Salar de Pajonales: Mars analogue

Context of the News

Scientists studied Salar de Pajonales in Chile (Atacama Desert region) as an analogue of Mars.

The focus was on:

• Gypsum mineral (CaSO₄·2H₂O)

• Microbial structures called Stromatolites

• Implications for extraterrestrial life search

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🗺️ 2️⃣ Salar de Pajonales – Why Important?

Key Features:

• Located in the Atacama Desert

• Altitude: ~3.5 km above sea level

• Extremely dry (one of the driest places on Earth)

• High UV radiation

• Freezing temperatures

📌 UPSC Link (Geography):

• Atacama Desert = Coastal desert

• Rain shadow effect (Andes Mountains)

• Cold ocean currents (Humboldt Current)

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🧪 3️⃣ What is Gypsum?

Chemical Formula:

Calcium Sulphate Dihydrate (CaSO₄·2H₂O)

Properties:

• Translucent

• Contains water molecules

• Found on Earth and Mars

• Can preserve fossils

📌 UPSC Relevance:

• Mineral resources

• Evaporite deposits

• Indicators of past water presence

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🦠 4️⃣ Stromatolites – Why Important?

Definition:

Layered rock structures formed by microbial communities, mainly cyanobacteria.

Importance:

• Among the oldest evidence of life on Earth

• Act as biosignatures

• Preserve chemical fingerprints of life

📌 UPSC Link (Science & Tech + Evolution):

• Early life evolution

• Photosynthetic microbes

• Biosignatures in astrobiology

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🚀 5️⃣ Why This Study Matters for Mars?

Scientists already know:

• Mars has large gypsum deposits

• Past presence of water

• Harsh surface conditions

Two Major Findings:

1️⃣ Gypsum as Shield

• Allows sunlight in

• Blocks harmful UV radiation

• Traps moisture

2️⃣ Gypsum as Fossil Preserver

• Seals remains

• Preserves chemical biosignatures

Conclusion:

If life survived in Atacama gypsum, similar structures on Mars may preserve evidence of ancient microbial life.

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📚 UPSC Syllabus Mapping

🔹 GS Paper I

• Physical Geography (Deserts, Minerals)

• Earth’s evolution

• Geological formations

🔹 GS Paper III

• Space technology

• Astrobiology

• Remote sensing

• Scientific research

🔹 Prelims Areas

• Mineral composition

• Stromatolites

• Extreme ecosystems

• Mars exploration missions

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📝 6️⃣ Structured Notes for Revision (Exam Ready)

A. Analogue Environments

• Atacama Desert = Mars analogue

• Extreme aridity

• High UV radiation

• Low moisture

B. Gypsum Significance

• Hydrated mineral

• Indicator of past water

• Possible biosignature trap

C. Stromatolites

• Formed by microbes

• Oldest fossil records

• Important in oxygenation of Earth

D. Implications for Mars Missions

• Orbiter detection of gypsum

• Future rover missions may target gypsum deposits

• Search for preserved biosignatures

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🎯 7️⃣ 5 Practice PYQs (UPSC Level) with Explanation

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Q1. With reference to stromatolites, consider the following statements:

1. They are layered sedimentary structures formed by microbial activity.

2. They are found only in marine environments.

3. They represent some of the oldest evidence of life on Earth.

Which of the above statements is/are correct?

A) 1 and 2 only

B) 1 and 3 only

C) 3 only

D) 1, 2 and 3

✅ Answer: B

Explanation:

• Statement 1: Correct

• Statement 2: Incorrect (Also found in freshwater environments)

• Statement 3: Correct

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Q2. Gypsum deposits on planetary surfaces are considered significant because:

A) They indicate volcanic activity

B) They are metallic ores

C) They suggest the past presence of water

D) They emit methane

✅ Answer: C

Explanation:

Gypsum (CaSO₄·2H₂O) contains water molecules → forms in evaporative water conditions.

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Q3. The Atacama Desert is extremely dry primarily due to:

1. Cold ocean currents

2. Rain shadow effect

3. Equatorial location

Select the correct answer:

A) 1 only

B) 1 and 2 only

C) 2 and 3 only

D) 1, 2, and 3

✅ Answer: B

Explanation:

• Humboldt Current (cold current) reduces evaporation.

• Andes create a rain shadow.

• Not equatorial.

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Q4. Which of the following minerals is chemically classified as a hydrated sulfate?

A) Quartz

B) Gypsum

C) Hematite

D) Bauxite

✅ Answer: B

Explanation:

Gypsum = Calcium Sulphate Dihydrate.

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Q5. The term ‘planetary analogue site’ refers to:

A) A site used for satellite launching

B) A place on Earth that simulates conditions of another planet

C) A meteorite impact site

D) A volcanic region on Mars

✅ Answer: B

Explanation:

Analogue sites help test instruments and study life survival possibilities.

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🧠 Possible Mains Question

“Extreme terrestrial environments provide crucial insights into the possibility of extraterrestrial life.” Discuss with reference to recent studies in desert ecosystems.