HOUSTON, TX — Space rock samples gathered from the ancient asteroid Bennu contain the necessary ingredients for life: amino acids, DNA bases, and compounds containing nitrogen, according to an analysis released Tuesday. Those research findings were presented in the peer-reviewed journal Nature Astronomy and posted on the publication’s sister website, Nature, in an edition published last fall.
NASA’s OSIRIS-REx spacecraft visited the 65-million-year-old rubble-pile asteroid Bennu, collecting pristine material and returning it to Earth in late 2023. Unlike meteorites, which have been exposed to the atmosphere, these samples were sealed in an airtight container, so scientists could analyze them without contamination.
The analysis provided 14 out of the 20 amino acids required for life and all five nucleobases found in DNA and RNA. Researchers also discovered more than 10,000 nitrogen-bearing compounds, ammonia, and formaldehyde, which have been known to contribute to complex molecule formation. The presence of these elements is indicative of organic building blocks having been present within the early solar system and probably delivered to Earth via asteroid impacts.
Other than organic compounds, scientists also found evaporated brine minerals that show the parent asteroid of Bennu must have had liquid water. Among the minerals are sodium-bearing phosphates, carbonates, sulfates, chlorides, and fluorides which are crucial elements for life. This discovery favors the idea that such briny conditions could be still present on Ceres and Enceladus, whose subsurface oceans are thought to exist.
What makes Bennu’s samples even more significant is their pristine nature. Unlike meteorites, which are altered by Earth’s atmosphere, these samples remained untouched, preserving chemical details that would have otherwise degraded. According to NASA researchers, many of these findings would not have been possible without a sample-return mission, as Earth’s environment could have altered or destroyed these delicate organic compounds.
Scientists also found an interesting fact: the amino acids found in Bennu do not have the same left-handed bias that is present in terrestrial life. This would mean that they were formed through non-biological processes, which raises new questions about how the building blocks of life developed in the solar system.
These results confirm the indication that organic molecules were abundant in the early solar system and should have seeded life on Earth and perhaps other planets. But more discoveries are still in store for researchers, sifting through the Bennu samples as results are given. Several samples will be frozen for decades: one of them has been frozen at -80°C and is not scheduled for opening until 49 years from now to await technologies that can give an even deeper look.
