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CROPS: A Milestone in Space Biological Research
Context:
The Compact Research Module for Orbital Plant Studies (CROPS) is an experimental module developed by ISRO to explore plant growth in microgravity.
- It aims to ensure sustainable food production in space and enhance astronaut engagement during long-duration mission.
What is CROPS?
- CROPS stands for Compact Research Module for Orbital Plant Studies, an unmanned experimental module for growing plants in space.
- It is an airtight container simulating Earth-like conditions, excluding gravity, to study plant growth.
Key Features of CROPS-1:
- Dimensions: 300 mm diameter and 450 mm height.
- Soil Medium: Neutral, highly porous clay pellets premixed with slow-release fertiliser for controlled nutrient delivery.
- Seed Preparation: Seeds were sterilised with ethanol, pasted to a polypropylene tissue using organic gum, and inserted into the soil.
- Environmental Conditions: Maintained at 20-30°C, with 20.9% oxygen, 400–600 ppm CO₂, and 50–60% humidity.
- Water Supply: Pure water stored in a pressurised tank and delivered via electric valve and capillary action.
- Illumination: LEDs (warm and cool) provided 16-hour light and 8-hour darkness for photosynthesis.
Objectives and Achievements of CROPS-1:
- Objective: Demonstrate seed germination and plant growth up to the two-leaf stage in microgravity within 5–7 days.
- Plant Chosen: Cowpea (Vigna unguiculata) due to its short germination time.
- Success: Seeds germinated by the fourth day, and two leaves were visible by the fifth day, achieving all objectives.
Methods of Growing Plants in Space:
- Hydroponics: Plants are grown in a liquid solution that delivers water and nutrients, without the need for soil.
- Aeroponics: Plants are grown in air, with minimal water and no soil. This method reduces water use by 98%, fertiliser by 60%, and eliminates pesticides.
- Soil-like Media: Some plants are grown in media that mimics soil, such as the method used by ISRO.
Characteristics of CROPS-1 Experiment:
- Mini Greenhouse: Maintained Earth-like air and temperature.
- High Precision: Sensors monitored carbon dioxide, oxygen, temperature, and soil moisture.
- Controlled Illumination: LEDs simulated day-night cycles for optimal plant growth.
- Robust Design: Vibration isolators protected the module during launch.
Ideal Plants for Space Farming:
- Leafy greens (lettuce, spinach, kale) are ideal due to their quick growth, minimal space requirement, and high nutrient content.
- Beans and peas are useful for protein and for fixing nitrogen, enriching the medium.
- Radishes and carrots are compact and grow well in space.
- Wheat and rice are suitable for long-term sustenance.
- Tomatoes and strawberries are also viable for cultivation.
Challenges:
- Microgravity: The lack of gravity makes it difficult for plant roots to grow downward, and water does not flow to the roots efficiently. Nutrient delivery is challenging, and radiation can damage plant DNA.
- Light Conditions: Limited light, especially in outer space, can hinder photosynthesis, causing plants to consume more oxygen than they produce.
- Temperature Fluctuations: Space experiences extreme temperature variations.
Significance of Growing Plants in Space:
- Sustainability: Provides a reliable food source for long-duration missions, reducing dependency on resupply missions.
- Oxygen Production: Plants release oxygen through photosynthesis, maintaining a breathable atmosphere.
- Mental Health Benefits: Tending to plants reduces stress and improves astronauts’ well-being.
- Closed-Loop Life Support: Plants recycle carbon dioxide and organic waste, creating a sustainable ecosystem.
Future of CROPS and Space Farming:
- Longer Missions: Future CROPS experiments aim to sustain plant growth for 30–45 days, supporting life beyond the two-leaf stage.
Advanced Controls: Active regulation of humidity, oxygen, carbon dioxide, and soil moisture is planned for extended experiments.
