Phased-Array Laser Power Beaming from Cislunar Space to the Lunar Surface

We present a time-dependent, end-to-end framework for laser power beaming from cislunar orbits to the lunar surface. The model links on-orbit generation (solar arrays and wall-plug to optical), terrain-masked visibility and range, beam propagation with realistic divergence and jitter, and surface conversion with thermal and dust limits, returning delivered daily energy. Baseline loads for early polar activities (habitat survival, mobility, comm/nav, pilot ISRU) set target W h/day and are used consistently in scaling laws and design maps. A near-rectilinear halo orbit (NRHO) to a Shackleton-rim site provides a worked example: for a 2 m-class phased array at 1064 nm the reference geometry yields ~0.6-0.8 kW h/day to a 1m$^2$ receiver (about 28 W averaged over the day). We place this result in context by comparing on the same daily-energy metric to surface photovoltaics (PV) with storage and to compact fission, and by showing how delivered energy scales nearly linearly with transmit power and as $D_{\rm eff}^2$ via encircled-energy capture, with a multiplicative gain from visibility (constellations). The same framework indicates practical regimes already within reach: e.g., a 10 m effective-aperture optical phased array at $P_{\rm tx}=100$ kW delivers ~30-50 kW h/day at polar sites with typical single-orbiter visibility, as quantified by the delivered-energy and sizing maps. Thus, laser beaming is mass-competitive where darkness or permanent shadow forces deep storage for PV, or where distributed and duty-cycled users can amortize a shared transmitter; compact fission retains advantage for continuous multi-kW baseload at fixed sites.