Among plant growth experiments were Astroculture, flying for fourth time on Shuttle. The objective of Astroculture was to validate performance of plant growth technologies in the microgravity environment of space for application to a life support system in space. The investigation had applications on Earth, since it covered such topics as energy-efficient lighting and removal of pollutants from indoor air. One of the pharmaceutical experiments, Immune, also had Earth applications. Exploiting a known tendency of spaceflight to weaken the immune system, Immune experiment tested the ability of a particular substance to prevent or reduce this weakening. Clinical applications could include treatment of individuals suffering from such immunosuppressant diseases as AIDS.