Purge System

The Purge Systems' role is to provide an inert, dry, clean, thermally conditioned gas flow to the Upper Stage compartments while Ares is on the launch pad.  Nitrogen, a non-combustible gas, is pumped into the closed compartments to prevent hydrogen or oxygen from accumulating to dangerous levels. Excess nitrogen is exhausted

Instrument Unit

through special vents at the bottom of the compartments. The purge system increases the safety of pre-mission operations by preventing conditions that could lead to a fire or an explosion.

Hazardous Gas Detection System

Another safety device used on the launch pad is the Hazardous Gas Detection System which was designed after the existing Space Shuttle system. Three of these independent detection systems provide the capability to sample, detect, and measure the concentration of hazardous gases in the Upper Stage compartments prior to launch.  Glenn is developing the tubing that the system uses to extract the gas samples. The tubes transport the gas to the mass spectrometer, which performs the content analysis.