Design, Construction and Operation of an Experimental Plant Chamber Using Proportional and PID Temperature Control

NASA's Centrifuge Facility is a multi-purpose life sciences research facility to be flown on Space Station Freedom. It will provide the capability for conducting experiments with living plants and animals in the microgravity environment of space. One component of the Facility is a plant habitat which is capable of supporting a wide variety of plant species under highly controlled environmental conditions. The conditions to be controlled include temperature, humidity, lighting (photosynthetically active radiation or PAR), air velocity, trace contaminant concentrations, nutrient element concentrations, and atmospheric composition. Lockheed conducted a “rapid prototyping” exercise to develop and test a preliminary design for such a plant habitat. Concurrent with an analytical effort, breadboard fabrication and testing was performed to support the acquisition of detailed performance data for both design analysis and validation of the simulation models used in the analysis. This paper describes the design, some of the computer simulation models developed, the control algorithms tested, and the software environment used. The results of the breadboard performance tests are presented. Finally, the lessons learned from this exercise are discussed for possible application to future rapid prototyping efforts in the development of similar Life Sciences flight hardware.