Lunar Habitat Airlock/Suitlock

Abstract

Airlocks for lunar Extravehicular Activity (EVA) will be significantly different than previous designs. Until now, airlocks operated infrequently and only in the "clean" weightless environment, but lunar airlocks are planned to be used much more often (every other day) in a dusty, gravity environment. Concepts for airlocks were analyzed by the NASA, JSC Habitability Focus Element during recent lunar outpost studies. Three airlock types were identified; an Airlock (AL) or independent pressure vessel with one hatch to the outside and the other to the Habitat. A Suitlock (SL) which shares a pressure bulkhead with the Habitat allowing rear-entry suits to remain on the dusty side while the crew enters/exits the Habitat. The third option is the Suitport (SP) which offers direct access from the habitable volume into an externally mounted suit. The SP concept was not compared, however between the AL and SL, the AL was favored. IntroductionMost people are surprised that EVA for all the 6 lunar landings was done without an airlock. In fact, it wasn't until after the Apollo Program, during Skylab, that Americans included their first airlock on a spacecraft. The early programs could not accommodate the additional weight, power and volume required for airlocks. Since then, the Shuttle and International Space Station have included airlocks that are designed for EVA in a clean, weightless environment. Weightless hatches are round, but hatches in the gravity environment must accommodate a walking astronaut looking more like submarine hatches. Furthermore, the experience from Apollo exposed the hazards of bringing the abrasive lunar dust into the pressurized volume. It affects crew health, spacecraft cleanliness along with the operation of pumps, filters, seals, and hinges.For this study, the term, airlock represents the inclusive class of pressure vessels used for moving EVA crew and cargo between the lunar surface and the habitable volume. The acronyms AL and SL depict different airlock concepts. ObjectivesThe following objectives were established to create common ground for comparison: 1. Minimize loss of resources (air), 2. Design for simple and safe operations, 3. Stress commonality (e.g., with ascent/descent vehicle and pressurized rover), 4. Minimize overall program mass, 5. Minimize the intrusion oflunar dust, and 6. Accommodate the transfer of crew, cargo and an incapacitated crew member.

In Situ Optimized Substrate Witness Plates: Ground Truth for Key Processes on the Moon and Other Planets

“…We use an extravehicular activity on the International Space Station (ISS), where the crewlock section of the airlock is depressurized, as an analog for potential lunar south pole surface EVAs. While airlocks and suitlocks that may be or have been used in the future (Griffin, 2008;NASA EVA, 2018) will have different means of depressurization and protocol prior to an EVA, and consequently will have different vented mass estimates, this scenario gives a real-life analog, we can study that has crewlock dimensions, depressurization details and details regarding contamination limits for air quality requirements all given in citeable literature. Crewlock dimensions, operations, and depressurization details are taken from D. E. Williams et al (2004) while air quality requirements that we use to estimate maximum potential contaminant masses are taken from Table 32 of Wieland (1998).…”