University uses Mass Flow Controller for "Out of This World" Research

In their studies of biological life support for future space exploration, researchers at the University of Guelph’s Controlled Environment Systems Research Facility (CESRF) are using Sierra's Smart-Trak® Model 100 Digital Mass Flow Controllers (MFCs) to control plant growth environments in hypobaric chambers.

The pressure on Mars is less than one percent of what it is on Earth, and the CESRF research includes evaluation of plant growth under these low atmospheric pressures. Their experiments utilize eight closed-loop hypobaric chambers. Each of these chambers is equipped with three MFCs to flow carbon dioxide, oxygen, and nitrogen into the controlled environment.

The carbon dioxide mass flow measurement is used to calculate the rate of photosynthesis, and the oxygen and nitrogen MFCs are used to maintain the partial pressures of those gases, as required by the experiments. Essentially, by changing specific parameters, such as light, CO2 concentration, pressure, and/or temperature, the rate of photosynthesis can be varied.

CESRF researchers originally used flow-tube style flow meters to control gas injection rates, but found that they were unable to provide the required accuracy under fluctuating temperature and pressure conditions. Dr. Michael Stasiak, a principle researcher at CESRF, says that accuracy is the greatest benefit of using MFCs for low-flow gas delivery. “I have grown plants for 120 days in a sealed growth chamber, and the difference between the carbon added by the MFC as carbon dioxide and the amount of carbon in the plants at the end of the experiment has been as little as five percent,” he says.