NASA Scientists Find All the DNA Nucleobases and 14 out of 20 Amino Acids in Bennu Asteroid Samples. They’re the Key Molecules for Life

  • Key blocks of life may have been present throughout the solar system from the very beginning.

  • This discovery is as thrilling as you could expected from a 4.5-billion-year-old asteroid.

Bennu sample
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Matías S. Zavia

Writer
matias-s-zavia

Matías S. Zavia

Writer

Aerospace and energy industries journalist. LinkedIn

167 publications by Matías S. Zavia

NASA successfully opened the Bennu asteroid capsule in January 2024. A year later, scientists released their analysis, and the results were as exciting as you could expect from a 4.5 billion-year-old asteroid.

OSIRIS-REx and the Bennu asteroid. Launched in 2016, the OSIRIS-REx probe completed one of NASA’s most ambitious missions in recent years. In 2018, the probe reached the near-Earth asteroid Bennu, where it spent several months mapping and analyzing it closely before descending to touch its surface.

In 2020, OSIRIS-REx collected 121.6 grams of samples from Bennu. It then began its return journey and successfully released the samples on Earth in September 2023. Although the amount collected was less than scientists expected, it still marks the most samples ever brought back from a celestial body other than the Moon.

The samples are also a true time capsule, reflecting the asteroid’s age of 4.5 billion years, nearly as old as the solar system itself.

What’s in the Bennu samples? The findings from the Bennu samples have been published in two studies in Nature and Nature Astronomy. The results reveal that the 121.6 grams of material brought back by OSIRIS-REx contains key molecules for life. They also show evidence of a salty environment that may have contributed to its formation.

Key discoveries include:

  • Amino acids and nucleobases. The samples contain 14 of the 20 amino acids that living organisms use to create proteins, as well as all five nucleobases that form the building blocks of DNA and RNA, the genetic material of life on Earth.
  • Ammonia and formaldehyde. Ammonia is crucial for chemical reactions that produce complex molecules. When combined with ammonia, formaldehyde can form amino acids.
  • Salts and salt water. The presence of minerals formed from the evaporation of brine suggests that Bennu may have once possessed an environment conducive to prebiotic chemistry.
Bennu sample

What this finding implies. The discovery of these molecules supports the idea that the essential ingredients for life may have been distributed throughout the solar system early in its history. Scientists have known asteroids to deliver water to Earth. It stands to reason that they could also bring other building blocks of life or even microbial life itself. It’s possible that the conditions for life existed in various other regions of the solar system.

The material collected from Bennu contains a mix of salts, including calcite, halite, trona, and sylvite, which have only been partially observed in some meteorites. This suggests that the body from which Bennu originated likely had water and the necessary conditions for the formation of organic compounds.

What this finding doesn’t imply. The fact that Bennu’s “parent” has conditions suitable for life doesn’t mean scientists have discovered life on an extraterrestrial body. The samples collected don’t contain evidence of living organisms and don’t confirm the existence of extraterrestrial life in any way.

The material formed in a cold region of the solar system beyond Jupiter’s orbit. While it doesn’t completely answer the question, it does provide some insight into the larger inquiry of whether there are scenarios conducive to life beyond Earth. Importantly, the samples are free from terrestrial contamination, unlike those from the Ryugu asteroid, which were collected by the Japanese Hayabusa 2 mission.

Moving on to other asteroids. Earth’s laboratories are currently the best resources for analysis. None of this would’ve been possible without the complex sample recovery mission. OSIRIS-REx is the third one, following the Japanese Hayabusa missions. China will soon launch the Tianwen-2 mission, which will travel to asteroid 2016 HO3 Kamoʻoalewa.

Image | NASA

Related | Physicists Have Been Searching for a Fundamental ‘Fifth Force’ for Decades. The Bennu Asteroid May Have Brought Them Closer to Finding It

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