Environmental Control and Life Support Considerations for a Human Mission to Near Earth Asteroids

Abstract

Near Earth Asteroids represent a potential destination for near-term human space exploration; Lockheed Martin conducted a study, dubbed Plymouth Rock, to investigate the feasibility of a human mission to Near Earth Asteroids using two Orion spacecraft joined at the docking ports. An asteroid mission will have a long-duration of 95-205 days. As the Environmental Control and Life Support (ECLS) Subsystem is a mass and volume driver for long-duration missions, the following paper identifies the design drivers and identifies potential solutions to the challenge within the Orion architecture constraints. Specifically, the study explored the ECLS design sensitivity to mission duration (120, 150, 180, and 210 days). For 120 to 180-day missions, the crew-related consumables (water, nitrogen, oxygen, and food) were shown to require additional tanks and volume above the baseline; the packaging analysis showed that these tanks should fit in the available volume of the Crew and Service Module. A 210-day mission exceeded the available volume between two Orions. The 210-day ECLS design challenge is not the driving constraint, because missions beyond Low Earth Orbit are usually duration limited to minimize radiation exposure of the crew. If radiation exposure was not a constraint, there are opportunities to lower the subsystem mass and enable a 210-day mission. The options include reducing the consumable requirements, while maintaining acceptable human performance limits, augmenting the Orion with proven technologies, or stretching the crew cabin of an Orion. In conclusion, the study of the ECLS subsystem for the Plymouth Rock mission concept found that an Orion platform can support a 180-day human mission to a Near Earth Asteroid.