What Air and Water Quality Monitoring Is Needed to Protect Crew Health on Spacecraft?

Abstract

Abstract

Spacecraft are partially- or fully-closed environments that demand environmental monitoring to protect the health of the crew and the vehicle. This article will detail the history of air and water monitoring on U.S. spacecraft from early in the human spaceflight era and will use the lessons learned to project the needs for commercial crew vehicles and exploration missions. Many sources of air and water pollutants exist on spacecraft (e.g., humans, material off-gas products, system chemicals, and experiments), which are scrubbed by various Environmental Control and Life Support Systems (ECLSS). Environmental monitoring is important because the rate of removal seldom, if ever, equals or exceeds the rate of generation. As an example, carbon dioxide levels are “controlled” in spacecraft, but the levels are never close to zero. Much of the recycled water comes from spacecraft air condensate; therefore, contaminants in the air can also have a dramatic effect on potable water reclamation/purification and resulting water quality. In addition, potential system leaks and spills can contaminate the air and/or water. The experiences of humans working in closed environments (spacecraft and submarines) show that engineering controls are not sufficient to completely protect the crew from environmental hazards. This article will highlight the fact that characteristics of environmental monitors go beyond being lower power and small instruments. How much monitoring is required and the characteristics of the monitors all depend on the mission scenario, particularly mission durations and the ability of the crews to return to Earth or seek safe haven in the event of environmental contamination of their primary vehicle.