How and why are plants grown in space: Takeaways from ISRO’s success

Sub: Sci

Sec: Space sector

Context:

The lobia (black-eyed pea) seeds that the Indian Space Research Organisation (ISRO) sent to space as a part of its Compact Research Module for Orbital Plant Studies (CROPS) germinated last week.

Why grow plants in Space:

This experiment demonstrates the potential for space-grown plants to provide sustainable food sources for long-term space missions to Mars and the Moon, where resupplying food is limited.
Plants can also help create a closed-loop life support system by recycling carbon dioxide and waste, while also improving astronauts’ mental well-being.

Challenges of Growing Plants in Space:

Microgravity: In the absence of gravity, plant roots struggle to grow downwards, and nutrient delivery becomes difficult. Water behaves differently in microgravity, sticking to surfaces and not trickling down to the plant roots as it would on Earth.
Radiation and Temperature Fluctuations: Plants in space are exposed to high levels of radiation, which can damage their DNA and hinder growth. Additionally, space’s extreme temperature fluctuations, often reaching hundreds of degrees, require special insulation to protect the plants.
Light Conditions: In regions of the outer solar system where sunlight is scarce, providing adequate light for photosynthesis is challenging. Without light, photosynthesis stops, and plants begin to consume more oxygen than they produce.

Methods of Growing Plants in Space:

Hydroponics: Hydroponics is the most common method used to grow plants in space. In this system, plants are grown without soil, with water and nutrients delivered via liquid solutions.
Aeroponics: Aeroponics is another method where plants are grown without soil, using a mist of water and nutrients. This method uses 98% less water and 60% less fertilizer compared to traditional methods. It has the added benefit of eliminating the need for pesticides.
Soil-Like Media: Plants can also be grown in space using soil-like media, such as the highly porous clay pellets used by ISRO in its recent experiment. These pellets help retain water and release nutrients slowly.

ISRO’s Space Experiment with Lobia:

ISRO’s CROPS experiment was conducted using a mini greenhouse-like module.
The soil-like medium used by ISRO consisted of highly porous clay pellets. These pellets had a water-activated slow-release fertilizer to provide nutrients to the plants over time.
ISRO used warm and cool LEDs to simulate sunlight. The lights were programmed to be on for 16 hours and off for 8 hours to mimic day and night cycles.
Temperatures inside the module were regulated between 20 and 30°C, and water was injected into the soil-like medium through an electric valve operated from Earth.
The lobia seeds sprouted on the fourth day of the experiment, with two leaves visible the following day, signalling the successful germination and initial growth of the plants in space.

Ideal Plants for Space Farming:

Plants suitable for space farming are selected based on their growth rate, nutrient content, and compatibility with space farming systems.
Leafy Greens: Lettuce, spinach, and kale are ideal for space farming as they grow quickly, require little space, and are rich in nutrients.
Legumes: Beans and peas are protein-dense and can fix nitrogen in the soil-like medium, improving nutrient cycles.
Root Vegetables: Radishes and carrots grow well in compact spaces.