How is Group Captain Shukla growing Moong Dal in ISS without sunlight?

 

Have you wondered how Group Captain Shukla is growing Moong dal without sunlight in the International Space Station (ISS)? Is there some artificial way to create sunlight for photosynthesis? Or does he let in sunlight from the spaceship's porthole?

It turns out astronauts use LED grow lights, which are specially tuned to provide the wavelengths of light that plants need—mainly blue and red light. These lights mimic the solar spectrum required for photosynthesis without needing to use actual sunlight. This is how plants are successfully grown in space, including on the International Space Station (ISS).

Red light (around 660 nm) promotes flowering and fruiting.

Blue light (around 450 nm) helps with leafy growth.

Sometimes, green or white light is added so astronauts can visually assess the plants.

Why not just use sunlight through a porthole?

While sunlight does reach spacecraft in orbit, letting it in through windows is not reliable or controlled. The spacecraft is constantly orbiting Earth (~90 minutes per orbit), leading to alternating periods of daylight and darkness. The intensity of sunlight in space is very strong and not easily adjustable. Direct sunlight can also cause overheating or UV damage.

So, it's far more efficient and controlled to use artificial lighting in a self-contained growth chamber.

If an Indian astronaut (say, on board the Gaganyaan mission or an ISRO experiment) is growing moong dal, s/he is likely using a sealed plant growth chamber, LED arrays mimicking sunlight, controlled temperature, humidity, and CO₂ levels.