Pressurized Rover Airlocks

The ability for crewmembers to explore the surface of the Moon or Mars effectively on foot remains a significant test of any exploration design. The availability of a pressurized rover would substantially increase the range of exploration by space suited crewmembers. The design of the airlock systems or functions will facilitate crewmembers in accomplishing these efforts. The pressurized rover for planetary exploration incorporates three types of airlocks or pressure ports: the EVA airlock, the sample airlock and the habitat docking port. This paper conducts a survey of selected precedents in pressurized rover design and then analyzes the key issues for airlock design. INTRODUCTION: THREE ENVIRONMENTS -THREE AIRLOCKS The airlock is the physical interface between the three working environments for crewmembers on the lunar or Mars surface. These environments are: the pressurized habitat in which the crew will live and work; the lunar/planetary surface and its atmosphere that require astronauts to wear space suits and carry their own life support; and the pressurized rover that gives them mobility over the surface. All three of these environments intersect in the pressurized rover. Thus, the pressurized rover for planetary exploration incorporates, at a minimum, three types of airlocks or pressure port functions: EVA egress and ingress, scientific sample ingress and removal, and docking or berthing to the pressurized habitat at the planetary base. Each of these three airlocks provides its own unique function that probably cannot be combined into a smaller number of devices. The EVA airlock enables spacesuited astronauts to egress and reenter the rover. The sample airlock provides the connection through which EVA crewmembers pass samples they have collected for analysis in the Astrobiology glove box, inside the rover. The habitat docking port is the connection through which the rover “docks” to the pressurized modules at the planetary base, and through which shirtsleeve crewmembers enter and exit the rover. REVIEW OF ROVER CONCEPTS & REQUIREMENTS In conducting this literature survey, the author began with the Apollo era studies such as the Lockheed MIMOSA study (1966-67) and the Boeing LESA study (1964-66). However, there was a remarkable 20 year hiatus between those studies in the mid-60s and the new flood of concepts that followed the landmark1984 conference on Lunar Bases and Space Activities of the 21st Century at the National Academy of Science in Washington DC (Mendell, 1985). This Conference set the philosophical agenda for human space exploration for at least the next 15 years, envisioning the return to the Moon and going on to Mars as one programmatic continuum. Beginning this review in the 1980s makes it possible to assume a common set of mission objectives and technologies, or at least an awareness of them on the part of the designers. The different approaches to these designs and technologies are significant for understanding why particular rover designs have certain attributes and lack others. Despite this sweep of time, the literature survey reveals surprisingly few serious studies of rover airlocks. Most airlock studies look at airlocks in general, in connection to Space Station or some other orbital vehicle. Thus, in selecting concepts from the literature for this review, it was a goal to find studies that address of airlocks, while including as many science-driven concepts as possible. From a design methodology perspective, this survey groups the pressurized rover concepts into three types of design approaches or sources: science-driven, mission architecture-driven, and system analysis-driven. TABLE 1 provides a comparative overview of the salient characteristics of each of the selected pressurized rover concepts that this paper discusses. These sets of requirements appear here much as they occur in the literature, with no effort to fill in