CBSE Class 10 Answered

NASA scientists are learning how to grow plants in space. They hope that such far-out crops will eventually take their place alongside people, microbes and machines in self-contained habitats for astronauts.

Several precautions need to be taken in order to make this feat (i.e. growing of plants in space stations) possible.

In an orbiting greenhouse, freely-falling plants don't feel the constant downward pull of gravity. As a result, water spreads out evenly in the soil-like material around their roots, which makes it harder for both air and water to reach the roots. Researchers had to choose the size of the granules in the soil very carefully. If the grains are too big, the roots won't get enough water; if they're too small, not enough air. 

Also, there is less natural air circulation in an orbiting outpost -- plants can therefore suffocate on their own exhaled oxygen Designers have to provide fans to keep the air moving.

When building a greenhouse in space, the light source needs to be as efficient as possible to reduce energy demands. Light Emitting Diodes (LEDs) can be used as light source.LEDs save energy by only releasing light in frequencies that plants can use for photosynthesis

Advances in technology are also being used for making plants efficient to live in space stations. For example, foreseeable advances in biotech and nanotech could make it possible to alter plants' genes so that their cells produce little molecular sensors, transmitters, and receivers. These would monitor the plants internally and report on their health to ensure a good crop, and could even make the plants controllable, sprouting and flowering on cue. Another idea is to engineer plants to produce chemicals that protect them from the increased radiation in space and on planets with thin atmospheres, such as Mars. Also nanotech devices in the plants' cells could deliver light directly to the cell parts that perform photosynthesis, making the plants more efficient.