circadian space


Class Objective
To design a plant growth system on the International Space Station (ISS) that will confer lifestyle benefits to astronauts in space

Project Goal
Develop a growth and maintenance system for a plant that will help regulate astronauts' circadian clock
Due to lack of a light-dark environment in space, it is difficult for astronauts to entrain their biological clocks to a 24-hour rhythmic cycle. Insufficient regulation of a circadian clock can result in impaired performance accuracy due to fatigue and reduced alertness from an unregulated sleep cycle. Studies on shift workers have also shown that an unregulated clock can also result in long-term deficits such as brain degeneration and cancer. Based on these findings, we decided that designing a growth system for a melatonin-producing plant could offer a solution for this problem on the ISS.

 3D Digital Modeling - Rhinoceros 5.0
 Diagrams - Adobe Illustrator & Photoshop
 Research - all articles referenced from PubMed
Plant Research/Concept Development
Melatonin is a neurohormone naturally produced in the pineal gland in humans, and its secretion is regulated by light induced activity in the suprachiasmatic nucleus (SCN). The presence of a 24 hour light-dark environment regulates melatonin secretion, where darkness activates and light suppresses its release. However, individuals who lack exposure to a regular 24 hour light-dark cycle or possess insensitivity to visual cues in their environment can take melatonin as a plant drug supplement.
Melatonin productionScutelleria baicalensis
Based on a number of studies and references, S. baicalensis produces the highest melatonin concentration amongst any naturally-growing plant (7µg/g). The plant is commonly used in traditional Chinese medicine (known as huang qin, 黄芩) and its medicinal properties are extracted from the root. Approximately 90% of all plants on earth thrive through a symbiotic plant-fungi association called a mycorrhizae. This symbiotic relationship contains a sugar/water-mineral exchange and is visualized in the diagram below.
Mycorrhizae symbiontArmillaria mellea
A. mellea is a fungal species that emits bioluminescence. For growth optimization, we plan to control the timing/cycle of bioluminescence emittance so that it adjusts the circadian rhythm of our melatonin-producing plant, S. baicalensis. Although most chlorophyll producing plants tend to be sensitive to red light, we plan to inject green-light sensitive photoreceptors (opsin 1, OPN1MW) into the leaves of S. baicalensis, in order to control its circadian clock. We will regulate the bioluminescence-emitting cycle of A. mellea for maximal S. baicalensis growth.
Mycorrhizae - plant-fungi symbiosis
24-hour bioluminescence cycle. When bioluminescence emittance of A. mellea is greatest in intensity, glass tint maximally increases in opacity to allow for optimized photosynthesis for S. baicalensis.
Pathway from plant ingestion to downstream effects of circadian regulation in human organs
Plants will be grown on a gellan gum matrix along the ceiling and walls of the ISS module. The matrix contains mechanical touch sensors detecting stages in plant growth (by sensing weight change in the roots) and readjusts in shape and thickness to accommodate changes in physical support at various stages of growth. As the ISS contains a micro-gravitational environment, this system allows plants to grow in various directions without spatial constraint.

Glass panes adjust in translucency depending on the bioluminescence-emitting cycle (see diagram above). Panes appear darkest (no light filtration) when bioluminescence is most intense, so as to maximize light exposure to S. baicalensis.

This project was completed as part of a two-person team. Biology and architecture students were paired together and required to divide up research, modeling, and presentation.

Collaboration with Sandra (Hae Rin) Moon