Tunnel Ready Elements for Active Deployment (T.R.E.A.D): NASA M2M X-HAB 2026 Challenge Final Report

The Baldwin Wallace University Engineering Department submitted a project proposal to NASA’s
Moon to Mars Exploration and Habitation Academic Innovation Challenge (M2M X-HAB). The
project goal was for engineering students to design and develop a reusable, deployable tunnel
system to facilitate travel between habitats on the Lunar and Martian surfaces. The importance
of re-usability is key to preventing the accumulation of buildings and tunnels that no longer serve
NASA’s purpose and accumulate on the surface. The challenge of these tunnels is to extend and
contract fully while also bending and moving along a nonlinear path to dock with other habitats
or surface assets. The end of the tunnel must also be able to actuate in six independent degrees of
freedom for successful docking. This is due to the high likelihood that the tunnel and habitat will
not be perfectly aligned following initial gross tunnel movement; thus, fine control is needed. Our
proposed solution to this problem is to combine tendon-based actuation with pressurized bladders
for rigidity. The central backbone of the proposed system will serve as the habitable walkway of
the tunnel. Therefore, the resistive forces needed to oppose the tendons and cause extension will
utilize the bladders embedded into the ribbing/supports of the tunnel. To achieve the necessary
bending and movement, a double tendon system is required. The first set of tendons controls the
initial half of the tunnel’s curvature, while the second controls the final half. Each set consists
of four individual cables controlled via a winch system. These tendon systems will also serve as
a primary means for retraction. The outer shell of the tunnel is inspired by previous inflatable
space projects, but adapts the layers to meet new environmental conditions, updated materials, and
preferred mechanical properties. The BW TREAD team evaluated the proposed solution through
a small-scale prototype, which was presented to the public during the annual “Ovation” student
project day at Baldwin Wallace University.