Selenograph: A Deterministic, Integrated Instrument for Cislunar Mission Analysis - Orbital Regime, Station-Keeping, Transfer, Carrying Capacity, and Formation

Selenograph is a deterministic instrument for cislunar (Earth–Moon) mission analysis. It answers the four core questions of cislunar mission design — will an orbit hold and what does it cost to keep; what is the cheapest transfer between orbits and when is its window; how many spacecraft can a region hold without collisions; and how is a formation coordinated so its members never drift into one another — from a single integrated engine, returning an answer in seconds where conventional, case-by-case analysis can take hours to weeks. The paper demonstrates each answer on the canonical Earth–Moon restricted three-body problem (mass ratio 0.01215), using a representative mission: a logistics depot with a relay formation in a Distant Retrograde Orbit (DRO) around the Moon. The depot orbit is verified periodic and classified "marginal" — the lunar-economy regime: not chaotic, not perfectly stable, but nearly self-holding, needing a station-keeping correction only about every 150 days, roughly five times cheaper than the L1/L2 gateway passes (about every 30 days). The low-energy transfer corridors that thread those gateways open below a precise Jacobi-energy threshold. The region shows a hard carrying-capacity ceiling: the fraction of collision-free arrangements falls from nearly 100% to exactly zero as the region fills — a structural, combinatorial limit set by the orbital mechanics, not a probabilistic decline. A relay formation is held collision-free for 29 m/s of fuel over 260 days by exploiting the predictable "beat" of the relative motion, which makes the contact and maneuver windows schedulable. The scope is stated plainly. The underlying observables are the classical restricted three-body problem; Selenograph's contribution is their integration into one fast, deterministic, auditable assessment, achieved by a proprietary integer-exact computational engine that is not disclosed in the paper. The carrying-capacity ceiling is reported as a structural property; the absolute spacecraft count for a specific region is a calibration deliverable. Results are demonstrated on a canonical configuration, not a population study. Selenograph is offered as an integrated, auditable complement to existing trajectory-design and space-domain-awareness tools. This preprint places the integrated instrument and its observables in the public domain as prior art; the proprietary computational engine is reserved. Selenograph is the third Lattice OS space instrument, alongside Kessler (orbital-debris collision risk) and Heliograph (solar-flare hazard).