Context:
Recent laboratory studies of asteroid samples returned to Earth have provided compelling evidence that key biochemical building blocks of life existed in space well before the formation of Earth, reshaping scientific understanding of life’s origins.
Key Highlights:
- Mission / Scientific Background
- In 2020, the NASA’s OSIRIS-REx mission collected surface samples from the asteroid Bennu.
- The samples were successfully delivered to Earth in September 2023, enabling advanced laboratory analysis.
- Major Chemical Discoveries
- Detection of ribose and glucose, crucial sugar molecules linked to RNA formation and cellular metabolism.
- Confirmation of all molecules believed necessary for life, including:
- Amino acids
- All five nucleobases required for RNA and DNA.
- Discovery of carbamate, a nitrogen- and oxygen-rich compound, identified for the first time in extraterrestrial material.
- Presolar and Stellar Evidence
- Bennu contains an exceptionally high concentration of presolar grains, at least six times higher than in comparable asteroid and meteorite samples.
- Many grains originated from supernova explosions, predating the Sun’s formation.
- Indicates Bennu preserved ancient stellar material largely unaltered.
- Formation & Chemical Evolution
- Bennu’s parent body likely formed ~4.6 billion years ago, beyond Saturn’s orbit, before being displaced inward due to Jupiter’s migration.
- Radioactive decay may have liquefied icy volatiles, enabling chemical reactions that formed polymer molecules inside rocky pores.
- Significance / Scientific Implications
- Strongly supports the ‘RNA World’ hypothesis, suggesting RNA preceded DNA and proteins in early life.
- Reinforces the idea that life’s ingredients are cosmic, not Earth-exclusive.
- Raises new questions on whether Bennu is unique or representative of other asteroids.
Relevant Prelims Points:
- RNA World Hypothesis: Early life relied on RNA for genetic and catalytic functions.
- Presolar Grains: Solid particles formed before the Solar System.
- Supernova Dust: Source of heavy elements essential for complex chemistry.
- Amino Acids & Nucleobases: Fundamental biochemical components of life.
Relevant Mains Points:
- GS 3 (Science & Technology): Astrobiology, space missions, and origin-of-life research.
- GS 1 (Physical Geography): Solar System evolution and planetary migration.
- Interdisciplinary Linkages: Astronomy–chemistry–biology convergence.
- Ethical & Philosophical Dimension: Expands understanding of life beyond Earth-centric models.
Way Forward
- Comparative analysis of samples from other asteroids and comets.
- Integration with astrochemical models of early Solar System evolution.
- Strengthening planetary sample-return missions to refine origin-of-life theories.