Grow Plants In Space
The cargo just delivered to the International Space Station by the SpaceX Dragon ship contains another batch of thale cress plants. A small flowering plant related to the cabbage, the thale cress is being used to study the gravity-sensing abilities of plants in space.
Gravitropism, the ability of plants to sense gravity, enables them to grow by sending nutrients to the stalks, in the opposite direction from their roots. It was first discovered by Thomas Hawkins over 200 years ago, and elucidated by Charles Darwin. But it is not clear how these mechanisms function in the microgravity situation of space habitats.
The Plant Gravity Sensing experiment conducted by the Japanese space agency on board the ISS focuses on identifying the molecular mechanism of gravitropism. In other words, it seeks to identify the chemical changes occurring in plants at the molecular level, as they find their direction of growth in microgravity. The study also looks at the molecular changes when plants grown in microgravity make the transition to earth gravity.
The second run of the experiment will follow the chemical changes occurring at the molecular level in the plants under microgravity. Among other things, the experiments look at the changes in Calcium levels under microgravity conditions, measuring the concentration of calcium in plant cells and how it changes in response to changing gravity conditions. Such experiments are difficult to carry out on earth, where it is difficult to change or modify gravity, due to the presence of earth’s gravity.
According to Hitoshi Tatsumi, principal investigator of the Plant Gravity Sensing experiment,
“Plants cultivated in space are not experienced with gravity or the direction of gravity and may not be able to form gravity sensors that respond to the specific direction of gravity changes.”
Thale cress was chosen for the study because it is considered a model organism for biological research, since there are genetic similarities to other organisms. Test results will have implications for human health in space as well. In particular, it will offer insights into gravity-related space disorders such as osteoporosis and muscle loss.
The experiments are important in terms of preparation for long-term spaceflight to Mars and the asteroids, which will have to grow food on board.
