Subject & Paper: GS-3 (Science & Tech/Space), Prelims

What happened 

NASA’s Perseverance rover reported possible biosignatures in rocks of Jezero Crater, an ancient lake bed. Scientists observed ring-like “leopard-spot” textures and certain minerals (notably vivianite and greigite) that, on Earth, can form in environments affected by microbes. The team is careful: this is not proof of life. Similar features can arise without biology. To be sure, the drilled cores need to be brought to Earth for lab tests.

Why it matters.
Jezero once held standing water—the best natural “storage” for chemical clues. If any ancient microbes ever lived on Mars, their chemical fingerprints could be preserved in these fine-grained rocks. Confirming or rejecting biological origins will shape our understanding of life beyond Earth and informs the broader “Where is everybody?” puzzle (the Fermi paradox): life may be rare, or its traces simply hard to prove.

Simple glossary 

• Biosignature: A clue that is consistent with life (e.g., certain organic molecules, mineral patterns, or textures) but not proof by itself.
  
• Mudstone: A fine-grained sedimentary rock formed from mud (silt + clay) settling in calm water—good at trapping and preserving chemical signals.
  
• Vivianite (iron phosphate) & Greigite (iron sulfide): Minerals that can form in low-oxygen, watery settings. On Earth, they sometimes involve microbial processes, but can also form abiotically.
  
• Leopard-spot texture: Ringed or spotted patterns in rock; can be made by biology or by pure chemistry.
  
• Caching: Perseverance drills pencil-like cores, seals them in titanium tubes, and stores/deposits them for a future Mars Sample Return mission.

Read it right (why caution is essential).
Mars instruments on a rover are small and remote; they can screen but not settle the question. Earth labs can do isotope ratios, micro-imaging, contamination checks, and tests that need large, delicate instruments. Hence: “possible biosignature” ≠ “life found.”

What to remember for Prelims:

• Perseverance is exploring Jezero Crater and caching cores.
• Biosignature means maybe, not proof.
• Vivianite/greigite can be made with or without biology
• Sample return is the gold standard to confirm or refute life.

Prelims Question
Which pair is correctly matched?
A. Vivianite/greigite in mudstones — may form with or without biology
B. Leopard-spot textures — conclusive proof of microbes
C. Cached cores — enable Earth-based tests for confirmation

(a) A and B only (b) B and C only (c) A and C only (d) A, B and C

Answer: (c) A and C only.

One-line wrap: Promising clues from Jezero—treat as “maybe,” and bring the rocks home to be sure.