We have studied the feasibility and scientific potential of zenithobserving liquid-mirror telescopes having 20-100 m diameters located onthe Moon. They would carry out deep infrared surveys to study thedistant universe and follow up discoveries made with the 6 m James WebbSpace Telescope (JWST), with more detailed images and spectroscopicstudies. They could detect objects 100 times fainter than JWST,observing the first high-redshift stars in the early universe and theirassembly into galaxies. We explored the scientific opportunities, keytechnologies, and optimum location of such telescopes. We havedemonstrated critical technologies. For example, the primary mirrorwould necessitate a high-reflectivity liquid that does not evaporate inthe lunar vacuum and remains liquid at less than 100 K. We have made acrucial demonstration by successfully coating an ionic liquid that hasnegligible vapor pressure. We also successfully experimented with aliquid mirror spinning on a superconducting bearing, as will be neededfor the cryogenic, vacuum environment of the telescope. We haveinvestigated issues related to lunar locations, concluding thatlocations within a few kilometers of a pole are ideal for deep sky coverand long integration times. We have located ridges and crater rimswithin 0.5° of the north pole that are illuminated for at least somesun angles during lunar winter, providing power and temperature control.We also have identified potential problems, like lunar dust. Issuesraised by our preliminary study demand additional in-depth analyses.These issues must be fully examined as part of a scientific debate thatwe hope to start with the present article.