Candidate mechanisms and fabric layup materials for the Mars surface tunnel concept

The Mars Surface Tunnel (MST) concept presented herein potentially addresses the three interconnected problems of planetary protection, minimizing Mars Ascent Vehicle (MAV) ascent mass, and keeping surface systems free of Martian dust in a manned Mars mission. If the crew can enter the MAV wearing Intra-Vehicular Activity (IVA) suits which are considerably lighter than the Extra-Vehicular Activity (EVA) suits, the MAV ascent mass can be significantly reduced. Furthermore, for long term operations on the Martian surface, there will always be a need to conveniently and habitably connect various surface elements such as habitats, rovers and science labs to one another. The proposed MST concept is a habitable, inflatable-deployable enclosure that connects surface elements while addressing the primary prerequisites mentioned above. We propose, four candidate mechanisms for the deployment, operation and retraction of the tunnel: a rail-guided tunnel, an air bridge type tunnel, and two variants of a spring-based tunnel. All the mechanisms have an inflatable tunnel which is initially deflated and stowed, pressurized just before use, and if required, subsequently deflated and stowed for future use. Metrics for comparison are used to rank the candidate mechanisms, and to select appropriate concepts for MAV-to-rover and habitat-to-habitat connection. A candidate fabric layup for the inflatable tunnel concept is proposed along with preliminary mass estimates based on prior experience in building inflatable space structures. The mass of the proposed tunnel concept connecting the MAV and the rover is estimated to be 219 kg. This lightweight, reusable system offers substantial benefits as a surface system in future human exploration, not only of Mars but also the Moon.