s asteroids, which date back to the beginning of the solar system, is bound to shed more light on Earth’s past, including the unsolved enigma of its first lifeforms.