From early concepts to lunar hypertelescopes: roadmap for next-generation optical astronomy on the Moon

We present a historical and technical roadmap tracing the evolution of concepts that lead toward future lunar hypertelescopes for ultra-high-resolution optical astronomy. Building on diluted-aperture and interferometric concepts, we exploit recent progress in formation flying, precision metrology and lunar surface operations. The Moon offers unique advantages: seismically quiet ground, no atmosphere, cold traps for cryogenics, and long-term infrastructure potential. These enable sparse to kilometric baseline arrays far beyond Earth-based limits. We review paths from near-term precursor interferometers (10–100 m class) to large hypertelescope networks achieving milli- to micro-arcsecond resolution for direct imaging of exoplanets, stellar surfaces, and compact objects. Key milestones, scientific drivers, and engineering challenges are identified to evolve from current studies toward permanent lunar optical interferometric facilities.