Advanced Plant Habitat

The Advanced Plant Habitat (APH) is a fully automated plant growth facility that is used to conduct fundamental plant research or other bioscience research on the ISSInternational Space Station. APH is configured as a quad-locker payload and occupies the lower half of the EXpedite the PRocesssing of Experiments to Space Station (EXPRESS) Rack and one powered International Subrack Interface Standard (ISIS) drawer, providing an enclosed, environmentally controlled chamber. APH provides a window for the crew to view plant growth progress while maintaining the single level of containment.

The APH hardware contains more than 180 calibrated sensors to provide autonomous function using a pre-programmed experimental design that provides a sufficient growth environment (e.g., carbon dioxide levels, light intensity, spectral quality, temperature, and relative humidity) for a plant experiment for up to 135 days. The growing space can accommodate a shoot area of 1,708 cm2, a shoot height of 43 cm, a root area of 1,853 cm2, and root height of 5 cm. It contains an active thermal control system, using thermoelectric coolers to heat and cool the air inside the shoot zone with a range of 18 °C to 30 °C and an accuracy of +/- 0.5 °C. The temperature uniformity in the plant canopy plane is +/- 1 °C. The relative humidity can be set from 50% to 90% and is accurate within +/- 3%. Furthermore, the APH contains sensors capable of measuring light levels in the photosynthetically active and red/far red ranges and the surface temperature of a plant canopy or other sample surface. In the root zone, APH can measure temperature, moisture levels, and oxygen content.

APH uses the following lights: high-intensity red (0-600 µmol m-2 s-1 at 630-660 nm ±10 nm), blue (0-400 µmol m-2 s-1 at 400-500 nm ±10 nm), green (0-100 µmol m-2 s-1 at 525 nm ±10 nm), broad spectrum white (0-600 µmol m-2 s-1 at 400-700 nm), and far-red (0-50 µmol m-2 s-1 at 730-750 nm ±10 nm).

Porous tubes are used for active water-nutrient delivery through a rooting matrix. The atmospheric composition of CO2 is 400 ppm to 5,000 ppm +/ 50 ppm. An EXPRESS-Rack-compatible data/photo interface allows for real-time data telemetry, remote commanding, and photo downlink.