Conducting research to assess the impact of microgravity on plant growth and development requires a plant growth unit that has the capability to provide an enclosed, controlled environment chamber. Since plants are sensitive to a number of atmospheric gaseous materials, the chamber's atmosphere must be isolated from the space vehicle atmosphere. The plant growth unit must also be capable of removing any deleterious materials that may affect plant growth and development. The ASTROCULTURE™ plant growth unit (ASC-8), developed by Wisconsin Center for Space Automation and Robotics (WCSAR) at the University of Wisconson, was used to provide the desired environmental conditions required to support plant growth experiment during 9-day STS-95 mission. Effective control of chamber temperature, chamber humidity, plant water and nutrients delivery, and chamber carbon dioxide was maintained during the entire mission. Ethylene was removed from the plant chamber atmosphere using a non-consumable photocatalytic oxidation unit. Light was provided by a light emitting diode (LED) unit that produced photons in the red and blue regions of the visible light spectrum. The wavelengths of the red and blue LEDs were specified to meet plant chlorophyll and photomorphogenic requirements.