Overview
This paper lays out a sequencing framework for lunar surface construction: what has to happen before a crew can occupy a habitat, and in what order, given the constraints of regolith, vacuum, thermal cycling, and limited launch mass.
Why sequencing is the hard problem
Most public discussion of lunar construction focuses on individual technologies. Regolith sintering, inflatable structures, 3D-printed shielding. Less attention goes to the order these steps have to happen in, and what has to be true on-site before each step is possible. A sintered regolith shell is only useful once you have power, and stable power is only useful once you have a landing zone clear of dust contamination risk. Sequencing, not any single technology, is what determines whether a habitat plan is actually buildable with the mass and crew time available.
A four-phase framework
We propose grouping lunar construction into four phases, each with its own success criteria before the next can begin:
Site preparation
Grading, dust mitigation, and landing pad hardening, done robotically ahead of crew arrival.
Utility deployment
Power, thermal management, and communications, sequenced so each later phase has what it needs before crew depend on it.
Shell construction
The pressure and radiation boundary, whether inflatable, printed, or buried, built to a standard that doesn't depend on perfect follow-on steps.
Habitation fit-out
The interior systems that turn a sealed shell into a place a crew can actually live and work in for months at a time.
Where most plans break down
In reviewing publicly available lunar base concepts, the most common failure point isn't a missing technology. It's an implicit assumption that a later phase's resources will already be available when an earlier phase needs them. Power budgets in particular tend to be sized for steady-state habitation, not for the construction phase itself, which is often more power-hungry and less forgiving of downtime.
What this means for near-term planning
A sequencing-first approach changes what gets prioritized in the next decade of lunar hardware development. Robotic site prep and utility deployment capable of running unattended for months, ahead of any crewed mission, matters more than headline shell-construction technology that has nowhere to attach until the earlier phases are solved.
Acknowledgments
Thanks to Niki Werkheiser, Grant Anderson, and Sam Scimemi for the conversations that shaped the thinking in this paper. Their combined experience across NASA technology maturation, life support systems, and ISS program leadership sharpened the sequencing framework considerably. Any remaining gaps are ours alone.