BioTube generic containment unit (Credits: NASA).

The BioTube-Magnetophoretically Induced Curvature in Roots (Biotube-MICRO) experiment, similar to an experiment lost in the Columbia accident, will get a flight opportunity to the International Space Station (ISS). BioTube-MICRO investigates how the gravity sensing systems in organisms and plants operate. It provides insight into how plants grow, how plants detect and respond to gravity, and how the gravity sensing system of plants operates. Scientists are interested in the effects that the lack of gravity has on the direction plant roots grow. It is not clear whether the distribution of subcellular starch grains or their position in columella cells, are responsible for the direction of growth; therefore, the experiment uses a magnetic field to investigate which cells are responsible for the growth direction of plants in a microgravity environment.

“Right after the germination, the roots decide which way to grow. So the entire experiment is really interested in about the first 48 hours of how these roots grow when they are subjected to a magnetic field with no gravity,” Don Platt, president of Melbourne, Fla.-based Micro Aerospace Solutions which is developing BioTube-MICRO, told SpaceNews.

BioTube-MICRO, which is about the size of a microwave oven, uses strong magnets to displace the starch grains. On Earth, starch grains settle under gravity and in its absence they respond to an external magnetic field. If the displacement of the starch grains is the trigger for the gravity-sensing system, the root will bend away from the magnetic field. In addition to the in-flight observations, postflight studies are to be conducted to investigate the position of starch grains in columella cells. The combined data will further advance the study of how plants detect gravity.

The BioTube-MICRO experiment is a follow up to the Biotube experiment which was lost aboard STS-107, the last flight on the Columbia, which was destroyed during reentry in 2003, killing all seven astronauts onboard.

The experiment’s results will contribute to an enhanced understanding of how plants grow, which has important implications for improving plant productivity and yield on Earth. Biotube-MICRO is scheduled to fly on ISS Expedition 37/38, scheduled to begin in September 2013.